Publications by year
2022
Zhu J, Chen X, Liu J, Jiang Y, Chen F, Lu J, Chen H, Zhai B, Reynolds DR, Chapman JW, et al (2022). A cold high-pressure system over North China hinders the southward migration of Mythimna separata in autumn.
Mov Ecol,
10(1).
Abstract:
A cold high-pressure system over North China hinders the southward migration of Mythimna separata in autumn.
BACKGROUND: in warm regions or seasons of the year, the planetary boundary layer is occupied by a huge variety and quantity of insects, but the southward migration of insects (in East Asia) in autumn is still poorly understood. METHODS: We collated daily catches of the oriental armyworm (Mythimna separata) moth from 20 searchlight traps from 2014 to 2017 in China. In order to explore the autumn migratory connectivity of M. separata in East China, we analyzed the autumn climate and simulated the autumn migration process of moths. RESULTS: the results confirmed that northward moth migration in spring and summer under the East Asian monsoon system can bring rapid population growth. However, slow southerly wind (blowing towards the north) prevailed over the major summer breeding area in North China (33°-40° N) due to a cold high-pressure system located there, and this severely disrupts the autumn 'return' migration of this pest. Less than 8% of moths from the summer breeding area successfully migrated back to their winter-breeding region, resulting in a sharp decline of the population abundance in autumn. As northerly winds (blowing towards the south) predominate at the eastern periphery of a high-pressure system, the westward movement of the high-pressure system leads to more northerlies over North China, increasing the numbers of moths migrating southward successfully. Therefore, an outbreak year of M. separata larvae was associated with a more westward position of the high-pressure system during the previous autumn. CONCLUSION: These results indicate that the southward migration in autumn is crucial for sustaining pest populations of M. separata, and the position of the cold high-pressure system in September is a key environmental driver of the population size in the next year. This study indicates that the autumn migration of insects in East China is more complex than previously recognized, and that the meteorological conditions in autumn are an important driver of migratory insects' seasonal and interannual population dynamics.
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Author URL.
Yaro AS, Linton Y-M, Dao A, Diallo M, Sanogo ZL, Samake D, Ousmane Y, Kouam C, Krajacich BJ, Faiman R, et al (2022). Diversity, composition, altitude, and seasonality of high-altitude windborne migrating mosquitoes in the Sahel: Implications for disease transmission. Frontiers in Epidemiology, 2
Yaro A, Linton Y-M, Dao A, Diallo M, Sanogo Z, Samake D, Ousman Y, Kouam C, Krajacich B, Faiman R, et al (2022). Diversity, composition, altitude, and seasonality of high-altitude windborne migrating mosquitoes in the Sahel: Implications for disease transmission.
Chen H, Wang Y, Huang L, Xu CF, Li JH, Wang FY, Cheng W, Gao BY, Chapman JW, Hu G, et al (2022). Flight Capability and the Low Temperature Threshold of a Chinese Field Population of the Fall Armyworm Spodoptera frugiperda.
Insects,
13(5).
Abstract:
Flight Capability and the Low Temperature Threshold of a Chinese Field Population of the Fall Armyworm Spodoptera frugiperda
The fall armyworm, Spodoptera frugiperda (J. E. Smith), is capable of long-distance migration; thus, evaluation of its flight capability is relevant to the design of monitoring and control strategies for this pest. Previous studies have quantified the flight ability of lab-reared populations under controlled conditions, but less is known about the flight capability of natural populations. In addition, the low temperature threshold for flight in natural populations also needs to be determined. In this study, the flight capability of S. frugiperda adults emerging from field-collected larvae in South China was measured by a flight mill system. The results show that the flight capability of S. frugiperda moths varied greatly between individuals, and that some adults are capable of flying great distances. The longest self-powered flight distance was 116.7 km with a cumulative flight duration of 36.51 h during a 48-h period. Typically, the flight activity of tethered individuals was relatively stable during the first 12 h, indicating that migrating moths can fly through an entire night. Based on the accumulated flight duration in the first 12 h, moths can be clearly divided into two groups (
Abstract.
Doyle T, Jimenez-Guri E, Hawkes WLS, Massy R, Mantica F, Permanyer J, Cozzuto L, Hermoso Pulido T, Baril T, Hayward A, et al (2022). Genome-wide transcriptomic changes reveal the genetic pathways involved in insect migration.
Mol Ecol,
31(16), 4332-4350.
Abstract:
Genome-wide transcriptomic changes reveal the genetic pathways involved in insect migration.
Insects are capable of extraordinary feats of long-distance movement that have profound impacts on the function of terrestrial ecosystems. The ability to undertake these movements arose multiple times through the evolution of a suite of traits that make up the migratory syndrome, however the underlying genetic pathways involved remain poorly understood. Migratory hoverflies (Diptera: Syrphidae) are an emerging model group for studies of migration. They undertake seasonal movements in huge numbers across large parts of the globe and are important pollinators, biological control agents and decomposers. Here, we assembled a high-quality draft genome of the marmalade hoverfly (Episyrphus balteatus). We leveraged this genomic resource to undertake a genome-wide transcriptomic comparison of actively migrating Episyrphus, captured from a high mountain pass as they flew south to overwinter, with the transcriptomes of summer forms which were non-migratory. We identified 1543 genes with very strong evidence for differential expression. Interrogation of this gene set reveals a remarkable range of roles in metabolism, muscle structure and function, hormonal regulation, immunity, stress resistance, flight and feeding behaviour, longevity, reproductive diapause and sensory perception. These features of the migrant phenotype have arisen by the integration and modification of pathways such as insulin signalling for diapause and longevity, JAK/SAT for immunity, and those leading to octopamine production and fuelling to boost flight capabilities. Our results provide a powerful genomic resource for future research, and paint a comprehensive picture of global expression changes in an actively migrating insect, identifying key genomic components involved in this important life-history strategy.
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Hawkes WLS, Walliker E, Gao B, Forster O, Lacey K, Doyle T, Massy R, Roberts NW, Reynolds DR, Özden Ö, et al (2022). Huge spring migrations of insects from the Middle East to Europe: quantifying the migratory assemblage and ecosystem services.
Ecography,
2022(10).
Abstract:
Huge spring migrations of insects from the Middle East to Europe: quantifying the migratory assemblage and ecosystem services
Migratory insects are a key component of terrestrial ecosystems, but understanding their full contribution is challenging as they are difficult to track, and migration often takes place at high altitude. Migration hotspots offer an exceptional opportunity to study these otherwise indiscernible movements as migration can be visible at ground level; however these events are often also ephemeral and reported only from chance encounters. It is therefore often difficult to fully characterise the range and number of species involved, the drivers of migration or to appreciate the potential interactions and ecological roles of the migrants. Here we pursue field evidence suggesting that the Karpaz peninsula in northeast Cyprus is a suitable location to systematically collect data on migratory insects. In the spring of 2019, using a combination of timed‐counts, migration‐camera traps and netting we documented over 39 million day‐flying insects from eight orders arriving on Cyprus at rates of up to 5900 insects m‐1 min‐1. Mass arrivals were correlated with higher temperatures and easterly winds. Wind direction and normalised vegetation difference index (NDVI) data suggest that these insects had their natal origins in locations including Syria, Iraq and Saudi Arabia. It is estimated that many billions of insects left the coast of the Middle East heading west into Europe during the study period. While the migrant assemblage was diverse, Diptera were by far the most numerous insect order (86%) followed by Lepidoptera (10%). These migrating insects play a range of vital ecological roles including cross‐continental pollination and the transfer of important nutrients. We believe that the very infrequently explored processes described in this manuscript have important consequences for ecosystems in the destinations of these migratory insects across Europe.
Abstract.
Menz MHM, Scacco M, Bürki-Spycher H-M, Williams HJ, Reynolds DR, Chapman JW, Wikelski M (2022). Individual tracking reveals long-distance flight-path control in a nocturnally migrating moth.
Science,
377(6607), 764-768.
Abstract:
Individual tracking reveals long-distance flight-path control in a nocturnally migrating moth
Each year, trillions of insects make long-range seasonal migrations. These movements are relatively well understood at a population level, but how individual insects achieve them remains elusive. Behavioral responses to conditions en route are little studied, primarily owing to the challenges of tracking individual insects. Using a light aircraft and individual radio tracking, we show that nocturnally migrating death’s-head hawkmoths maintain control of their flight trajectories over long distances. The moths did not just fly with favorable tailwinds; during a given night, they also adjusted for head and crosswinds to precisely hold course. This behavior indicates that the moths use a sophisticated internal compass to maintain seasonally beneficial migratory trajectories independent of wind conditions, illuminating how insects traverse long distances to take advantage of seasonal resources.
Abstract.
Guo JW, Cui Y, Lin PJ, Zhai BP, Lu ZX, Chapman JW, Hu G (2022). Male nutritional status does not impact the reproductive potential of female Cnaphalocrocis medinalis moths under conditions of nutrient shortage.
Insect Science,
29(2), 467-477.
Abstract:
Male nutritional status does not impact the reproductive potential of female Cnaphalocrocis medinalis moths under conditions of nutrient shortage
In addition to sperm, some accessory substances transferred to females during copulation act as nuptial gifts by passing on valuable nutrients in many insect species. The nutritional status of the males can thus have a great effect on the mating behavior, fecundity and even the longevity of females. However, little is known about the effect of male nutritional status on the female reproductive traits in migratory insect species, particularly when females experience nutrient shortage and have to choose between reproduction and migration. Here, Cnaphalocrocis medinalis, a migratory rice pest in Asia, was studied to explore this issue. Our results showed that in male moths fed with honey solution, their gonads had higher energy content than gonads of starved males, resulting in increased energy content of the bursa copulatrix of females after mating with fed males. Such females showed increased mating frequency, fecundity and longevity compared to females mating with starved males, indicating that male moths deliver nuptial gifts to females and improve their reproductive performance. However, when females were starved, only about 45% mated, with just a single copulation, regardless of male nutritional status. Starved females showed lower fecundity, and a longer pre-oviposition period (indicating a greater propensity to migrate), compared to fed females. However, copulation still significantly extended their longevity. These results suggest that starved females invest in migration to escape deteriorating habitats, rather than investing the nuptial gift to increased fecundity. Our results further our understanding of the reproductive adaptability of migratory insects under conditions of food stress.
Abstract.
Shamoun-Baranes J, Bauer S, Chapman JW, Desmet P, Dokter AM, Farnsworth A, van Gasteren H, Haest B, Koistinen J, Kranstauber B, et al (2022). Meteorological Data Policies Needed to Support Biodiversity Monitoring with Weather Radar. Bulletin of the American Meteorological Society, 103(4), e1234-e1242.
Shi X, Hu C, Soderholm J, Chapman J, Mao H, Cui K, Ma Z, Wu D, Fuller RA (2022). Prospects for monitoring bird migration along the East <scp>Asian‐Australasian</scp> Flyway using weather radar.
Remote Sensing in Ecology and Conservation,
9(2), 169-181.
Abstract:
Prospects for monitoring bird migration along the East Asian‐Australasian Flyway using weather radar
AbstractEach year, billions of birds migrate across the globe, and interpretation of weather radar signals is increasingly being used to document the spatial and temporal migration patterns in Europe and America. Such approaches are yet to be applied in the East Asian‐Australasian Flyway (EAAF), one of the most species‐rich and threatened flyways in the world. Logistical challenges limit direct on‐ground monitoring of migratory birds in many parts of the EAAF, resulting in knowledge gaps on population status and site use that limit evidence‐based conservation planning. Weather radar data have great potential for achieving comprehensive migratory bird monitoring along the EAAF. In this study, we discuss the feasibility and challenges of using weather radar to complement on‐ground bird migration surveys in the flyway. We summarize the location, capacity and data availability of weather radars across EAAF countries, as well as the spatial coverage of the radars with respect to migrants' geographic distribution and migration hotspots along the flyway, with an exemplar analysis of biological movement patterns extracted from Chinese weather radars. There are more than 430 weather radars in EAAF countries, covering on average half of bird species' passage and non‐breeding distributions, as well as 70% of internationally important sites for migratory shorebirds. We conclude that the weather radar network could be a powerful resource for monitoring bird movements over the full annual cycle throughout much of the EAAF, providing estimates of migration traffic rates, site use, and long‐term population trends, especially in remote and less‐surveyed regions. Analyses of weather radar data would complement existing ornithological surveys and help understand the past and present status of the avian community in a highly threatened flyway.
Abstract.
Chowdhury S, Cardillo M, Chapman J, Green D, Norris R, Riva F, Zalucki M, Fuller R (2022). Protected areas fail to cover the full annual cycle of migratory butterflies.
Abstract:
Protected areas fail to cover the full annual cycle of migratory butterflies
Abstract
. Effective conservation of migratory species relies on protection throughout their annual cycle1, something that has not been assessed globally for migratory insects. Here, we develop seasonal ecological niche models for 405 migratory butterfly species globally to assess whether they are adequately covered by protected areas (PAs) across their full annual cycle. PA coverage was inadequate in at least one season for 83% of migratory butterflies and 17% only achieved target representation in one season, and 43% did not meet the target representation in any season. While 95% of migratory butterflies met the target representation in Australia, only 1% did so in the Oriental region, indicating marked geographic variation in PA coverage. Coordinated efforts, across multiple countries, are needed to develop PAs that conserve migratory animals.
Abstract.
Stefanescu C, Hu G, Oliver TH, Reynolds DR, Chapman JW (2022). Reply to López-Mañas et al.: Spatial population models of migrants should be underpinned by phenology, behavior, and ecology.
Proc Natl Acad Sci U S A,
119(19).
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Lukach M, Dally T, Evans W, Hassall C, Duncan EJ, Bennett L, Addison FI, Kunin WE, Chapman JW, Neely RRIII, et al (2022). The development of an unsupervised hierarchical clustering analysis of dual-polarization weather surveillance radar observations to assess nocturnal insect abundance and diversity.
REMOTE SENSING IN ECOLOGY AND CONSERVATION,
8(5), 698-716.
Author URL.
2021
Hu G, Stefanescu C, Oliver TH, Roy DB, Brereton T, Van Swaay C, Reynolds DR, Chapman JW (2021). Environmental drivers of annual population fluctuations in a trans-Saharan insect migrant.
Proceedings of the National Academy of Sciences,
118(26).
Abstract:
Environmental drivers of annual population fluctuations in a trans-Saharan insect migrant
SignificanceThe painted lady butterfly is an annual migrant to northern regions, but the size of the immigration varies by more than 100-fold in successive years. Unlike the monarch, the painted lady breeds year round, and it has long been suspected that plant-growing conditions in winter-breeding locations drive this high annual variability. However, the regions where caterpillars develop over winter remained unclear. Here, we show for the European summer population that winter plant greenness in the savanna of sub-Saharan Africa is the key driver of the size of the spring immigration. Our results show that painted ladies regularly cross the Sahara Desert and elucidate the climatic drivers of the annual population dynamics.
Abstract.
Jyothi P, Aralimarad P, Wali V, Dave S, Bheemanna M, Ashoka J, Shivayogiyappa P, Lim KS, Chapman JW, Sane SP, et al (2021). Evidence for facultative migratory flight behavior in Helicoverpa armigera (Noctuidae: Lepidoptera) in India.
PLoS ONE,
16(1 January).
Abstract:
Evidence for facultative migratory flight behavior in Helicoverpa armigera (Noctuidae: Lepidoptera) in India
Despite its deleterious impact on farming and agriculture, the physiology and energetics of insect migration is poorly understood due to our inability to track their individual movements in the field. Many insects, e.g. monarch butterflies, Danaus plexippus (L.), are facultative migrants. Hence, it is important to establish whether specific insect populations in particular areas migrate. The polyphagous insect, Helicoverpa armigera (Hübner), is especially interesting in this regard due to its impact on a variety of crops. Here, we used a laboratorybased flight mill assay to show that Helicoverpa armigera populations clearly demonstrate facultative migration in South India. Based on various flight parameters, we categorized male and female moths as long, medium or short distance fliers. A significant proportion of moths exhibited long-distance flight behavior covering more than 10 km in a single night, averaging about 8 flight hours constituting 61% flight time in the test period. The maximum and average flight speeds of these long fliers were greater than in the other categories. Flight activity across sexes also varied; male moths exhibited better performance than female moths. Wing morphometric parameters including forewing length, wing loading, and wing aspect ratio were key in influencing long-distance flight. Whereas forewing length positively correlated with flight distance and duration, wing loading was negatively correlated.
Abstract.
Massy R, Hawkes WLS, Doyle T, Troscianko J, Menz MHM, Roberts NW, Chapman JW, Wotton KR (2021). Hoverflies use a time-compensated sun compass to orientate during autumn migration.
Proceedings of the Royal Society B: Biological Sciences,
288(1959), 20211805-20211805.
Abstract:
Hoverflies use a time-compensated sun compass to orientate during autumn migration
The sun is the most reliable celestial cue for orientation available to daytime migrants. It is widely assumed that diurnal migratory insects use a ‘time-compensated sun compass’ to adjust for the changing position of the sun throughout the day, as demonstrated in some butterfly species. The mechanisms used by other groups of diurnal insect migrants remain to be elucidated. Migratory species of hoverflies (Diptera: Syrphidae) are one of the most abundant and beneficial groups of diurnal migrants, providing multiple ecosystem services and undergoing directed seasonal movements throughout much of the temperate zone. To identify the hoverfly navigational strategy, a flight simulator was used to measure orientation responses of the hoverfliesScaeva pyrastriandScaeva seleniticato celestial cues during their autumn migration. Hoverflies oriented southwards when they could see the sun and shifted this orientation westward following a 6 h advance of their circadian clocks. Our results demonstrate the use of a time-compensated sun compass as the primary navigational mechanism, consistent with field observations that hoverfly migration occurs predominately under clear and sunny conditions.
Abstract.
Chowdhury S, Fuller RA, Dingle H, Chapman JW, Zalucki MP (2021). Migration in butterflies: a global overview.
Biol Rev Camb Philos Soc,
96(4), 1462-1483.
Abstract:
Migration in butterflies: a global overview.
Insect populations including butterflies are declining worldwide, and they are becoming an urgent conservation priority in many regions. Understanding which butterfly species migrate is critical to planning for their conservation, because management actions for migrants need to be coordinated across time and space. Yet, while migration appears to be widespread among butterflies, its prevalence, as well as its taxonomic and geographic distribution are poorly understood. The study of insect migration is hampered by their small size and the difficulty of tracking individuals over long distances. Here we review the literature on migration in butterflies, one of the best-known insect groups. We find that nearly 600 butterfly species show evidence of migratory movements. Indeed, the rate of 'discovery' of migratory movements in butterflies suggests that many more species might in fact be migratory. Butterfly migration occurs across all families, in tropical as well as temperate taxa; Nymphalidae has more migratory species than any other family (275 species), and Pieridae has the highest proportion of migrants (13%; 133 species). Some 13 lines of evidence have been used to ascribe migration status in the literature, but only a single line of evidence is available for 92% of the migratory species identified, with four or more lines of evidence available for only 10 species - all from the Pieridae and Nymphalidae. Migratory butterflies occur worldwide, although the geographic distribution of migration in butterflies is poorly resolved, with most data so far coming from Europe, USA, and Australia. Migration is much more widespread in butterflies than previously realised - extending far beyond the well-known examples of the monarch Danaus plexippus and the painted lady Vanessa cardui - and actions to conserve butterflies and insects in general must account for the spatial dependencies introduced by migratory movements.
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Hedlund JSU, Lv H, Lehmann P, Hu G, Anderson RC, Chapman JW (2021). Unraveling the World's Longest Non-stop Migration: the Indian Ocean Crossing of the Globe Skimmer Dragonfly.
FRONTIERS IN ECOLOGY AND EVOLUTION,
9 Author URL.
Shamoun-Baranes J, Bauer S, Chapman JW, Desmet P, Dokter AM, Farnsworth A, Haest B, Koistinen J, Kranstauber B, Liechti F, et al (2021). Weather radars' role in biodiversity monitoring. Science, 372(6539).
2020
Gao B, Wotton KR, Hawkes WLS, Menz MHM, Reynolds DR, Zhai B-P, Hu G, Chapman JW (2020). Adaptive strategies of high-flying migratory hoverflies in response to wind currents.
Proceedings of the Royal Society B: Biological Sciences,
287(1928), 20200406-20200406.
Abstract:
Adaptive strategies of high-flying migratory hoverflies in response to wind currents
Large migrating insects, flying at high altitude, often exhibit complex behaviour. They frequently elect to fly on winds with directions quite different from the prevailing direction, and they show a degree of common orientation, both of which facilitate transport in seasonally beneficial directions. Much less is known about the migration behaviour of smaller (10–70 mg) insects. To address this issue, we used radar to examine the high-altitude flight of hoverflies (Diptera: Syrphidae), a group of day-active, medium-sized insects commonly migrating over the UK. We found that autumn migrants, which must move south, did indeed show migration timings and orientation responses that would take them in this direction, despite the unfavourability of the prevailing winds. Evidently, these hoverfly migrants must have a compass (probably a time-compensated solar mechanism), and a means of sensing the wind direction (which may be determined with sufficient accuracy at ground level, before take-off). By contrast, hoverflies arriving in the UK in spring showed weaker orientation tendencies, and did not correct for wind drift away from their seasonally adaptive direction (northwards). However, the spring migrants necessarily come from the south (on warm southerly winds), so we surmise that complex orientation behaviour may not be so crucial for the spring movements.
Abstract.
Florio J, Verú LM, Dao A, Yaro AS, Diallo M, Sanogo ZL, Samaké D, Huestis DL, Yossi O, Talamas E, et al (2020). Diversity, dynamics, direction, and magnitude of high-altitude migrating insects in the Sahel.
Sci Rep,
10(1).
Abstract:
Diversity, dynamics, direction, and magnitude of high-altitude migrating insects in the Sahel.
Long-distance migration of insects impacts food security, public health, and conservation-issues that are especially significant in Africa. Windborne migration is a key strategy enabling exploitation of ephemeral havens such as the Sahel, however, its knowledge remains sparse. In this first cross-season investigation (3 years) of the aerial fauna over Africa, we sampled insects flying 40-290 m above ground in Mali, using nets mounted on tethered helium-filled balloons. Nearly half a million insects were caught, representing at least 100 families from thirteen orders. Control nets confirmed that the insects were captured at altitude. Thirteen ecologically and phylogenetically diverse species were studied in detail. Migration of all species peaked during the wet season every year across localities, suggesting regular migrations. Species differed in flight altitude, seasonality, and associated weather conditions. All taxa exhibited frequent flights on southerly winds, accounting for the recolonization of the Sahel from southern source populations. "Return" southward movement occurred in most taxa. Estimates of the seasonal number of migrants per species crossing Mali at latitude 14°N were in the trillions, and the nightly distances traversed reached hundreds of kilometers. The magnitude and diversity of windborne insect migration highlight its importance and impacts on Sahelian and neighboring ecosystems.
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Author URL.
Zhang L, Cheng L, Chapman JW, Sappington TW, Liu J, Cheng Y, Jiang X (2020). Juvenile hormone regulates the shift from migrants to residents in adult oriental armyworm, Mythimna separata.
Sci Rep,
10(1).
Abstract:
Juvenile hormone regulates the shift from migrants to residents in adult oriental armyworm, Mythimna separata.
In migratory insects, increasing evidence has demonstrated juvenile hormone (JH) is involved in regulating adult reproduction and flight. Our previous study demonstrated that the switch from migrants to residents in Mythimna separata could be induced by adverse environmental conditions during a sensitive period in adulthood (the first day post-emergence), but the role of JH in this switch is not clear. Here, we found a significantly different pattern of JH titers between migrants and residents, with migrants showing a slower release of JH during adulthood than residents. Application of JH analogue (JHA) in the 1-day-old adults, significantly accelerated adult reproduction and suppressed flight capacity. The pre-oviposition period and period of first oviposition of migrants treated with JHA were significantly shorter, while the total lifetime fecundity and mating percentage increased. The flight capacity and dorso-longitudinal muscle size of the migrants were decreased significantly when treated with JHA. The effect of JHA on reproduction and flight capacity indicate that JH titers during the sensitive period (first day post-emergence) regulates the shift from migrants to residents in M. separata.
Abstract.
Author URL.
Florio J, Verú L, Dao A, Yaro A, Diallo M, Sanogo Z, Samaké D, Huestis D, Yossi O, Talamas E, et al (2020). Massive windborne migration of Sahelian insects: Diversity, seasonality, altitude, and direction.
Wang Y-P, Tu X-B, Lin P-J, Li S, Xu C-M, Wang X-Q, Reynolds DR, Chapman J, Zhang Z-H, Hu G, et al (2020). Migratory Take-Off Behaviour of the Mongolian Grasshopper Oedaleus asiaticus.
Insects,
11(7).
Abstract:
Migratory Take-Off Behaviour of the Mongolian Grasshopper Oedaleus asiaticus.
Oedaleus asiaticus is one of the dominant species of grasshoppers in the rangeland on the Mongolian plateau, and a serious pest, but its migratory behavior is poorly known. We investigated the take-off behavior of migratory O. asiaticus in field cages in the inner Mongolia region of northern China. The species shows a degree of density-dependent phase polyphenism, with high-density swarming populations characterized by a brown morph, while low-density populations are more likely to comprise a green morph. We found that only 12.4% of brown morphs engaged in migratory take-off, and 2.0% of green morphs. Migratory grasshoppers took off at dusk, especially in the half hour after sunset (20:00-20:30 h). Most emigrating individuals did not have any food in their digestive tract, and the females were mated but with immature ovaries. In contrast, non-emigrating individuals rarely had empty digestive tracts, and most females were mated and sexually mature. Therefore, it seems clear that individuals prepare for migration in the afternoon by eliminating food residue from the body, and migration is largely restricted to sexually immature stages (at least in females). Furthermore, it was found that weather conditions (particularly temperature and wind speed at 15:00 h) in the afternoon had a significant effect on take-off that evening, with O. asiaticus preferring to take off in warm, dry and calm weather. The findings of this study will contribute to a reliable basis for forecasting migratory movements of this pest.
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Author URL.
Wang Y-P, Wu M-F, Lin P-J, Wang Y, Chen A-D, Jiang Y-Y, Zhai B-P, Chapman JW, Hu G (2020). Plagues of Desert Locust: No invasion risk to China.
Abstract:
Plagues of Desert Locust: No invasion risk to China
AbstractRecently, the most serious upsurge of desert locust (Schistocerca gregaria) in the last 25 years is spreading across eastern Africa and southwestern Asia. Parts of the desert locust ‘invasion area’, namely the northern border areas of Pakistan and India are very close to China, and whether locust swarms will invade China is of wide concern. To answer this question, we identified areas of potentially suitable habitat for the desert locust within China based on historical precipitation and temperature data, and found that parts of Xinjiang and Inner Mongolia provinces could provide ephemeral habitat in summer, but these places are remote from any other desert locust breeding area. Presently, the desert locust populations in Pakistan and India are mature and have laid eggs, and are less likely to spread long distances. The next generation of adults will appear in April and May, and so we examined twenty years’ historical wind data (2000–2019) for this period. Our results showed that winds at the height of locust swarm flight blew eastward during April and May, but the wind speeds were quite slow and would not facilitate desert locust eastward migration over large distances. Furthermore, simulated trajectories of desert locust swarms with 10 days’ migration mostly ended within India. The most easterly point of these trajectories just reached eastern India, close to the border between India and Myanmar, and this is very close to the eastern border of the invasion area of desert locust described in previous studies. In conclusion, the risk that the desert locust will invade China is very low.
Abstract.
Wang Y-P, Wu M-F, Lin P-J, Wang Y, Chen A-D, Jiang Y-Y, Zhai B-P, Chapman JW, Hu G (2020). Plagues of Desert Locusts: Very Low Invasion Risk to China.
Insects,
11(9), 628-628.
Abstract:
Plagues of Desert Locusts: Very Low Invasion Risk to China
Recently, the most serious upsurge of the desert locust (Schistocerca gregaria) in the last 25 years is spreading across eastern Africa and southwestern Asia. Parts of the desert locust ‘invasion area’, namely the northern border areas of Pakistan and India, are very close to China, and whether locust swarms will invade China is of wide concern. To answer this question, we identified areas of potentially suitable habitat for the desert locust within China based on historical precipitation and temperature data, and found that parts of Xinjiang and Inner Mongolia provinces could provide ephemeral habitat in summer, but these places are remote from any other desert locust breeding areas. New generation adults of the desert locust in Pakistan and India present since April led to swarms spreading into the Indo-Pakistan border region in June, and so we examined historical wind data for this period. Our results showed that winds at the altitude of locust swarm flight blew eastward during April–June, but the wind speeds were quite slow and would not facilitate desert locust eastward migration over large distances. Simulated trajectories of desert locust swarms undertaking 10-day migrations mostly ended within India. The most easterly point of these trajectories just reached eastern India, and this is very close to the eastern border of the invasion area of desert locusts described in previous studies. Overall, the risk that the desert locust will invade China is very low.
Abstract.
Li X-J, Wu M-F, Ma J, Gao B-Y, Wu Q-L, Chen A-D, Liu J, Jiang Y-Y, Zhai B-P, Early R, et al (2020). Prediction of migratory routes of the invasive fall armyworm in eastern China using a trajectory analytical approach.
Pest Manag Sci,
76(2), 454-463.
Abstract:
Prediction of migratory routes of the invasive fall armyworm in eastern China using a trajectory analytical approach.
BACKGROUND: the fall armyworm (FAW), an invasive pest from the Americas, is rapidly spreading through the Old World, and has recently invaded the Indochinese Peninsula and southern China. In the Americas, FAW migrates from winter-breeding areas in the south into summer-breeding areas throughout North America where it is a major pest of corn. Asian populations are also likely to evolve migrations into the corn-producing regions of eastern China, where they will pose a serious threat to food security. RESULTS: to evaluate the invasion risk in eastern China, the rate of expansion and future migratory range was modelled by a trajectory simulation approach, combined with flight behavior and meteorological data. Our results predict that FAW will migrate from its new year-round breeding regions into the two main corn-producing regions of eastern China (Huang-Huai-Hai Summer Corn and Northeast Spring Corn Regions), via two pathways. The western pathway originates in Myanmar and Yunnan, and FAW will take four migration steps (i.e. four generations) to reach the Huang-Huai-Hai Region by July. Migration along the eastern pathway from Indochina and southern China progresses faster, with FAW reaching the Huang-Huai-Hai Region in three steps by June and reaching the Northeast Spring Region in July. CONCLUSION: Our results indicate that there is a high risk that FAW will invade the major corn-producing areas of eastern China via two migration pathways, and cause significant impacts to agricultural productivity. Information on migration pathways and timings can be used to inform integrated pest management strategies for this emerging pest. © 2019 Society of Chemical Industry.
Abstract.
Author URL.
Satterfield DA, Sillett TS, Chapman JW, Altizer S, Marra PP (2020). Seasonal insect migrations: massive, influential, and overlooked.
FRONTIERS IN ECOLOGY AND THE ENVIRONMENT,
18(6), 335-344.
Author URL.
Gao B, Hedlund J, Reynolds DR, Zhai B, Hu G, Chapman JW (2020). The ‘migratory connectivity’ concept, and its applicability to insect migrants.
Movement Ecology,
8(1).
Abstract:
The ‘migratory connectivity’ concept, and its applicability to insect migrants
AbstractMigratory connectivity describes the degree of linkage between different parts of an animal’s migratory range due to the movement trajectories of individuals. High connectivity occurs when individuals from one particular part of the migratory range move almost exclusively to another localized part of the migratory range with little mixing with individuals from other regions. Conversely, low migratory connectivity describes the situation where individuals spread over a wide area during migration and experience a large degree of mixing with individuals from elsewhere. The migratory connectivity concept is frequently applied to vertebrate migrants (especially birds), and it is highly relevant to conservation and management of populations. However, it is rarely employed in the insect migration literature, largely because much less is known about the migration circuits of most migratory insects than is known about birds. In this review, we discuss the applicability of the migratory connectivity concept to long-range insect migrations. In contrast to birds, insect migration circuits typically comprise multigenerational movements of geographically unstructured (non-discrete) populations between broad latitudinal zones. Also, compared to the faster-flying birds, the lower degree of control over movement directions would also tend to reduce connectivity in many insect migrants. Nonetheless, after taking account of these differences, we argue that the migratory connectivity framework can still be applied to insects, and we go on to consider postulated levels of connectivity in some of the most intensively studied insect migrants. We conclude that a greater understanding of insect migratory connectivity would be of value for conserving threatened species and managing pests.
Abstract.
2019
Denerley C, Redpath SM, van der Wal R, Newson SE, Chapman JW, Wilson JD (2019). Breeding ground correlates of the distribution and decline of the Common Cuckoo Cuculus canorus at two spatial scales.
Ibis,
161(2), 346-358.
Abstract:
Breeding ground correlates of the distribution and decline of the Common Cuckoo Cuculus canorus at two spatial scales
Many migratory bird species are undergoing population declines as a result of potentially multiple, interacting mechanisms. Understanding the environmental associations of spatial variation in population change can help tease out the likely mechanisms involved. Common Cuckoo Cuculus canorus populations have declined by 69% in England but increased by 33% in Scotland. The declines have mainly occurred in lowland agricultural landscapes, but their mechanisms are unknown. At both the local scale within the county of Devon (SE England) and at the national (UK) scale, we analysed the breeding season distribution of Cuckoos in relation to habitat variation, the abundance of host species and the abundance of moth species whose caterpillars are a key food of adult Cuckoos. At the local scale, we found that Cuckoos were more likely to be detected in areas with more semi-natural habitat, more Meadow Pipits Anthus pratensis (but fewer Dunnocks Prunella modularis) and where, later in the summer, higher numbers of moths were captured whose larvae are Cuckoo prey. Nationally, Cuckoos have become more associated with upland heath characterized by the presence of Meadow Pipit hosts, and with wetland habitats occupied by Eurasian Reed Warbler Acrocephalus scirpaceus hosts. The core distribution of Cuckoos has shifted from south to north within the UK. By the end of 2009, the abundance of macro-moth species identified as prey had also declined four times faster than that of species not known to be taken by Cuckoos. The abundance of these moths has shown the sharpest declines in grassland, arable and woodland habitats and has increased in semi-natural habitats (heaths and rough grassland). Our study suggests that Cuckoos are likely to remain a very scarce bird in lowland agricultural landscapes without large-scale changes in agricultural practices.
Abstract.
Chapman JW, Drake VA (2019). Insect migration. In (Ed)
Encyclopedia of Animal Behavior, 573-580.
Abstract:
Insect migration
Abstract.
Wotton KR, Boya G, Menz M, Morris R, Ball S, Lim K, Reynolds D, Hu G, Chapman J (2019). Mass Seasonal Migrations of Hoverflies Provide Extensive Pollination and Crop Protection Services. Current Biology, 29(13), 2167-2173.
Tu X, Hu G, Fu X, Zhang Y, Ma J, Wang Y, Gould PJL, Du G, Su H, Zhang Z, et al (2019). Mass windborne migrations extend the range of the migratory locust in East China.
Agricultural and Forest Entomology,
22(1), 41-49.
Abstract:
Mass windborne migrations extend the range of the migratory locust in East China
Abstract
Migratory insect pests pose a substantial challenge to global food security. These issues are particularly acute when pest incursions occur considerably beyond the expected range, through natural migration or human‐aided transport, because the lack of species‐specific control strategies and a potential absence of species‐specific natural enemies in the newly‐invaded area may lead to rapid establishment of a new pest.
One such threat is posed by the Oriental migratory locust Locusta migratoria manilensis in China, which, historically, has been restricted to eastern China from the Bohai Gulf southwards, and now threatens to expand its range into the agriculturally important region of northeast China.
We analyzed data from a recent outbreak of migratory locusts in Heilongjiang Province (extreme northeast China), > 700 km north of its current known range, and identified the source region, timing of arrival and probable migratory routes of this incursion.
We further show that warming temperatures in this region will likely allow subsequent invasions to establish permanent populations in northeast China, and thus authorities in this important crop‐producing region of East Asia should be vigilant to the threat posed by this species.
Abstract.
Menz MHM, Reynolds DR, Gao B, Hu G, Chapman JW, Wotton KR (2019). Mechanisms and Consequences of Partial Migration in Insects. Frontiers in Ecology and Evolution, 7
Wu Q, Hu G, Tuan HA, Chen X, Lu M, Zhai B, Chapman JW (2019). Migration patterns and winter population dynamics of rice planthoppers in Indochina: New perspectives from field surveys and atmospheric trajectories.
Agricultural and Forest Meteorology,
265, 99-109.
Abstract:
Migration patterns and winter population dynamics of rice planthoppers in Indochina: New perspectives from field surveys and atmospheric trajectories
Rice planthoppers (RPH) are the most serious insect pests of rice production in East Asia, frequently out-breaking in China, Korea and Japan each summer. They are unable to overwinter in temperate East Asia, and summer populations arise anew each year via northward spring migration from south-east Asia. The annual migration cycle is generally believed to be a closed loop with mass returns to south-east Asia in the autumn, but this leg of the journey and the overwintering dynamics are much less studied than the spring immigrations. Previous studies have indicated that the north-central Vietnam (NCV) region is a key location for both the spring colonisation of China and for receiving return migrants from southern China each autumn. However, NCV experiences a three-month rice-free fallow period during mid-winter, and so it cannot be the principal over-wintering region for RPH populations. In this study, the continental-scale migration patterns of RPH in East Asia were explored using data from light trap catches, field surveys and atmospheric trajectory simulations. Our results confirmed that large numbers of return migrants arrive in NCV from southern China each autumn, but that they are unable to survive there over winter. The NCV region is recolonised in the early-spring (mid-February to mid-March) of each year by migrants from winter rice-growing regions in north-east Thailand, southern Laos and south-central coastal Vietnam, which are transported on favourable high-altitude synoptic winds. The following generation initiates the colonisation of East Asia from a large source population in NCV. Our results provide a new perspective on RPH migration patterns and over-wintering dynamics in East Asia, which is governed by crop production, environmental conditions and synoptic wind patterns at a continental scale.
Abstract.
Jones CM, Parry H, Tay WT, Reynolds DR, Chapman JW (2019). Movement Ecology of Pest Helicoverpa: Implications for Ongoing Spread.
Annu Rev Entomol,
64, 277-295.
Abstract:
Movement Ecology of Pest Helicoverpa: Implications for Ongoing Spread.
The recent introduction and spread of Helicoverpa armigera throughout South America highlight the invasiveness and adaptability of moths in the Helicoverpa genus. Long-range movement in three key members, H. armigera, H. zea, and H. punctigera, occurs by migration and international trade. These movements facilitate high population admixture and genetic diversity, with important economic, biosecurity, and control implications in today's agricultural landscape. This is particularly true for the spread of resistance alleles to transgenic crops expressing Bacillus thuringiensis (Bt) toxins that are planted over vast areas to suppress Helicoverpa spp. The ability to track long-distance movement through radar technology, population genetic markers, and/or long-distance dispersal modeling has advanced in recent years, yet we still know relatively little about the population trajectories or migratory routes in Helicoverpa spp. Here, we consider how experimental and theoretical approaches can be integrated to fill key knowledge gaps and assist management practices.
Abstract.
Author URL.
Li X-J, Wu M-F, Ma J, Gao B-Y, Wu Q-L, Chen A-D, Liu J, Jiang Y-Y, Zhai B-P, Early R, et al (2019). Prediction of migratory routes of the invasive fall armyworm in eastern China using a trajectory analytical approach.
Schmid B, Zaugg S, Votier SC, Chapman JW, Boos M, Liechti F (2019). Size matters in quantitative radar monitoring of animal migration: estimating monitored volume from wingbeat frequency.
Ecography,
42(5), 931-941.
Abstract:
Size matters in quantitative radar monitoring of animal migration: estimating monitored volume from wingbeat frequency
Quantitative radar studies are an important component of studying the movements of birds. Whether a bird, at a certain distance from the radar, is detected or not depends on its size. The volume monitored by the radar is therefore different for birds of different sizes. Consequently, an accurate quantification of bird movements recorded by small-scale radar requires an accurate determination of the monitored volume for the objects in question, although this has tended to be ignored. Here, we demonstrate the importance of sensitivity settings for echo detection on the estimated movement intensities of birds of different sizes. The amount of energy reflected from a bird and detected by the radar receiver (echo power) depends not only on the bird's size and on the distance from the radar antenna, but also on the beam shape and the bird's position within this beam. We propose a method to estimate the size of a bird based on the wingbeat frequency, retrieved from the echo-signal, independent of the absolute echo power. The estimated bird-size allows calculation of size-specific monitored volumes, allowing accurate quantification of movement intensities. We further investigate the importance of applying size-specific monitored volumes to quantify avian movements instead of using echo counts. We also highlight the importance of accounting for size-specific monitored volume of small scale radar systems, and the necessity of reporting technical information on radar parameters. Applying this framework will increase the quality and validity of quantitative radar monitoring.
Abstract.
Shamoun-Baranes J, Nilsson C, Bauer S, Chapman J (2019). Taking radar aeroecology into the 21st century. Ecography, 42(5), 847-851.
Bauer S, Shamoun-Baranes J, Nilsson C, Farnsworth A, Kelly JF, Reynolds DR, Dokter AM, Krauel JF, Petterson LB, Horton KG, et al (2019). The grand challenges of migration ecology that radar aeroecology can help answer.
Ecography,
42(5), 861-875.
Abstract:
The grand challenges of migration ecology that radar aeroecology can help answer
Many migratory species have experienced substantial declines that resulted from rapid and massive expansions of human structures and activities, habitat alterations and climate change. Migrants are also recognized as an integral component of biodiversity and provide a multitude of services and disservices that are relevant to human agriculture, economy and health. The plethora of recently published studies reflects the need for better fundamental knowledge on migrations and for better management of their ecological and human-relevant effects. Yet, where are we in providing answers to fundamental questions and societal challenges?. Engaging a broad network of researchers worldwide, we used a horizon-scan approach to identify the most important challenges which need to be overcome in order to gain a fuller understanding of migration ecology, and which could be addressed using radar aeroecological and macroecological approaches. The top challenges include both long-standing and novel topics, ranging from fundamental information on migration routes and phenology, orientation and navigation strategies, and the multitude of effects migrants may have on resident communities, to societal challenges, such as protecting or preventing migrant services and disservices, and the conservation of migrants in the face of environmental changes. We outline these challenges, identify the urgency of addressing them and the primary stakeholders – researchers, policy makers and practitioners, or funders of research.
Abstract.
Lehmann T, Yaro A, Lamissa Z, Djibril S, Diallo M, Yossi O, Huestis DL, Linton YM, Mitchell R, Krajacich B, et al (2019). WINDBORNE LONG-DISTANCE MIGRATION OF MOSQUITOES AND PATHOGENS: IMPLICATIONS FOR MALARIA ELIMINATION.
Author URL.
2018
Nilsson C, Dokter AM, Schmid B, Scacco M, Verlinden L, Bäckman J, Haase G, Dell’Omo G, Chapman JW, Leijnse H, et al (2018). Field validation of radar systems for monitoring bird migration.
Journal of Applied Ecology,
55(6), 2552-2564.
Abstract:
Field validation of radar systems for monitoring bird migration
Advances in information technology are increasing the use of radar as a tool to investigate and monitor bird migration movements. We set up a field campaign to compare and validate outputs from different radar systems. Here we compare the pattern of nocturnal bird migration movements recorded by four different radar systems at a site in southern Sweden. Within the range of the weather radar (WR) Ängelholm, we operated a “BirdScan” (BS) dedicated bird radar, a standard marine radar (MR), and a tracking radar (TR). The measures of nightly migration intensities, provided by three of the radars (WR, BS, MR), corresponded well with respect to the relative seasonal course of migration, while absolute migration intensity agreed reasonably only between WR and BS. Flight directions derived from WR, BS and TR corresponded very well, despite very different sample sizes. Estimated mean ground speeds differed among all four systems. The correspondence among systems was highest under clear sky conditions and at high altitudes. Synthesis and applications. While different radar systems can provide useful information on nocturnal bird migration, they have distinct strengths and weaknesses, and all require supporting data to allow for species level inference. Weather radars continuously detect avian biomass flows across a wide altitude band, making them a useful tool for monitoring and predictive applications at regional to continental scales that do not rely on resolving individuals. BirdScan and marine radar’s strengths are in local and low altitude applications, such as collision risks with man-made structures and airport safety, although marine radars should not be trusted for absolute intensities of movement. In quantifying flight behaviour of individuals, tracking radars are the most informative.
Abstract.
Jones CM, Lim KS, Chapman JW, Bass C (2018). Genome-Wide Characterization of DNA Methylation in an Invasive Lepidopteran Pest, the Cotton Bollworm Helicoverpa armigera.
G3 (Bethesda),
8(3), 779-787.
Abstract:
Genome-Wide Characterization of DNA Methylation in an Invasive Lepidopteran Pest, the Cotton Bollworm Helicoverpa armigera.
The genes and genomes of insect pests are shaped by the wide array of selective forces encountered in their environments. While the molecular adaptations that evolve are beginning to be understood at the genomic and transcriptomic level, they have been less well characterized at an epigenetic level. Here, we present a genome-wide map of DNA methylation at single-nucleotide resolution for the cotton bollworm moth, Helicoverpa armigera, a globally invasive pest of agriculture. We show that methylation is almost identical in the larvae and adults of H. armigera and that, through whole-genome bisulfite sequencing (WGBS), at the most ∼0.9% of CpG sites in this species are methylated. We find that DNA methylation occurs primarily in exons, is positively correlated with gene expression, and that methylated genes are enriched for cellular "housekeeping" roles. H. armigera has an exceptional capacity for long-range migration. To explore the role of methylation in influencing the migratory phenotype of H. armigera, we performed targeted bisulfite sequencing on selected loci from 16 genes that were differentially expressed between adult moths exhibiting distinct flight performance in behavioral assays. While most CpG sites in these genes were not methylated between flight phenotypes, we identified hypermethylation in a demethylase (KDM4) that targets lysine-specific histone modifications, which are strongly associated with transcription and methylation. The H. armigera methylome provides new insights into the role of DNA methylation in a noctuid moth and is a valuable resource for further research into the epigenetic control of adaptive traits in this important pest.
Abstract.
Author URL.
Dällenbach LJ, Glauser A, Lim KS, Chapman JW, Menz MHM (2018). Higher flight activity in the offspring of migrants compared to residents in a migratory insect.
Proceedings of the Royal Society B: Biological Sciences,
285(1881).
Abstract:
Higher flight activity in the offspring of migrants compared to residents in a migratory insect
Migration has evolved among many animal taxa and migratory species are found across all major lineages. Insects are the most abundant and diverse terrestrial migrants, with trillions of animals migrating annually. Partial migration, where populations consist of resident and migratory individuals, is ubiquitous among many taxa. However, the underlying mechanisms are relatively poorly understood and may be driven by physiological, behavioural or genetic variation within populations. We investigated the differences in migratory tendency between migratory and resident phenotypes of the hoverfly, Episyrphus balteatus, using tethered flight mills. Further, to test whether migratory flight behaviour is heritable and to disentangle the effects of environment during development, we compared the flight behaviour of laboratory-reared offspring of migrating, overwintering and summer animals. Offspring of migrants initiated more flights than those of resident individuals. Interestingly, there were no differences among wild-caught phenotypes with regard to number of flights or total flight duration. Low activity in field-collected migrants might be explained by an energy-conserving state that migrants enter into when under laboratory conditions, or a lack of suitable environmental cues for triggering migration. Our results strongly suggest that flight behaviour is heritable and that genetic factors influence migratory tendency in E. balteatus. These findings support the growing evidence that genetic factors play a role in partial migration and warrant careful further investigation.
Abstract.
Hu G, Lu MH, Reynolds DR, Wang HK, Chen X, Liu WC, Zhu F, Wu XW, Xia F, Xie MC, et al (2018). Long-term seasonal forecasting of a major migrant insect pest: the brown planthopper in the Lower Yangtze River Valley.
Journal of Pest ScienceAbstract:
Long-term seasonal forecasting of a major migrant insect pest: the brown planthopper in the Lower Yangtze River Valley
© 2018, the Author(s). Rice planthoppers and associated virus diseases have become the most important pests threatening food security in China and other Asian countries, incurring costs of hundreds of millions of US dollars annually in rice losses, and in expensive, environmentally harmful, and often futile control efforts. The most economically damaging species, the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae), cannot overwinter in temperate East Asia, and infestations there are initiated by several waves of windborne spring or summer migrants originating from tropical areas in Indochina. The interaction of these waves of migrants and synoptic weather patterns, driven by the semi-permanent western Pacific subtropical high-pressure (WPSH) system, is of critical importance in forecasting the timing and intensity of immigration events and determining the seriousness of subsequent planthopper build-up in the rice crop. We analysed a 26-year data set from a standardised light trap network in Southern China, showing that planthopper aerial transport and concentration processes are associated with the characteristics (strength and position) of the WPSH in the year concerned. Then, using N. lugens abundance in source areas and indices of WPSH intensity or related sea surface temperature anomalies, we developed a model to predict planthopper numbers immigrating into the key rice-growing area of the Lower Yangtze Valley. We also demonstrate that these WPSH-related climatic indices combined with early-season planthopper catches can be used to forecast, several months in advance, the severity of that season’s N. lugens infestations (the correlation between model predictions and outcomes was 0.59), thus allowing time for effective control measures to be implemented.
Abstract.
Nilsson C, Dokter AM, Verlinden L, Shamoun-Baranes J, Schmid B, Desmet P, Bauer S, Chapman J, Alves JA, Stepanian PM, et al (2018). Revealing patterns of nocturnal migration using the European weather radar network.
EcographyAbstract:
Revealing patterns of nocturnal migration using the European weather radar network
© 2018 the Authors Nocturnal avian migration flyways remain an elusive concept, as we have largely lacked methods to map their full extent. We used the network of European weather radars to investigate nocturnal bird movements at the scale of the European flyway. We mapped the main migration directions and showed the intensity of movement across part of Europe by extracting biological information from 70 weather radar stations from northern Scandinavia to Portugal, during the autumn migration season of 2016. On average, over the 20 nights and all sites, 389 birds passed per 1 km transect per hour. The night with highest migration intensity showed an average of 1621 birds km–1 h–1 passing the radar stations, but there was considerable geographical and temporal variation in migration intensity. The highest intensity of migration was seen in central France. The overall migration directions showed strong southwest components. Migration dynamics were strongly related to synoptic wind conditions. A wind-related mass migration event occurred immediately after a change in wind conditions, but quickly diminished even when supporting winds continued to prevail. This first continental-scale study using the European network of weather radars demonstrates the wealth of information available and its potential for investigating large-scale bird movements, with consequences for ecosystem function, nutrient transfer, human and livestock health, and civil and military aviation.
Abstract.
Reynolds DR, Chapman JW, Drake VA (2018). Riders on the wind: the aeroecology of insect migrants. In (Ed)
Aeroecology, 145-178.
Abstract:
Riders on the wind: the aeroecology of insect migrants
Abstract.
Minter M, Pearson A, Lim KS, Wilson K, Chapman JW, Jones CM (2018). The tethered flight technique as a tool for studying life-history strategies associated with migration in insects.
Ecological Entomology,
43(4), 397-411.
Abstract:
The tethered flight technique as a tool for studying life-history strategies associated with migration in insects
1. Every year billions of insects engage in long-distance, seasonal mass migrations which have major consequences for agriculture, ecosystem services and insect-vectored diseases. Tracking this movement in the field is difficult, with mass migrations often occurring at high altitudes and over large spatial scales. 2. As such, tethered flight provides a valuable tool for studying the flight behaviour of insects, giving insights into flight propensity (e.g. distance, duration and velocity) and orientation under controlled laboratory settings. By experimentally manipulating a variety of environmental and physiological traits, numerous studies have used this technology to study the flight behaviour of migratory insects ranging in size from aphids to butterflies. Advances in functional genomics promise to extend this to the identification of genetic factors associated with flight. Tethered flight techniques have been used to study migratory flight characteristics in insects for more than 50 years, but have never been reviewed. 3. This study summarises the key findings of this technology, which has been employed in studies of species from six Orders. By providing detailed descriptions of the tethered flight systems, the present study also aims to further the understanding of how tethered flight studies support field observations, the situations under which the technology is useful and how it might be used in future studies. 4. The aim is to contextualise the available tethered flight studies within the broader knowledge of insect migration and to describe the significant contribution these systems have made to the literature.
Abstract.
2017
Palmer G, Platts PJ, Brereton T, Chapman JW, Dytham C, Fox R, Pearce-Higgins JW, Roy DB, Hill JK, Thomas CD, et al (2017). Climate change, climatic variation and extreme biological responses.
Philos Trans R Soc Lond B Biol Sci,
372(1723).
Abstract:
Climate change, climatic variation and extreme biological responses.
Extreme climatic events could be major drivers of biodiversity change, but it is unclear whether extreme biological changes are (i) individualistic (species- or group-specific), (ii) commonly associated with unusual climatic events and/or (iii) important determinants of long-term population trends. Using population time series for 238 widespread species (207 Lepidoptera and 31 birds) in England since 1968, we found that population 'crashes' (outliers in terms of species' year-to-year population changes) were 46% more frequent than population 'explosions'. (i) Every year, at least three species experienced extreme changes in population size, and in 41 of the 44 years considered, some species experienced population crashes while others simultaneously experienced population explosions. This suggests that, even within the same broad taxonomic groups, species are exhibiting individualistic dynamics, most probably driven by their responses to different, short-term events associated with climatic variability. (ii) Six out of 44 years showed a significant excess of species experiencing extreme population changes (5 years for Lepidoptera, 1 for birds). These 'consensus years' were associated with climatically extreme years, consistent with a link between extreme population responses and climatic variability, although not all climatically extreme years generated excess numbers of extreme population responses. (iii) Links between extreme population changes and long-term population trends were absent in Lepidoptera and modest (but significant) in birds. We conclude that extreme biological responses are individualistic, in the sense that the extreme population changes of most species are taking place in different years, and that long-term trends of widespread species have not, to date, been dominated by these extreme changes.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events'.
Abstract.
Author URL.
Bauer S, Chapman JW, Reynolds DR, Alves JA, Dokter AM, Menz MMH, Sapir N, Ciach M, Pettersson LB, Kelly JF, et al (2017). From Agricultural Benefits to Aviation Safety: Realizing the Potential of Continent-Wide Radar Networks.
BioScience,
67(10), 912-918.
Abstract:
From Agricultural Benefits to Aviation Safety: Realizing the Potential of Continent-Wide Radar Networks
Migratory animals provide a multitude of services and disservices-with benefits or costs in the order of billions of dollars annually. Monitoring, quantifying, and forecasting migrations across continents could assist diverse stakeholders in utilizing migrant services, reducing disservices, or mitigating human-wildlife conflicts. Radars are powerful tools for such monitoring as they can assess directional intensities, such as migration traffic rates, and biomass transported. Currently, however, most radar applications are local or small scale and therefore substantially limited in their ability to address large-scale phenomena. As weather radars are organized into continent-wide networks and also detect "biological targets," they could routinely monitor aerial migrations over the relevant spatial scales and over the timescales required for detecting responses to environmental perturbations. To tap these unexploited resources, a concerted effort is needed among diverse fields of expertise and among stakeholders to recognize the value of the existing infrastructure and data beyond weather forecasting.
Abstract.
Chapman JW (2017). Honey buzzards don't always make a beeline.
Journal of Animal Ecology,
86(2), 173-175.
Abstract:
Honey buzzards don't always make a beeline
(Figure presented.) (a) European honey buzzards breeding in Western Europe primarily use soaring flight to make annual long-range migrations via the Strait of Gibraltar to winter in West Africa; this adult male was photographed on migration near Gibraltar. Photo: Javier Elloriaga. (b) Autumn migration routes of 12 satellite tagged adult European honey buzzards (colour-coded lines); compared with the shortest possible straight-line routes (dashed lines), most routes involved substantial westerly detours in Africa. Adapted from Vansteelant et al. (2016). (c) in contrast, Montagu's harriers predominantly use flapping flight during their migrations; this adult male is carrying a satellite transmitter. Photo: Theo van Kooten. (d) Autumn migration routes of 34 satellite tagged adult Montagu's harriers; migratory tracks more closely approached straight-line routes, and typically involved longer sea crossings, than seen in European honey buzzards. Adapted from Trierweiler et al. (). In Focus: Vansteelant, W.M.G. Shamoun-Baranes, J. van Manen, W. van Diermen, J. & Bouten, W. (2017) Seasonal detours by soaring migrants shaped by wind regimes along the East Atlantic Flyway. Journal of Animal Ecology, 86, 179–191. Migratory birds often make substantial detours from the shortest possible route during their annual migrations, which may potentially increase the duration and energetic cost of their journeys. Vansteelant et al. () investigate repeated migrations of adult European honey buzzards between the Netherlands and sub-Saharan Africa, and find that they make large westerly detours in Africa on both the spring and autumn routes. These detours allow migrants to capitalise on more favourable winds further along the route, thus reducing energy expenditure. Lifelong tracking studies will allow researchers to identify how migration routes have evolved to exploit predictable atmospheric and oceanic circulation patterns.
Abstract.
Mauchline AL, Cook SM, Powell W, Chapman JW, Osborne JL (2017). Migratory flight behaviour of the pollen beetle Meligethes aeneus.
Pest Manag Sci,
73(6), 1076-1082.
Abstract:
Migratory flight behaviour of the pollen beetle Meligethes aeneus.
BACKGROUND: the field ecology of the pollen beetle Meligethes aeneus and its damaging effects on oilseed rape crops are well understood. However, the flight behaviour of M. aeneus, in particular the drivers for migratory movements across the landscape, is not well studied. We combined three established methodologies - suction traps, vertical-looking radar and high-altitude aerial netting - to demonstrate that M. aeneus flies at a range of altitudes at different points during its active season. RESULTS: By linking evidence of high-altitude mass migration with immigration of pollen beetles into oilseed rape fields, we were able to 'ground-truth' the results to characterise the seasonal movements of this pest across the landscape. CONCLUSION: We demonstrate that this novel combination of methodologies can advance our understanding of the population movements of pollen beetles and could provide an opportunity to develop predictive models to estimate the severity and timing of pest outbreaks. © 2017 the Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Abstract.
Author URL.
Drake VA, Chapman JW, Lim KS, Reynolds DR, Riley JR, Smith AD (2017). Ventral-aspect radar cross sections and polarization patterns of insects at X band and their relation to size and form.
INTERNATIONAL JOURNAL OF REMOTE SENSING,
38(18), 5022-5044.
Author URL.
Lehmann T, Huestis D, Yaro A, Florio J, Diallo M, Sanogo Z, Djibril S, Faiman R, Chapman JW, Reynolds DR, et al (2017). WIND-ASSISTED LONG-DISTANCE MIGRATION OF MALARIA MOSQUITOES IN THE SAHEL.
AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE,
95(5), 209-209.
Author URL.
Reynolds DR, Chapman JW, Stewart AJA (2017). Windborne migration of Auchenorrhyncha (Hemiptera) over Britain.
EUROPEAN JOURNAL OF ENTOMOLOGY,
114, 554-564.
Author URL.
2016
Hu G, Lim KS, Horvitz N, Clark SJ, Reynolds DR, Sapir N, Chapman JW (2016). Mass seasonal bioflows of high-flying insect migrants.
Science,
354(6319), 1584-1587.
Abstract:
Mass seasonal bioflows of high-flying insect migrants.
Migrating animals have an impact on ecosystems directly via influxes of predators, prey, and competitors and indirectly by vectoring nutrients, energy, and pathogens. Although linkages between vertebrate movements and ecosystem processes have been established, the effects of mass insect "bioflows" have not been described. We quantified biomass flux over the southern United Kingdom for high-flying (>150 meters) insects and show that ~3.5 trillion insects (3200 tons of biomass) migrate above the region annually. These flows are not randomly directed in insects larger than 10 milligrams, which exploit seasonally beneficial tailwinds. Large seasonal differences in the southward versus northward transfer of biomass occur in some years, although flows were balanced over the 10-year period. Our long-term study reveals a major transport process with implications for ecosystem services, processes, and biogeochemistry.
Abstract.
Author URL.
Reynolds AM, Reynolds DR, Sane SP, Hu G, Chapman JW (2016). Orientation in high-flying migrant insects in relation to flows: Mechanisms and strategies.
Philosophical Transactions of the Royal Society B: Biological Sciences,
371(1704).
Abstract:
Orientation in high-flying migrant insects in relation to flows: Mechanisms and strategies
High-flying insect migrants have been shown to display sophisticated flight orientations that can, for example, maximize distance travelled by exploiting tailwinds, and reduce drift from seasonally optimal directions. Here, we provide a comprehensive overview of the theoretical and empirical evidence for the mechanisms underlying the selection and maintenance of the observed flight headings, and the detection of wind direction and speed, for insects flying hundreds of metres above the ground. Different mechanisms may be used—visual perception of the apparent ground movement or mechanosensory cues maintained by intrinsic features of the wind—depending on circumstances (e.g. day or night migrations). In addition to putative turbulence-induced velocity, acceleration and temperature cues, we present a new mathematical analysis which shows that ‘jerks’ (the time-derivative of accelerations) can provide indicators of wind direction at altitude. The adaptive benefits of the different orientation strategies are briefly discussed, and we place these newfindings for insects within a wider context by comparisons with the latest research on other flying and swimming organisms.
Abstract.
Palmer G, Hill JK, Brereton TM, Brooks DR, Chapman JW, Fox R, Oliver TH, Thomas CD (2016). Retraction of the Research Article: "Individualistic sensitivities and exposure to climate change explain variation in species' distribution and abundance changes".
Sci Adv,
2(4).
Abstract:
Retraction of the Research Article: "Individualistic sensitivities and exposure to climate change explain variation in species' distribution and abundance changes".
[This retracts the article on p. e1400220 in vol. 1, PMID: 26601276.].
Abstract.
Author URL.
Hu G, Lim KS, Reynolds DR, Reynolds AM, Chapman JW (2016). Wind-related orientation patterns in diurnal, crepuscular and nocturnal high-altitude insect migrants.
Frontiers in Behavioral Neuroscience,
10Abstract:
Wind-related orientation patterns in diurnal, crepuscular and nocturnal high-altitude insect migrants
© 2016 Hu, Lim, Reynolds, Reynolds and Chapman. Most insect migrants fly at considerable altitudes (hundreds of meters above the ground) where they utilize fast-flowing winds to achieve rapid and comparatively long- distance transport. The nocturnal aerial migrant fauna has been well studied with entomological radars, and many studies have demonstrated that flight orientations are frequently grouped around a common direction in a range of nocturnal insect migrants. Common orientation typically occurs close to the downwind direction (thus ensuring that a large component of the insects’ self-powered speed is directed downstream), and in nocturnal insects at least, the downwind headings are seemingly maintained by direct detection of wind-related turbulent cues. Despite being far more abundant and speciose, the day-flying windborne migrant fauna has been much less studied by radar; thus the frequency of wind-related common orientation patterns and the sensory mechanisms involved in their formation remain to be established. Here, we analyze a large dataset of >600,000 radar-detected “medium-sized” windborne insect migrants (body mass from 10 to 70 mg), flying hundreds of meters above southern UK, during the afternoon, in the period around sunset, and in the middle of the night. We found that wind-related common orientation was almost ubiquitous during the day (present in 97% of all “migration events” analyzed), and was also frequent at sunset (85%) and at night (81%). Headings were systematically offset to the right of the flow at night-time (as predicted from the use of turbulence cues for flow assessment), but there was no directional bias in the offsets during the day or at sunset. Orientation “performance” significantly increased with increasing flight altitude throughout the day and night. We conclude by discussing sensory mechanisms which most likely play a role in the selection and maintenance of wind-related flight headings.
Abstract.
2015
Chapman JW, Nilsson C, Lim KS, Bäckman J, Reynolds DR, Alerstam T (2015). Adaptive strategies in nocturnally migrating insects and songbirds: Contrasting responses to wind.
Journal of Animal Ecology,
85(1), 115-124.
Abstract:
Adaptive strategies in nocturnally migrating insects and songbirds: Contrasting responses to wind
© 2016 British Ecological Society. Animals that use flight as their mode of transportation must cope with the fact that their migration and orientation performance is strongly affected by the flow of the medium they are moving in, that is by the winds. Different strategies can be used to mitigate the negative effects and benefit from the positive effects of a moving flow. The strategies an animal can use will be constrained by the relationship between the speed of the flow and the speed of the animal's own propulsion in relation to the surrounding air. Here we analyse entomological and ornithological radar data from north-western Europe to investigate how two different nocturnal migrant taxa, the noctuid moth Autographa gamma and songbirds, deal with wind by analysing variation in resulting flight directions in relation to the wind-dependent angle between the animal's heading and track direction. Our results, from fixed locations along the migratory journey, reveal different global strategies used by moths and songbirds during their migratory journeys. As expected, nocturnally migrating moths experienced a greater degree of wind drift than nocturnally migrating songbirds, but both groups were more affected by wind in autumn than in spring. The songbirds' strategies involve elements of both drift and compensation, providing some benefits from wind in combination with destination and time control. In contrast, moths expose themselves to a significantly higher degree of drift in order to obtain strong wind assistance, surpassing the songbirds in mean ground speed, at the cost of a comparatively lower spatiotemporal migratory precision. Moths and songbirds show contrasting but adaptive responses to migrating through a moving flow, which are fine-tuned to the respective flight capabilities of each group in relation to the wind currents they travel within.
Abstract.
Chapman JW, Nilsson C, Lim KS, Bäckman J, Reynolds DR, Alerstam T, Reynolds AM (2015). Detection of flow direction in high-flying insect and songbird migrants.
Current Biology,
25(17), R751-R752.
Abstract:
Detection of flow direction in high-flying insect and songbird migrants
Goal-oriented migrants travelling through the sea or air must cope with the effect of cross-flows during their journeys if they are to reach their destination [1-3]. In order to counteract flow-induced drift from their preferred course, migrants must detect the mean flow direction, and integrate this information with output from their internal compass, to compensate for the deflection. Animals can potentially sense flow direction by two nonexclusive mechanisms: either indirectly, by visually assessing the effect of the current on their movement direction relative to the ground; or directly, via intrinsic properties of the current [4]. Here, we report the first evidence that nocturnal compass-guided insect migrants use a turbulence-mediated mechanism for directly assessing the wind direction hundreds of metres above the ground. By comparison, we find that nocturnally-migrating songbirds do not use turbulence to detect the flow; instead they rely on visual assessment of wind-induced drift to indirectly infer the flow direction.
Abstract.
Reynolds AM, Jones HBC, Hill JK, Pearson AJ, Wilson K, Wolf S, Lim KS, Reynolds DR, Chapman JW (2015). Evidence for a pervasive ‘idling-mode’ activity template in flying and pedestrian insects.
Royal Society Open Science,
2(5).
Abstract:
Evidence for a pervasive ‘idling-mode’ activity template in flying and pedestrian insects
©2015 the Authors. Understanding the complex movement patterns of animals in natural environments is a key objective of ‘movement ecology’. Complexity results from behavioural responses to external stimuli but can also arise spontaneously in their absence. Drawing on theoretical arguments about decision-making circuitry, we predict that the spontaneous patterns will be scale-free and universal, being independent of taxon and mode of locomotion. To test this hypothesis, we examined the activity patterns of the European honeybee, and multiple species of noctuid moth, tethered to flight mills and exposed to minimal external cues. We also reanalysed pre-existing data for Drosophila flies walking in featureless environments. Across these species, we found evidence of common scale-invariant properties in their movement patterns; pause and movement durations were typically power law distributed over a range of scales and characterized by exponents close to 3/2. Our analyses are suggestive of the presence of a pervasive scale-invariant template for locomotion which, when acted on by environmental cues, produces the movements with characteristic scales observed in nature. Our results indicate that scale-finite complexity as embodied, for instance, in correlatedrandom walk models, may be the result of environmental cues overriding innate behaviour, and that scale-free movements may be intrinsic and not limited to ‘blind’ foragers as previously thought.
Abstract.
Gürbüz SZ, Reynolds DR, Koistinen J, Liechti F, Leijnse H, Shamoun-Baranes J, Dokter AM, Kelly J, Chapman JW (2015). Exploring the skies: Technological challenges in radar aeroecology.
Abstract:
Exploring the skies: Technological challenges in radar aeroecology
Abstract.
Jones CM, Papanicolaou A, Mironidis GK, Vontas J, Yang Y, Lim KS, Oakeshott JG, Bass C, Chapman JW (2015). Genomewide transcriptional signatures of migratory flight activity in a globally invasive insect pest.
MOLECULAR ECOLOGY,
24(19), 4901-4911.
Author URL.
Palmer G, Hill JK, Brereton TM, Brooks DR, Chapman JW, Fox R, Oliver TH, Thomas CD (2015). Individualistic sensitivities and exposure to climate change explain variation in species' distribution and abundance changes.
Sci Adv,
1(9).
Abstract:
Individualistic sensitivities and exposure to climate change explain variation in species' distribution and abundance changes.
The responses of animals and plants to recent climate change vary greatly from species to species, but attempts to understand this variation have met with limited success. This has led to concerns that predictions of responses are inherently uncertain because of the complexity of interacting drivers and biotic interactions. However, we show for an exemplar group of 155 Lepidoptera species that about 60% of the variation among species in their abundance trends over the past four decades can be explained by species-specific exposure and sensitivity to climate change. Distribution changes were less well predicted, but nonetheless, up to 53% of the variation was explained. We found that species vary in their overall sensitivity to climate and respond to different components of the climate despite ostensibly experiencing the same climate changes. Hence, species have undergone different levels of population "forcing" (exposure), driving variation among species in their national-scale abundance and distribution trends. We conclude that variation in species' responses to recent climate change may be more predictable than previously recognized.
Abstract.
Author URL.
Chapman JW, Reynolds DR, Wilson K (2015). Long-range seasonal migration in insects: Mechanisms, evolutionary drivers and ecological consequences.
Ecology Letters,
18(3), 287-302.
Abstract:
Long-range seasonal migration in insects: Mechanisms, evolutionary drivers and ecological consequences
Myriad tiny insect species take to the air to engage in windborne migration, but entomology also has its 'charismatic megafauna' of butterflies, large moths, dragonflies and locusts. The spectacular migrations of large day-flying insects have long fascinated humankind, and since the advent of radar entomology much has been revealed about high-altitude night-time insect migrations. Over the last decade, there have been significant advances in insect migration research, which we review here. In particular, we highlight: (1) notable improvements in our understanding of lepidopteran navigation strategies, including the hitherto unsuspected capabilities of high-altitude migrants to select favourable winds and orientate adaptively, (2) progress in unravelling the neuronal mechanisms underlying sun compass orientation and in identifying the genetic complex underpinning key traits associated with migration behaviour and performance in the monarch butterfly, and (3) improvements in our knowledge of the multifaceted interactions between disease agents and insect migrants, in terms of direct effects on migration success and pathogen spread, and indirect effects on the evolution of migratory systems. We conclude by highlighting the progress that can be made through inter-phyla comparisons, and identify future research areas that will enhance our understanding of insect migration strategies within an eco-evolutionary perspective.
Abstract.
Jones HBC, Lim KS, Bell JR, Hill JK, Chapman JW (2015). Quantifying interspecific variation in dispersal ability of noctuid moths using an advanced tethered flight technique.
Ecology and Evolution,
6(1), 181-190.
Abstract:
Quantifying interspecific variation in dispersal ability of noctuid moths using an advanced tethered flight technique
© 2016 Published by John Wiley. &. Sons Ltd. Dispersal plays a crucial role in many aspects of species' life histories, yet is often difficult to measure directly. This is particularly true for many insects, especially nocturnal species (e.g. moths) that cannot be easily observed under natural field conditions. Consequently, over the past five decades, laboratory tethered flight techniques have been developed as a means of measuring insect flight duration and speed. However, these previous designs have tended to focus on single species (typically migrant pests), and here we describe an improved apparatus that allows the study of flight ability in a wide range of insect body sizes and types. Obtaining dispersal information from a range of species is crucial for understanding insect population dynamics and range shifts. Our new laboratory tethered flight apparatus automatically records flight duration, speed, and distance of individual insects. The rotational tethered flight mill has very low friction and the arm to which flying insects are attached is extremely lightweight while remaining rigid and strong, permitting both small and large insects to be studied. The apparatus is compact and thus allows many individuals to be studied simultaneously under controlled laboratory conditions. We demonstrate the performance of the apparatus by using the mills to assess the flight capability of 24 species of British noctuid moths, ranging in size from 12-27 mm forewing length (~40-660 mg body mass). We validate the new technique by comparing our tethered flight data with existing information on dispersal ability of noctuids from the published literature and expert opinion. Values for tethered flight variables were in agreement with existing knowledge of dispersal ability in these species, supporting the use of this method to quantify dispersal in insects. Importantly, this new technology opens up the potential to investigate genetic and environmental factors affecting insect dispersal among a wide range of species.
Abstract.
2014
Shamoun-Baranes J, Alves JA, Bauer S, Dokter AM, Hüppop O, Koistinen J, Leijnse H, Liechti F, Gasteren HV, Chapman JW, et al (2014). Continental-scale radar monitoring of the aerial movements of animals.
Movement Ecology,
2(1).
Abstract:
Continental-scale radar monitoring of the aerial movements of animals
Billions of organisms travel through the air, influencing population dynamics, community interactions, ecosystem services and our lives in many different ways. Yet monitoring these movements are technically very challenging. During the last few decades, radars have increasingly been used to study the aerial movements of birds, bats and insects, yet research efforts have often been local and uncoordinated between research groups. However, a network of operational weather radars is continuously recording atmospheric conditions all over Europe and these hold enormous potential for coordinated, continental-scale studies of the aerial movements of animals. The European Network for the Radar surveillance of Animal Movement (ENRAM) is a new e-COST research network aiming exactly at exploring this potential. The main objective of ENRAM is to merge expertise to utilize weather radars to monitor the aerial movement of animals across Europe for a broad range of stakeholders at an unprecedented scale and enable researchers to study the causes and consequences of movement. In this paper we describe the aims of ENRAM in more detail and the challenges researchers will address, provide an overview of aero-ecological studies using radar, and present some of the opportunities that a large sensor network can provide for movement ecology research.
Abstract.
Reynolds DR, Reynolds AM, Chapman JW (2014). Non-volant modes of migration in terrestrial arthropods. Animal Migration, 2(1), 8-28.
Fu XW, Li C, Feng HQ, Liu ZF, Chapman JW, Reynolds DR, Wu KM (2014). Seasonal migration of Cnaphalocrocis medinalis (Lepidoptera: Crambidae) over the Bohai Sea in Northern China.
Bulletin of Entomological Research,
104(5), 601-609.
Abstract:
Seasonal migration of Cnaphalocrocis medinalis (Lepidoptera: Crambidae) over the Bohai Sea in Northern China
The rice leaf roller, Cnaphalocrocis medinalis (Guenée), is a serious insect pest of rice with a strong migratory ability. Previous studies on the migration of C. medinalis were mostly carried out in tropical or subtropical regions, however, and what the pattern of seasonal movements this species exhibits in temperate regions (i.e. Northern China, where they cannot overwinter) remains unknown. Here we present data from an 11-year study of this species made by searchlight trapping on Beihuang Island (BH, 38°24'N; 120° 55'E) in the centre of the Bohai Strait, which provides direct evidence that C. medinalis regularly migrates across this sea into northeastern agricultural region of China, and to take advantage of the abundant food resources there during the summer season. There was considerable seasonal variation in number of C. medinalis trapped on BH, and the migration period during 2003-2013 ranged from 72 to 122 days. Some females trapped in June and July showed a relatively higher proportion of mated and a degree of ovarian development suggesting that the migration of this species is not completely bound by the 'oogenesis-flight syndrome'. These findings revealed a new route for C. medinalis movements to and from Northeastern China, which will help us develop more effective management strategies against this pest.
Abstract.
2013
Jeffries DL, Chapman J, Roy HE, Humphries S, Harrington R, Brown PMJ, Handley L-JL (2013). Characteristics and drivers of high-altitude ladybird flight: insights from vertical-looking entomological radar.
PLoS One,
8(12).
Abstract:
Characteristics and drivers of high-altitude ladybird flight: insights from vertical-looking entomological radar.
Understanding the characteristics and drivers of dispersal is crucial for predicting population dynamics, particularly in range-shifting species. Studying long-distance dispersal in insects is challenging, but recent advances in entomological radar offer unique insights. We analysed 10 years of radar data collected at Rothamsted Research, U.K. to investigate characteristics (altitude, speed, seasonal and annual trends) and drivers (aphid abundance, air temperature, wind speed and rainfall) of high-altitude flight of the two most abundant U.K. ladybird species (native Coccinella septempunctata and invasive Harmonia axyridis). These species cannot be distinguished in the radar data since their reflectivity signals overlap, and they were therefore analysed together. However, their signals do not overlap with other, abundant insects so we are confident they constitute the overwhelming majority of the analysed data. The target species were detected up to ∼1100 m above ground level, where displacement speeds of up to ∼60 km/h were recorded, however most ladybirds were found between ∼150 and 500 m, and had a mean displacement of 30 km/h. Average flight time was estimated, using tethered flight experiments, to be 36.5 minutes, but flights of up to two hours were observed. Ladybirds are therefore potentially able to travel 18 km in a "typical" high-altitude flight, but up to 120 km if flying at higher altitudes, indicating a high capacity for long-distance dispersal. There were strong seasonal trends in ladybird abundance, with peaks corresponding to the highest temperatures of mid-summer, and warm air temperature was the key driver of ladybird flight. Climatic warming may therefore increase the potential for long-distance dispersal in these species. Low aphid abundance was a second significant factor, highlighting the important role of aphid population dynamics in ladybird dispersal. This research illustrates the utility of radar for studying high-altitude insect flight and has important implications for predicting long-distance dispersal.
Abstract.
Author URL.
Reynolds DR, Nau BS, Chapman JW (2013). High-altitude migration of heteroptera in Britain.
European Journal of Entomology,
110(3), 483-492.
Abstract:
High-altitude migration of heteroptera in Britain
Heteroptera caught during day and night sampling at a height of 200 m above ground at Cardington, Bedfordshire, UK, during eight summers (1999, 2000, and 2002-2007) were compared to high-altitude catches made over the UK and North Sea from the 1930s to the 1950s. The height of these captures indicates that individuals were engaged in windborne migration over distances of at least several kilometres and probably tens of kilometres. This conclusion is generally supported by what is known of the species' ecologies, which reflect the view that the level of dispersiveness is associated with the exploitation of temporary habitats or resources. The seasonal timing of the heteropteran migrations is interpreted in terms of the breeding/overwintering cycles of the species concerned.
Abstract.
Stefanescu C, Páramo F, Åkesson S, Alarcón M, Ávila A, Brereton T, Carnicer J, Cassar LF, Fox R, Heliölä J, et al (2013). Multi-generational long-distance migration of insects: Studying the painted lady butterfly in the Western Palaearctic.
Ecography,
36(4), 474-486.
Abstract:
Multi-generational long-distance migration of insects: Studying the painted lady butterfly in the Western Palaearctic
Long-range, seasonal migration is a widespread phenomenon among insects, allowing them to track and exploit abundant but ephemeral resources over vast geographical areas. However, the basic patterns of how species shift across multiple locations and seasons are unknown in most cases, even though migrant species comprise an important component of the temperate-zone biota. The painted lady butterfly Vanessa cardui is such an example; a cosmopolitan continuously-brooded species which migrates each year between Africa and Europe, sometimes in enormous numbers. The migration of 2009 was one of the most impressive recorded, and thousands of observations were collected through citizen science programmes and systematic entomological surveys, such as high altitude insect-monitoring radar and ground-based butterfly monitoring schemes. Here we use V. cardui as a model species to better understand insect migration in the Western Palaearctic, and we capitalise on the complementary data sources available for this iconic butterfly. The migratory cycle in this species involves six generations, encompassing a latitudinal shift of thousands of kilometres (up to 60 degrees of latitude). The cycle comprises an annual poleward advance of the populations in spring followed by an equatorward return movement in autumn, with returning individuals potentially flying thousands of kilometres. We show that many long-distance migrants take advantage of favourable winds, moving downwind at high elevation (from some tens of metres from the ground to altitudes over 1000 m), pointing at strong similarities in the flight strategies used by V. cardui and other migrant Lepidoptera. Our results reveal the highly successful strategy that has evolved in these insects, and provide a useful framework for a better understanding of long-distance seasonal migration in the temperate regions worldwide. © 2012 the Authors. Journal compilation © 2012 Nordic Society Oikos.
Abstract.
Bell JR, Aralimarad P, Lim KS, Chapman JW (2013). Predicting Insect Migration Density and Speed in the Daytime Convective Boundary Layer.
PLoS ONE,
8(1).
Abstract:
Predicting Insect Migration Density and Speed in the Daytime Convective Boundary Layer
Insect migration needs to be quantified if spatial and temporal patterns in populations are to be resolved. Yet so little ecology is understood above the flight boundary layer (i.e. >10 m) where in north-west Europe an estimated 3 billion insects km-1 month-1 comprising pests, beneficial insects and other species that contribute to biodiversity use the atmosphere to migrate. Consequently, we elucidate meteorological mechanisms principally related to wind speed and temperature that drive variation in daytime aerial density and insect displacements speeds with increasing altitude (150-1200 m above ground level). We derived average aerial densities and displacement speeds of 1.7 million insects in the daytime convective atmospheric boundary layer using vertical-looking entomological radars. We first studied patterns of insect aerial densities and displacements speeds over a decade and linked these with average temperatures and wind velocities from a numerical weather prediction model. Generalized linear mixed models showed that average insect densities decline with increasing wind speed and increase with increasing temperatures and that the relationship between displacement speed and density was negative. We then sought to derive how general these patterns were over space using a paired site approach in which the relationship between sites was examined using simple linear regression. Both average speeds and densities were predicted remotely from a site over 100 km away, although insect densities were much noisier due to local 'spiking'. By late morning and afternoon when insects are migrating in a well-developed convective atmosphere at high altitude, they become much more difficult to predict remotely than during the early morning and at lower altitudes. Overall, our findings suggest that predicting migrating insects at altitude at distances of ≈100 km is promising, but additional radars are needed to parameterise spatial covariance. © 2013 Bell et al.
Abstract.
Chapman JW, Lim KS, Reynolds DR (2013). The significance of midsummer movements of <i>Autographa gamma</i>: Implications for a mechanistic understanding of orientation behavior in a migrant moth.
CURRENT ZOOLOGY,
59(3), 360-370.
Author URL.
2012
O'Neill BF, Bond K, Tyner A, Sheppard R, Bryant T, Chapman J, Bell J, Donnelly A (2012). Climatic change is advancing the phenology of moth species in Ireland.
ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA,
143(1), 74-88.
Author URL.
Brooks DR, Bater JE, Clark SJ, Monteith DT, Andrews C, Corbett SJ, Beaumont DA, Chapman JW (2012). Large carabid beetle declines in a United Kingdom monitoring network increases evidence for a widespread loss in insect biodiversity.
Journal of Applied Ecology,
49(5), 1009-1019.
Abstract:
Large carabid beetle declines in a United Kingdom monitoring network increases evidence for a widespread loss in insect biodiversity
Carabid beetles are important functional components of many terrestrial ecosystems. Here, we describe the first long-term, wide-scale and quantitative assessment of temporal changes in UK carabid communities, to inform nationwide management aimed at their conservation. Multivariate and mixed models were used to assess temporal trends over a 15-year period, across eleven sites in the UK Environmental Change Network. Sites covered pasture, field margins, chalk downland, woodland and hedgerows in the lowlands, moorland and pasture in the uplands, and grassland, heaths and bogs in montane locations. We found substantial overall declines in carabid biodiversity. Three-quarters of the species studied declined, half of which were estimated to be undergoing population reductions of > 30%, when averaged over 10-year periods. Declines of this magnitude are recognized to be of conservation concern. They are comparable to those reported for butterflies and moths and increase the evidence base showing that insects are undergoing serious and widespread biodiversity losses. Overall trends masked differences between regions and habitats. Carabid population declines (10-year trend, averaged across species) were estimated to be 52% in montane sites, 31% in northern moorland sites and 28% in western pasture sites (with at least 80% of species declining in each case). Conversely, populations in our southern downland site had 10-year increases of 48% on average. Overall, biodiversity was maintained in upland pasture, and populations were mostly stable in woodland and hedgerow sites. Synthesis and applications. Our results highlight the need to assess trends for carabids, and probably other widespread and ubiquitous taxa, across regions and habitats to fully understand losses in biodiversity. Land management should be underpinned by a consideration of how wide-scale environmental drivers interact with habitat structure. The stability of population trends in woodlands and hedgerows of species that are declining elsewhere puts these habitats at the fore-front of integrated landscape management aimed at preserving their ecosystem services. © 2012 the Authors. Journal of Applied Ecology © 2012 British Ecological Society.
Abstract.
Chilson PB, Bridge E, Frick WF, Chapman JW, Kelly JF (2012). Radar aeroecology: Exploring the movements of aerial fauna through radio-wave remote sensing.
Abstract:
Radar aeroecology: Exploring the movements of aerial fauna through radio-wave remote sensing
Abstract.
Chapman JW, Bell JR, Burgin LE, Reynolds DR, Pettersson LB, Hill JK, Bonsall MB, Thomas JA (2012). Seasonal migration to high latitudes results in major reproductive benefits in an insect.
Proceedings of the National Academy of Sciences of the United States of America,
109(37), 14924-14929.
Abstract:
Seasonal migration to high latitudes results in major reproductive benefits in an insect
Little is known of the population dynamics of long-range insect migrants, and it has been suggested that the annual journeys of billions of nonhardy insects to exploit temperate zones during summer represent a sink from which future generations seldom return (the "Pied Piper" effect). We combine data from entomological radars and ground-based light traps to show that annual migrations are highly adaptive in the noctuid moth Autographa gamma (silver Y), a major agricultural pest. We estimate that 10-240 million immigrants reach the United Kingdom each spring, but that summer breeding results in a fourfold increase in the abundance of the subsequent generation of adults, all of which emigrate southward in the fall. Trajectory simulations show that 80% of emigrants will reach regions suitable for winter breeding in the Mediterranean Basin, for which our population dynamics model predicts a winter carrying capacity only 20% of that of northern Europe during the summer. We conclude not only that poleward insect migrations in spring result in major population increases, but also that the persistence of such species is dependent on summer breeding in high-latitude regions, which requires a fundamental change in our understanding of insect migration.
Abstract.
2011
(2011). 10.1023/A:1003525629878. CrossRef Listing of Deleted DOIs
Chapman JW, Klaassen RHG, Drake VA, Fossette S, Hays GC, Metcalfe JD, Reynolds AM, Reynolds DR, Alerstam T (2011). Animal orientation strategies for movement in flows.
Current Biology,
21(20).
Abstract:
Animal orientation strategies for movement in flows
For organisms that fly or swim, movement results from the combined effects of the moving medium - air or water - and the organism's own locomotion. For larger organisms, propulsion contributes significantly to progress but the flow usually still provides significant opposition or assistance, or produces lateral displacement ('drift'). Animals show a range of responses to flows, depending on the direction of the flow relative to their preferred direction, the speed of the flow relative to their own self-propelled speed, the incidence of flows in different directions and the proportion of the journey remaining. We here present a classification of responses based on the direction of the resulting movement relative to flow and preferred direction, which is applicable to a range of taxa and environments. The responses adopted in particular circumstances are related to the organisms' locomotory and sensory capacities and the environmental cues available. Advances in biologging technologies and particle tracking models are now providing a wealth of data, which often demonstrate a striking level of convergence in the strategies that very different animals living in very different environments employ when moving in a flow. © 2011 Elsevier Ltd. All rights reserved.
Abstract.
Alerstam T, Chapman JW, Bäckman J, Smith AD, Karlsson H, Nilsson C, Reynolds DR, Klaassen RHG, Hill JK (2011). Convergent patterns of long-distance nocturnal migration in noctuid moths and passerine birds.
Proceedings of the Royal Society B: Biological Sciences,
278(1721), 3074-3080.
Abstract:
Convergent patterns of long-distance nocturnal migration in noctuid moths and passerine birds
Vast numbers of insects and passerines achieve long-distance migrations between summer and winter locations by undertaking high-altitude nocturnal flights. Insects such as noctuid moths fly relatively slowly in relation to the surrounding air, with airspeeds approximately one-third of that of passerines. Thus, it has been widely assumed that windborne insect migrants will have comparatively little control over their migration speed and direction compared with migrant birds. We used radar to carry out the first comparative analyses of the flight behaviour and migratory strategies of insects and birds under nearly equivalent natural conditions. Contrary to expectations, noctuid moths attained almost identical ground speeds and travel directions compared with passerines, despite their very different flight powers and sensory capacities. Moths achieved fast travel speeds in seasonally appropriate migration directions by exploiting favourably directed winds and selecting flight altitudes that coincided with the fastest air streams. By contrast, passerines were less selective of wind conditions, relying on self-powered flight in their seasonally preferred direction, often with little or no tailwind assistance. Our results demonstrate that noctuid moths and passerines show contrasting risk-prone and risk-averse migratory strategies in relation to wind. Comparative studies of the flight behaviours of distantly related taxa are critically important for understanding the evolution of animal migration strategies. © 2011 the Royal Society.
Abstract.
Bauer S, Nolet BA, Giske J, Chapman JW, Åkesson S, Hedenström A, Fryxell JM (2011). Cues and decision rules in animal migration. In (Ed) Animal Migration, Oxford University Press (OUP), 68-87.
Aralimarad P, Reynolds AM, Lim KS, Reynolds DR, Chapman JW (2011). Flight altitude selection increases orientation performance in high-flying nocturnal insect migrants.
Animal Behaviour,
82(6), 1221-1225.
Abstract:
Flight altitude selection increases orientation performance in high-flying nocturnal insect migrants
Many insects migrate at high altitudes where they utilize fast-flowing airstreams for long-distance transport. Nocturnal insect migrants typically exhibit a strongly unimodal distribution of flight headings (a phenomenon termed 'common orientation'), and the mean heading is often aligned downwind. In addition, these nocturnal migrants are sometimes concentrated into shallow altitudinal zones (termed 'layers'). The mechanism by which widely separated insects select and maintain common flight headings had until recently eluded explanation, but recent theoretical advances have shown that atmospheric turbulence might enable insects to perceive the downwind direction and orient accordingly. This theory predicts that common orientation downwind should be: (1) widespread in nocturnal insect migrants; (2) facilitated when insects are concentrated into layers; and (3) more pronounced in larger insects. We tested these ideas using radar observations of 647 independent nocturnal migration events, and found strong support for all three predictions: (1) common orientation occurred in 75-90% of events; (2) common orientation was more frequent, had significantly less scatter and was significantly closer to downwind when insects migrated in layers; and (3) large insects exhibited significantly tighter orientation than 'medium-sized' insects. Our results provide robust evidence that wind-related common orientation is mediated by detection of atmospheric turbulence. © 2011 the Association for the Study of Animal Behaviour.
Abstract.
Chapman JW, Drake VA, Reynolds DR (2011). Recent insights from radar studies of insect flight.
Annual Review of Entomology,
56, 337-356.
Abstract:
Recent insights from radar studies of insect flight
Radar has been used to study insects in flight for over 40 years and has helped to establish the ubiquity of several migration phenomena: dawn, morning, and dusk takeoffs; approximate downwind transport; concentration at wind convergences; layers in stable nighttime atmospheres; and nocturnal common orientation. Two novel radar designs introduced in the late 1990s have significantly enhanced observing capabilities. Radar-based research now encompasses foraging as well as migration and is increasingly focused on flight behavior and the environmental cues luencing it. Migrant moths have been shown to employ sophisticated orientation and height-selection strategies that maximize displacements in seasonally appropriate directions; they appear to have an internal compass and to respond to turbulence features in the airflow. Tracks of foraging insects demonstrate compensation for wind drift and use of optimal search paths to locate resources. Further improvements to observing capabilities, and employment in operational as well as research roles, appear feasible. © 2011 by Annual Reviews. All rights reserved.
Abstract.
2010
Reynolds AM, Reynolds DR, Smith AD, Chapman JW (2010). A single wind-mediated mechanism explains high-altitude 'non-goal oriented' headings and layering of nocturnally migrating insects.
Proceedings of the Royal Society B: Biological Sciences,
277(1682), 765-772.
Abstract:
A single wind-mediated mechanism explains high-altitude 'non-goal oriented' headings and layering of nocturnally migrating insects
Studies made with both entomological and meteorological radars over the last 40 years have frequently reported the occurrence of insect layers, and that the individuals forming these layers often show a considerable degree of uniformity in their headings - behaviour known as 'common orientation'. The environmental cues used by nocturnal migrants to select and maintain common headings, while flying in low illumination levels at great heights above the ground, and the adaptive benefits of this behaviour have long remained a mystery. Here we show how a wind-mediated mechanism accounts for the common orientation patterns of 'medium-sized' nocturnal insects. Our theory posits a mechanism by which migrants are able to align themselves with the direction of the flow using a turbulence cue, thus adding their air speed to the wind speed and significantly increasing their migration distance. Our mechanism also predicts that insects flying in the Northern Hemisphere will typically be offset to the right of the mean wind line when the atmosphere is stably stratified, with the Ekman spiral in full effect. We report on the first evidence for such offsets, and show that they have significant implications for the accurate prediction of the flight trajectories of migrating nocturnal insects. © 2009 the Royal Society.
Abstract.
Chapman JW, Nesbit RL, Burgin LE, Reynolds DR, Smith AD, Middleton DR, Hill JK (2010). Flight orientation behaviors promote optimal migration trajectories in high-flying insects.
Science,
327(5966), 682-685.
Abstract:
Flight orientation behaviors promote optimal migration trajectories in high-flying insects
Many insects undertake long-range seasonal migrations to exploit temporary breeding sites hundreds or thousands of kilometers apart, but the behavioral adaptations that facilitate these movements remain largely unknown. Using entomological radar, we showed that the ability to select seasonally favorable, high-altitude winds is widespread in large day- and night-flying migrants and that insects adopt optimal flight headings that partially correct for crosswind drift, thus maximizing distances traveled. Trajectory analyses show that these behaviors increase migration distances by 40% and decrease the degree of drift from seasonally optimal directions. These flight behaviors match the sophistication of those seen in migrant birds and help explain how high-flying insects migrate successfully between seasonal habitats.
Abstract.
Wood CR, Clark SJ, Barlow JF, Chapman JW (2010). Layers of nocturnal insect migrants at high-altitude: the influence of atmospheric conditions on their formation.
Agricultural and Forest Entomology,
12(1), 113-121.
Abstract:
Layers of nocturnal insect migrants at high-altitude: the influence of atmospheric conditions on their formation
Radar studies of nocturnal insect migration have often found that the migrants tend to form well-defined horizontal layers at a particular altitude. In previous short-term studies, nocturnal layers were usually observed to occur at the same altitude as certain meteorological features, most notably at the altitudes of temperature inversion tops or nocturnal wind jets. Statistical analyses are presented of 4 years of data that compared the presence, sharpness and duration of nocturnal layer profiles, observed using continuously-operating entomological radar, with meteorological variables at typical layer altitudes over the U.K. Analysis of these large datasets demonstrated that temperature was the foremost meteorological factor that was persistently associated with the presence and formation of longer-lasting and sharper layers of migrating insects over southern U.K. © 2009 the Royal Entomological Society.
Abstract.
Reynolds AM, Reynolds DR, Smith AD, Chapman JW (2010). Orientation cues for high-flying nocturnal insect migrants: Do turbulence-induced temperature and velocity fluctuations indicate the mean wind flow?.
PLoS ONE,
5(12).
Abstract:
Orientation cues for high-flying nocturnal insect migrants: Do turbulence-induced temperature and velocity fluctuations indicate the mean wind flow?
Migratory insects flying at high altitude at night often show a degree of common alignment, sometimes with quite small angular dispersions around the mean. The observed orientation directions are often close to the downwind direction and this would seemingly be adaptive in that large insects could add their self-propelled speed to the wind speed, thus maximising their displacement in a given time. There are increasing indications that high-altitude orientation may be maintained by some intrinsic property of the wind rather than by visual perception of relative ground movement. Therefore, we first examined whether migrating insects could deduce the mean wind direction from the turbulent fluctuations in temperature. Within the atmospheric boundary-layer, temperature records show characteristic ramp-cliff structures, and insects flying downwind would move through these ramps whilst those flying crosswind would not. However, analysis of vertical-looking radar data on the common orientations of nocturnally migrating insects in the UK produced no evidence that the migrants actually use temperature ramps as orientation cues. This suggests that insects rely on turbulent velocity and acceleration cues, and refocuses attention on how these can be detected, especially as small-scale turbulence is usually held to be directionally invariant (isotropic). In the second part of the paper we present a theoretical analysis and simulations showing that velocity fluctuations and accelerations felt by an insect are predicted to be anisotropic even when the small-scale turbulence (measured at a fixed point or along the trajectory of a fluid-particle) is isotropic. Our results thus provide further evidence that insects do indeed use turbulent velocity and acceleration cues as indicators of the mean wind direction. © 2010 Reynolds et al.
Abstract.
2009
Wood CR, Reynolds DR, Wells PM, Barlow JF, Woiwod IP, Chapman JW (2009). Flight periodicity and the vertical distribution of high-altitude moth migration over southern Britain.
BULLETIN OF ENTOMOLOGICAL RESEARCH,
99(5), 525-535.
Author URL.
Chapman JW, Drake VA (2009). Insect Migration. In (Ed)
Encyclopedia of Animal Behavior, 161-166.
Abstract:
Insect Migration
Abstract.
Nesbit RL, Hill JK, Woiwod IP, Sivell D, Bensusan KJ, Chapman JW (2009). Seasonally adaptive migratory headings mediated by a sun compass in the painted lady butterfly, <i>Vanessa cardui</i>.
ANIMAL BEHAVIOUR,
78(5), 1119-1125.
Author URL.
2008
Reynolds DR, Smith AD, Chapman JW (2008). A radar study of emigratory flight and layer formation by insects at dawn over southern Britain.
BULLETIN OF ENTOMOLOGICAL RESEARCH,
98(1), 35-52.
Author URL.
Chapman JW, Reynolds DR, Hill JK, Sivell D, Smith AD, Woiwod IP (2008). A seasonal switch in compass orientation in a high-flying migrant moth.
Current Biology,
18(19).
Abstract:
A seasonal switch in compass orientation in a high-flying migrant moth
Most individual insect migrants have only a short time 'window' for migration (just a few nights) and comparatively slow airspeeds. Thus, to achieve long-range displacement into temporary breeding habitats, migrants must hitch a ride on fast-moving, high-altitude winds [1]. We recently demonstrated that the migratory noctuid moth Autographa gamma has evolved a compass mechanism which facilitates the successful return of autumn migrants from the United Kingdom to their winter ranges further south via the selection of favourable high-altitude winds [2]; this was the first convincing evidence of such a mechanism in insects that migrate predominantly at high altitudes. As pointed out in a commentary on that work [3], the question of whether or not a similar mechanism promotes northwards migration of such insects during the spring remained unanswered - we do not know if there is a reversal of the migrants' preferred compass orientation according to season. Here, studying A. gamma once again, we report the first evidence that a nocturnal migrant moth controls the direction of both its spring ('forward') and autumn ('return') high-altitude migrations, and that it also optimises its flight-altitude and compensates for cross-wind drift in a similar manner in both directions. © 2008 Elsevier Ltd. All rights reserved.
Abstract.
Chapman JW, Reynolds DR, Mouritsen H, Hill JK, Riley JR, Sivell D, Smith AD, Woiwod IP (2008). Wind Selection and Drift Compensation Optimize Migratory Pathways in a High-Flying Moth.
Current Biology,
18(7), 514-518.
Abstract:
Wind Selection and Drift Compensation Optimize Migratory Pathways in a High-Flying Moth
Numerous insect species undertake regular seasonal migrations in order to exploit temporary breeding habitats [1]. These migrations are often achieved by high-altitude windborne movement at night [2-6], facilitating rapid long-distance transport, but seemingly at the cost of frequent displacement in highly disadvantageous directions (the so-called "pied piper" phenomenon [7]). This has lead to uncertainty about the mechanisms migrant insects use to control their migratory directions [8, 9]. Here we show that, far from being at the mercy of the wind, nocturnal moths have unexpectedly complex behavioral mechanisms that guide their migratory flight paths in seasonally-favorable directions. Using entomological radar, we demonstrate that free-flying individuals of the migratory noctuid moth Autographa gamma actively select fast, high-altitude airstreams moving in a direction that is highly beneficial for their autumn migration. They also exhibit common orientation close to the downwind direction, thus maximizing the rectilinear distance traveled. Most unexpectedly, we find that when winds are not closely aligned with the moth's preferred heading (toward the SSW), they compensate for cross-wind drift, thus increasing the probability of reaching their overwintering range. We conclude that nocturnally migrating moths use a compass and an inherited preferred direction to optimize their migratory track. © 2008 Elsevier Ltd. All rights reserved.
Abstract.
2007
Chapman JW (2007). 29.1. Behavioural adaptations of long-range insect migrants. Comparative Biochemistry and Physiology Part a Molecular & Integrative Physiology, 148
Riley JR, Chapman JW, Reynolds DR, Smith AD (2007). Recent applications of radar to entomology.
Outlooks on Pest Management,
18(2), 62-68.
Abstract:
Recent applications of radar to entomology
This paper describes recent applications of vertical-looking radar to monitor migratory insect movements at high altitude, and of harmonic radar to record the flight paths of low-flying insects. Examples are given of how these radars have revealed novel information about the flight of bees, butterflies, moths and carabid beetles. The paper also briefly mentions some technical innovations designed to improve the performance of these radars. © 2007. Research Information Ltd. All rights reserved.
Abstract.
2006
Chapman JW, Reynolds DR, Brooks SJ, Smith AD, Woiwod IP (2006). Seasonal variation in the migration strategies of the green lacewing Chrysoperla carnea species complex.
Ecological Entomology,
31(4), 378-388.
Abstract:
Seasonal variation in the migration strategies of the green lacewing Chrysoperla carnea species complex
1. Insect migration strategies are generally poorly understood due to the propensity for high-altitude flight of many insect species, and the technical difficulties associated with observing these movements. While some progress has been made in the study of the migration of important insect pests, the migration strategies of insect natural enemies are often unknown. 2. Suction trapping, radar monitoring, and high-altitude aerial netting were used to characterise the seasonal migrations in the U.K. of an assemblage of aphid predators: three green lacewings in the Chrysoperla carnea species complex. 3. Chrysoperla carnea sens. str. was found to be very abundant at high altitudes during their summer migration, and some individuals were capable of migrating distances of ≈300 km during their pre-ovipositional period. In contrast, high-altitude flights were absent in the autumn migration period, probably due to a behavioural adaptation that increases the probability that migrants will encounter their over-wintering sites. The other two species in the complex, C. lucasina and C. pallida, were much rarer, making up ≈ 3% of the total airborne populations throughout the study period. 4. The summer migration of C. carnea sens. str. was not directly temporally associated with the summer migration of its cereal aphid prey, but lagged behind by about 4 weeks. There was also no evidence of spatial association between aphid and lacewing populations. 5. The results show that to understand the population ecology of highly mobile insect species, it is necessary to characterise fully all aspects of their migration behaviour, including the role of high-altitude flights. © 2006 the Authors.
Abstract.
Wood CR, Chapman JW, Reynolds DR, Barlow JF, Smith AD, Woiwod IP (2006). The influence of the atmospheric boundary layer on nocturnal layers of noctuids and other moths migrating over southern Britain.
International Journal of Biometeorology,
50(4), 193-204.
Abstract:
The influence of the atmospheric boundary layer on nocturnal layers of noctuids and other moths migrating over southern Britain
Insects migrating at high altitude over southern Britain have been continuously monitored by automatically operating, vertical-looking radars over a period of several years. During some occasions in the summer months, the migrants were observed to form well-defined layer concentrations, typically at heights of 200-400 m, in the stable night-time atmosphere. Under these conditions, insects are likely to have control over their vertical movements and are selecting flight heights that are favourable for long-range migration. We therefore investigated the factors influencing the formation of these insect layers by comparing radar measurements of the vertical distribution of insect density with meteorological profiles generated by the UK Meteorological Office's (UKMO) Unified Model (UM). Radar-derived measurements of mass and displacement speed, along with data from Rothamsted Insect Survey light traps, provided information on the identity of the migrants. We present here three case studies where noctuid and pyralid moths contributed substantially to the observed layers. The major meteorological factors influencing the layer concentrations appeared to be: (a) the altitude of the warmest air, (b) heights corresponding to temperature preferences or thresholds for sustained migration and (c) on nights when air temperatures are relatively high, wind-speed maxima associated with the nocturnal jet. Back trajectories indicated that layer duration may have been determined by the distance to the coast. Overall, the unique combination of meteorological data from the UM and insect data from entomological radar described here show considerable promise for systematic studies of high-altitude insect layering. © ISB 2006.
Abstract.
Reynolds DR, Chapman JW, Harrington R (2006). The migration of insect vectors of plant and animal viruses.
PLANT VIRUS EPIDEMIOLOGY,
67, 453-517.
Author URL.
2005
Chapman JW, Reynolds DR, Smith AD, Riley JR, Telfer MG, Woiwod IP (2005). Mass aerial migration in the carabid beetle Notiophilus biguttatus.
Ecological Entomology,
30(3), 264-272.
Abstract:
Mass aerial migration in the carabid beetle Notiophilus biguttatus
1. Catches in traps at 12 and 200 m above ground, and observations with entomological radar, were used to document the high-altitude windborne movements of carabid beetles over agricultural land in south-east U.K. during July 1999, 2000, 2002, and 2004. 2. Notiophilus biguttatus (Fabricius) was found to be the most abundant species at altitude, with flights by reproductively immature adults resulting in millions of beetles passing through a 1 km2 window during the brief migration period in July 2002. 3. This result was unexpected in view of the conclusions of an earlier, classic Dutch study by den Boer and colleagues that classified N. biguttatus as a poorly dispersing species that tended to become isolated in remnants of natural habitat. 4. Reasons for the discrepancy between the two studies are discussed. It is hypothesised that the high mobility seen in the N. biguttatus populations results from a recent adaptation of the beetle's migration syndrome allowing it to exploit the mosaic of temporary habitat patches making up the increasingly intensive agroecosystems of northern Europe. © 2005 the Royal Entomological Society.
Abstract.
Reynolds DR, Chapman JW, Edwards AS, Smith AD, Wood CR, Barlow JF, Woiwod IP (2005). Radar studies of the vertical distribution of insects migrating over southern Britain: the influence of temperature inversions on nocturnal layer concentrations.
Bulletin of Entomological Research,
95(3), 259-274.
Abstract:
Radar studies of the vertical distribution of insects migrating over southern Britain: the influence of temperature inversions on nocturnal layer concentrations
Insects migrating over two sites in southern UK (Malvern in Worcestershire, and Harpenden in Hertfordshire) have been monitored continuously with nutating vertical-looking radars (VLRs) equipped with powerful control and analysis software. These observations make possible, for the first time, a systematic investigation of the vertical distribution of insect aerial density in the atmosphere, over temporal scales ranging from the short (instantaneous vertical profiles updated every 15 min) to the very long (profiles aggregated over whole seasons or even years). In the present paper, an outline is given of some general features of insect stratification as revealed by the radars, followed by a description of occasions during warm nights in the summer months when intense insect layers developed. Some of these nocturnal layers were due to the insects flying preferentially at the top of strong surface temperature inversions, and in other cases, layering was associated with higher-altitude temperature maxima, such as those due to subsidence inversions. The layers were formed from insects of a great variety of sizes, but peaks in the mass distributions pointed to a preponderance of medium-sized noctuid moths on certain occasions. © CAB International, 2005.
Abstract.
2004
Chapman JW, Reynolds DR, Smith AD, Smith ET, Woiwod IP (2004). An aerial netting study of insects migrating at high altitude over England.
Bulletin of Entomological Research,
94(2), 123-136.
Abstract:
An aerial netting study of insects migrating at high altitude over England
Day and night sampling of windborne arthropods at a height of 200 m above ground was undertaken at Cardington, Bedfordshire, UK, during July 1999, 2000 and 2002, using a net supported by a tethered balloon. The results from this study are compared with those from the classic aerial sampling programmes carried out by Hardy, Freeman and colleagues over the UK and North Sea in the 1930s. In the present study, aerial netting was undertaken at night as well as daytime, and so the diel periodicity of migration could be investigated, and comparisons made with the results from Lewis and Taylor's extensive survey of flight periodicity near ground level. In some taxa with day-time emigration, quite large populations could continue in high-altitude flight after dark, perhaps to a previously underrated extent, and this would greatly increase their potential migratory range. Any trend towards increases in night temperatures, associated with global warming, would facilitate movements of this type in the UK. Observations on the windborne migration of a variety of species, particularly those of economic significance or of radar-detectable size, are briefly discussed.
Abstract.
Chapman JW, Reynolds DR, Smith AD (2004). Migratory and foraging movements in beneficial insects: a review of radar monitoring and tracking methods.
International Journal of Pest Management,
50(3), 225-232.
Abstract:
Migratory and foraging movements in beneficial insects: a review of radar monitoring and tracking methods
Knowledge of flight movement is crucial to an understanding of the ecology, behaviour, genetics and evolutionary success of most insect species. However, all but the shortest flights will frequently take the insect beyond the range of both human vision and many optoelectronic devices, and thus radar technology has a valuable role to play in several distinct areas of movement research. In this review, we firstly consider the monitoring of high-altitude windborne movements of insect natural enemies, with emphasis on how novel vertical-looking radars are being employed to observe the migrations of aphid predators in the UK. Secondly, we discuss how scanning radars, with and without harmonic tags, have increased our understanding of the foraging flights of beneficial pollinators (bees), and how this technique might be applied to natural enemies. Lastly, we outline the use of harmonic direction-finders in studying the pedestrian and short flight movements of various beneficial insects, including predators. In each case we highlight the strengths and limitations of the techniques, and the prospects for future advances. © 2004 Taylor and Francis Ltd.
Abstract.
2003
Penagos DI, Magallanes R, Valle J, Cisneros J, Martínez AM, Goulson D, Chapman JW, Caballero P, Cave RD, Williams T, et al (2003). Effect of weeds on insect pests of maize and their natural enemies in Southern Mexico.
International Journal of Pest Management,
49(2), 155-161.
Abstract:
Effect of weeds on insect pests of maize and their natural enemies in Southern Mexico
A pilot study performed on the Pacific coastal plain of Chiapas, Mexico, focused on the prevalence of maize crop infestation by insect pests, parasitism of pests and the abundance of insect predators in maize plots with weeds compared with plots under a regime of rigorous manual weed control. Sampling was conducted on four occasions at 20, 32, 44 and 56 days post-planting. Infestation of maize by fall armyworm larvae, Spodoptera frugiperda (Lepidoptera: Noctuidae), was more than twice as great in plots with strict weed control compared with weedy plots at 20 days post-planting, but declined thereafter in both treatments. The prevalence of aphid infestation and the abundance of nitidulid beetles were consistently greater in weed-controlled plots. In contrast, the density of beneficial predatory Coleoptera increased significantly in plots with weeds, and it is suggested that this probably explains the lower incidence of pests. S. frugiperda egg masses placed in experimental plots suffered a significantly higher incidence rate of parasitism by Chelonus insularis (Hymenoptera: Braconidae) in clean plots (42.0%) compared with those placed in weedy plots (3.75%); it is suspected that weeds may hinder the location of egg masses by parasitoids. Overall, the presence or absence of weeds had a marked influence on the arthropod community present in maize fields. The weeds did not affect maize plant height, the levels of plant damage or the yield of grain from plants under each type of weed regime, implying that competitive effects of weeds may be offset by greater numbers of beneficial insects in weedy plots. Our pilot study indicates that strict weed control in maize may be unnecessary.
Abstract.
Armenta R, Martínez AM, Chapman JW, Magallanes R, Goulson D, Caballero P, Cave RD, Cisneros J, Valle J, Castillejos V, et al (2003). Impact of a Nucleopolyhedrovirus Bioinsecticide and Selected Synthetic Insecticides on the Abundance of Insect Natural Enemies on Maize in Southern Mexico.
Journal of Economic Entomology,
96(3), 649-661.
Abstract:
Impact of a Nucleopolyhedrovirus Bioinsecticide and Selected Synthetic Insecticides on the Abundance of Insect Natural Enemies on Maize in Southern Mexico
The impact of commonly used organophosphate (chlorpyrifos, methamidophos), carbamate (carbaryl), and pyrethroid (cypermethrin) insecticides on insect natural enemies was compared with that of a nucleopolyhedrovirus (Baculoviridae) of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in maize grown in southern Mexico. Analyses of the SELECTV and Koppert Side Effects (IOBC) databases on the impact of synthetic insecticides on arthropod natural enemies were used to predict ≈75-90% natural enemy mortality after application, whereas the bioinsecticide was predicted to have no effect. Three field trails were performed in mid- and late-whorl stage maize planted during the growing season in Chiapas State, Mexico. Synthetic insecticides were applied at product label recommended rates using a manual knapsack sprayer fitted with a cone nozzle. The biological pesticide was applied at a rate of 3 x 1012 occlusion bodies (OBs)/ha using identical equipment. Pesticide impacts on arthropods on maize plants were quantified at intervals between 1 and 22 d postapplication. The biological insecticide based on S. frugiperda nucleopolyhedrovirus had no adverse effect on insect natural enemies or other nontarget insect populations. Applications of the carbamate, pyrethroid, and organophosphate insecticides all resulted in reduced abundance of insect natural enemies, but for a relatively short period (8-15 d). Pesticide applications made to late-whorl stage maize resulted in lesser reductions in natural enemy populations than applications made at the mid-whorl stage, probably because of a greater abundance of physical refuges and reduced spray penetration of late-whorl maize.
Abstract.
Chapman JW, Reynolds DR, Smith AD (2003). Vertical-looking radar: a new tool for monitoring high-altitude insect migration.
BioScience,
53(5), 503-511.
Abstract:
Vertical-looking radar: a new tool for monitoring high-altitude insect migration
Many insect species engage in high-altitude, wind-borne migration, often several hundred meters above the ground. At these heights they can use the wind to travel tens or-hundreds of kilometers in a single flight, and hence a knowledge of their movements is essential to understanding their ecology and population dynamics. Direct observation of high-flying insect migrants is very difficult, especially at night, but the remote sensing capabilities of entomological radar provide a solution to this seemingly intractable problem. We describe a novel, nutating-beam, vertical-looking radar with autonomous data analysis software. This system routinely extracts data on size, shape, alignment, and displacement vectors from individual targets, allowing long-term monitoring of migrant insect populations. We discuss the capabilities and limitations of this system and describe some of its applications in the study of insect migration behaviour.
Abstract.
2002
Chapman JW, Smith AD, Woiwod IP, Reynolds DR, Riley JR (2002). Development of vertical-looking radar technology for monitoring insect migration.
Computers and Electronics in Agriculture,
35(2-3), 95-110.
Abstract:
Development of vertical-looking radar technology for monitoring insect migration
The development of vertical-looking radar (VLR) has allowed long-term monitoring of the altitudinal and temporal dynamics of high-flying insect populations to be a practical proposition for the first time. The system also provides a unique insight into the behaviour of migrating insects. A new analysis routine for estimating body mass of over-flying insects is described. Procedures for calculating the maximum range of detection for insects of different sizes and the volume of air sensed by the VLR have also been developed. Sample data of diurnal patterns of activity, temporal variation of abundance and density-height profiles of aerial insect populations are presented. © 2002 Elsevier Science B.V. All rights reserved.
Abstract.
Chapman JW, Reynolds DR, Smith AD, Riley JR, Pedgley DE, Woiwod IP (2002). High-altitude migration of the diamondback moth Plutella xylostella to the U.K.: a study using radar, aerial netting, and ground trapping.
Ecological Entomology,
27(6), 641-650.
Abstract:
High-altitude migration of the diamondback moth Plutella xylostella to the U.K.: a study using radar, aerial netting, and ground trapping
1. The high-altitude wind-borne migration of the diamondback moth Plutella xylostella in the U.K. in 2000 was investigated (a) by direct monitoring of insect flight by vertical-looking radar and by aerial netting, and (b) through evidence of temporal variation in P. xylostella abundance deduced from a network of light traps. 2. Migrating P. xylostella were identified by a unique combination of size and shape data derived from the continuously operating vertical-looking radar. 3. Radar-detected migratory overflights correlated significantly with associated peaks in abundance of P. xylostella estimated by catches in a U.K.-wide light trap network; however the correlation was stronger when light trap catches were lagged by 1 day. 4. The first notable catches of P. xylostella in the U.K. occurred in early May, and were accompanied by migrations over the radar from the east. 5. Radar data and back-tracking indicated that a major wind-borne migration of P. xylostella from the Netherlands to southern England took place in early May, and that this was responsible for the establishment of the U.K. population. 6. The origin of early-season P. xylostella occurring in Britain is discussed.
Abstract.
2001
Escribano A, Williams T, Goulson D, Cave RD, Chapman JW, Caballero P (2001). Consequences of interspecific competition on the virulence and genetic composition of a nucleopolyhedrovirus in <i>Spodoptera frugiperda</i> larvae parasitized by <i>Chelonus insularis</i>.
BIOCONTROL SCIENCE AND TECHNOLOGY,
11(5), 649-662.
Author URL.
Goulson D, Chapman JW, Hughes WOH (2001). Discrimination of unrewarding flowers by bees; direct detection of rewards and use of repellent scent marks.
Journal of Insect Behavior,
14(5), 669-678.
Abstract:
Discrimination of unrewarding flowers by bees; direct detection of rewards and use of repellent scent marks
Bumblebees and honeybees deposit short-lived scent marks on flowers that they visit when foraging. Conspecifics use these marks to distinguish those flowers that have recently been emptied and, so, avoid them. The aim of this study was to assess how widespread this behavior is. Evidence for direct detection of reward levels was found in two bee species: Agapostemon nasutus was able to detect directly pollen availability in flowers with exposed anthers, while Apis mellifera appeared to be able to detect nectar levels of tubular flowers. A third species, Trigona fulviventris, avoided flowers that had recently been visited by conspecifies, regardless of reward levels, probably by using scent marks. Three further bee/flower systems were examined in which there was no detectable discrimination among flowers. We argue that bees probably rely on direct detection of rewards where this is allowed by the structure of the flower and on scent marks when feeding on flowers where the rewards are hidden. However, discrimination does not always occur. We suggest that discrimination may not always make economic sense; when visiting flowers with a low handling time, or fiowers that are scarce, it may be more efficient to visit every flower that is encountered.
Abstract.
2000
Chapman JW, Williams T, Martínez AM, Cisneros J, Caballero P, Cave RD, Goulson D (2000). Does cannibalism in Spodoptera frugiperda (Lepidoptera: Noctuidae) reduce the risk of predation?.
Behavioral Ecology and Sociobiology,
48(4), 321-327.
Abstract:
Does cannibalism in Spodoptera frugiperda (Lepidoptera: Noctuidae) reduce the risk of predation?
The incidence of cannibalism of larval Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize under field conditions was investigated using field cages. Cannibalism was found to account for approximately 40% mortality when maize plants were infested with two or four fourth-instar larvae over a 3-day period. Field trials examined the effect of larval density on the prevalence of natural enemies of S. frugiperda. The abundance of predators (earwigs, staphylinids, other predatory beetles, and Chrysoperla spp.) was significantly greater on maize plants with higher levels of larval feeding damage, while the relationship between predator abundance and number of S. frugiperda larvae per plant was less clear. As larval damage is probably a more reliable indicator of previous larval density than numbers collected at an evaluation, this indicates that predation risk will be greater for larvae living in large groups. Parasitism accounted for 7.1% mortality of larvae in sorghum, and involved six species of Hymenoptera and Tachinidae. There was no effect of larval density or within-plant distribution on the probability of larval attack by parasitoids. The selective benefits of cannibalism, in relation to the risk of predation and parasitism, are discussed.
Abstract.
Escribano A, Williams T, Goulson D, Cave Ronald D, Chapman Jason W, Caballero P (2000). Effect of parasitism on a nucleopolyhedrovirus amplified in Spodoptera frugiperda larvae parasitized by Campoletis sonorensis.
Entomologia Experimentalis et Applicata,
97(3), 257-264.
Abstract:
Effect of parasitism on a nucleopolyhedrovirus amplified in Spodoptera frugiperda larvae parasitized by Campoletis sonorensis
We evaluated the consequences of parasitism by the solitary ichneumonid endoparasitoid Campoletis sonorensis (Cameron) towards the replication, genetic composition and virulence of a nucleopolyhedrovirus (Baculoviridae) originating from Spodoptera frugiperda (J. E. Smith) larvae. Parasitism by C. sonorensis and viral infection of third and fourth instar S. frugiperda larvae resulted in reduced growth compared with nonparasitized control larvae. A positive correlation was observed between virus yield and larval instar at the moment of infection. When larvae were virus-inoculated in the fourth instar, parasitism resulted in a significant reduction in mean per capita virus yield compared to the virus yield from nonparasitized larvae. In an experiment involving 10 serial passages of virus in both parasitized and nonparasitized larvae, restriction endonuclease analysis of viral DNA amplified in nonparasitized larvae revealed the presence of the wild-type virus as well as three additional variants (A, B, and C) diagnosed by the presence of novel submolar PstI fragments of different sizes. In contrast, analysis of viral DNA from parasitized larvae showed the presence of the wild-type virus and two other variants (E and F), each characterized by a different submolar BglII fragment. Southern blot analysis indicated that the submolar fragments of variants E and F contained sequences originating from the viral genome. Bioassay of the different virus variants in S. frugiperda larvae indicated that their virulence was equal or less than that of the wild-type virus. We conclude that parasitism can affect the quantity of virus produced in dually infected and parasitized larvae, but no adverse effects were detected in terms of the biological activity of the virus.
Abstract.
Chapman JW, Goulson D (2000). Environmental versus genetic influences on fluctuating asymmetry in the house fly, <i>Musca domestica</i>.
BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY,
70(3), 403-413.
Author URL.
CHAPMAN J (2000). Environmental versus genetic influences on fluctuating asymmetry in the house fly, Musca domestica. Biological Journal of the Linnean Society, 70(3), 403-413.
Chapman JW, Goulson D (2000). Environmental versus genetic influences on fluctuating asymmetry in the house fly, Musca domestica.
Biological Journal of the Linnean Society,
70(3), 403-413.
Abstract:
Environmental versus genetic influences on fluctuating asymmetry in the house fly, Musca domestica
The causes of fluctuating asymmetry (FA) are poorly understood, yet it has been widely used as a measure of fitness. Many studies have demonstrated that individuals with low FA are preferred as mates, and it has been argued that this is because FA provides an indicator of genetic quality. However, the relative importance of genes versus environment in determining the level of FA shown by an organism is currently the subject of much controversy. As yet there is no clear consensus as to whether FA generally has a heritable component and if so how large this might be, or indeed if it is sensible to generalize at all. In Musca domestica flies with low wing length FA have beeen found to enjoy higher mating success. In order to interpret this finding we assess whether wing length FA in this species is heritable, and also how it is influenced by environmental stresses induced by temperature and crowding. We also examine whether offspring viability is related to parental FA. We found that wing length FA in M. domestica had no detectable heritable components, and parental FA did not influence offspring viability. FA was influenced by rearing temperature, with flies exhibiting highest FA at the lowest rearing temperature (15°C). Larval survival rate was greatest, and the resulting adults largest, at the intermediate rearing temperature (25°C) compared to higher or lower temperatures, suggesting that 25°C is close to the optimum for the development of M. domestica. Adult size appears to provide a better indicator of stress during development than does wing FA. These results are discussed in relation to the utility of FA as a tool for use in evolutionary studies. (C) 2000 the Linnean Society of London.
Abstract.
Martínez AM, Goulson D, Chapman JW, Caballero P, Cave RD, Williams T (2000). Is it feasible to use optical brightener technology with a baculovirus bioinsecticide for resource-poor maize farmers in mesoamerica?.
Biological Control,
17(2), 174-181.
Abstract:
Is it feasible to use optical brightener technology with a baculovirus bioinsecticide for resource-poor maize farmers in mesoamerica?
Stilbene-derived optical brighteners greatly enhance the infectivity of a number of baculoviruses. This technology has been patented for use with insect pathogenic viruses in the United States and Canada. A baculovirus is currently being tested for its potential as a biological insecticide of Spodoptera frugiperda (Lepidoptera: Noctuidae), the principal insect pest of maize in Mesoamerica. A multiply embedded nucleopolyhedrovirus isolate originally from Nicaragua was bioassayed alone and in the presence of the optical brightener Tinopal LPW (1%), using second instar S. frugiperda larvae. The LC50 value of the virus alone was calculated at 82.1 polyhedral inclusion bodies (PIBs)/mm2 of diet compared with 0.71 PIBs/mm2 in the presence of Tinopal LPW. In contrast to other studies, the mean time to death of larvae exposed to virus and Tinopal LPW was significantly extended compared to larvae inoculated with virus alone. Analysis of the results of eight independent field trials in Mexico and Honduras revealed a significant positive relationship between log virus dose and percentage mortality observed in S. frugiperda larvae. Virus-induced mortality was approximately 50% at the highest application rate tested: 1000 larval equivalents (LE) of virus/ha. When the impact of parasitism was taken into account, larval mortality increased to 45.0-90.7% in plots treated with virus at 250 LE/ha or more. A cost analysis indicated that approximately 60% pest control can be achieved as a conservative estimate with virus application and the action of parasitoids for the price of a chemical insecticide. Formulating the virus with an optical brightener appears to be an attractive option based on laboratory findings but requires field testing. The use of optical brightener technology will probably be feasible for maize growers in Mesoamerica only if it is highly effective at very low concentrations (
Abstract.
1999
Chapman JW, Williams T, Escribano A, Caballero P, Cave RD, Goulson D (1999). Age-related cannibalism and horizontal transmission of a nuclear polyhedrosis virus in larval Spodoptera frugiperda.
Ecological Entomology,
24(3), 268-275.
Abstract:
Age-related cannibalism and horizontal transmission of a nuclear polyhedrosis virus in larval Spodoptera frugiperda
1. Experiments were carried out to investigate the incidence of cannibalism throughout the larval development of the noctuid moth Spodoptera frugiperda, and to examine the risk of infection from consuming conspecifics infected with a nuclear polyhedrosis virus (SfNPV). 2. Cannibalism was observed commonly even when food was not limiting, but occurred more frequently at low food quantities and/or high rearing densities. The sex of the larvae had no effect on the incidence of cannibalistic behaviour, however the probability of cannibalism occurring was affected by larval stage. The frequency of cannibalism was significantly higher among fifth- and sixth-instar larvae than among earlier instars, and larvae were more likely to consume younger conspecifics than larvae of the same stage. 3. Fifth-instar larvae offered fourth-instar victims fed equally on healthy larvae, virus-infected larvae (2 days post-infection), uninfected corpses, and virus-killed corpses (6 days post-infection). Horizontal transmission of SfNPV was only recorded in larvae offered virus-killed corpses, however, and total mortality in this treatment was only 32%. 4. In a similar experiment, fourth-instar larvae avoided cannibalising virus-killed corpses. Horizontal transmission of SfNPV was recorded in fourth-instar larvae that consumed 2-day post-infected larvae. The low incidence of cannibalism observed in fourth-instar larvae, however, suggests that this is unlikely to provide an important route for the transmission of SfNPV.
Abstract.
Williams T, Goulson D, Caballero P, Cisneros J, Martínez AM, Chapman JW, Roman DX, Cave RD (1999). Evaluation of a baculovirus bioinsecticide for small-scale maize growers in Latin America.
Biological Control,
14(2), 67-75.
Abstract:
Evaluation of a baculovirus bioinsecticide for small-scale maize growers in Latin America
Near identical trials conducted concurrently in maize plots in Honduras and Mexico produced similar results in the pattern of larval mortality of Spodoptera frugiperda following application of a baculovirus or a conventional synthetic insecticide. The highest application rates of virus resulted in approximately 40% mortality of S. frugiperda larvae. Virus-induced mortality decreased with time. Parasitism by wasps and tachinids also contributed up to 40% mortality in field-collected larvae. The application of chlorpyrifos resulted in a resurgence of S. frugiperda. Chlorpyrifos also reduced a number of important predators in the maize crop which is likely to have been influential in the observed resurgence of this pest. The use of granulated sugar in the viral formulation caused an increase in the population density of several maize-associated insect species, and in Mexico a transient increase in parasitism was observed in sugar-treated plots. Sugar did not appear to increase the probability of infection by acting as a feeding stimulant in either trial. A preliminary analysis of the cost of vital production and application indicates that virus was considerably more costly than conventional control. To be commercially viable, economies of scale both in the cost of raw material for the insect diet and in the efficiency of manpower-related activities are needed to substantially reduce the costs of the viral product. Despite high levels of infestation by S. frugiperda, grain weight/cob was not significantly improved by the application of the biological or synthetic insecticide. Natural mortality factors both biotic and abiotic appear to have a large impact on larval S. frugiperda populations. For improvements in yield, the impact of control measures against S. frugiperda may be dependent on plant growth stage. Trials on timing and frequency of virus application are in progress to test this idea.
Abstract.
Chapman JW, Williams T, Escribano A, Caballero P, Cave RD, Goulson D (1999). Fitness consequences of cannibalism in the fall armyworm, Spodoptera frugiperda.
Behavioral Ecology,
10(3), 298-303.
Abstract:
Fitness consequences of cannibalism in the fall armyworm, Spodoptera frugiperda
We investigated the consequences of cannibalism for some correlates of fitness in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae). The benefits gained by cannibals were ascertained by comparing survival, development rate, and pupal weight of larvae that had the opportunity to cannibalize with those that did not, at two levels of food availability. Larvae in the cannibalism treatments were provided with a conspecific one instar younger than themselves on five dates throughout larval development. Cannibalism was frequent; given the opportunity all larvae predated at least one younger conspecific. The frequency of cannibalism was not affected by the sex of the cannibal or by the availability of alternative food. However, cannibals suffered a significant reduction in survival at both high and low food availability. Furthermore, cannibals had a lower pupal weight in the high food treatment and a reduced development rate in the low food treatment. The only detectable fitness benefit associated with cannibalism was a positive correlation between the number of victims consumed and development rate under conditions of low food availability. On balance, cannibalism appears to be costly; alternative explanations for its occurrence in this species are discussed.
Abstract.
Goulson D, Hughes WOH, Chapman JW (1999). Fly populations associated with landfill and composting sites used for household refuse disposal.
Bulletin of Entomological Research,
89(6), 493-498.
Abstract:
Fly populations associated with landfill and composting sites used for household refuse disposal
Calyptrate fly populations were monitored with sticky traps at the following sites in Hampshire, UK during August to November 1998: a landfill and composting site (Paulsgrove), a site adjacent to this landfill (Port Solent), a site with no landfill nearby (Gosport), and a composting site with no landfill nearby. Overall, house flies Musca domestica (Linnaeus) and lesser house flies Fannia spp. were not important constituents of the dipteran catch, while bluebottles (Calliphora spp.) and greenbottles (Lucilia spp.) comprised approximately 12% of the total. Very large fly populations were found at the two composting sites, and it seems likely that these provide ideal breeding grounds for a range of fly species since they offer an abundance of warm decaying organic matter. Large fly populations were also evident at the landfill site. The suitability of household waste for the development of calyptrate Diptera was confirmed in a controlled trial: a mean of 0.43 adults emerged per kilo of one-week-old waste. Since many hundreds of tonnes of waste are delivered to the landfill daily, it is clear that the landfill is likely to substantially increase the local population of calyptrate flies. However, the data suggest that there was little movement of Diptera from the landfill to Port Solent situated approximately 500 m away. The most important calyptrate flies at this site were the cluster flies Pollenia rudis (Fabricius) and P. amentaria (Scopoli); the landfill site is unlikely to provide a suitable breeding site for these flies, as the larvae develop as parasites of earthworms. Significantly more flies emerged from one-week-old than from two-week-old household waste. A comparison of different barriers to the emergence of adult house flies from waste demonstrated that sacking provided an effective barrier to fly emergence, but that soil did not differ significantly from control treatments. If managed appropriately, it seems that the use of sacking over landfill waste could substantially reduce associated fly populations.
Abstract.
Escribano A, Williams T, Goulson D, Cave RD, Chapman JW, Caballero P (1999). Selection of a nucleopolyhedrovirus for control of Spodoptera frugiperda (Lepidoptera: Noctuidae): Structural, genetic, and biological comparison of four isolates from the Americas.
Journal of Economic Entomology,
92(5), 1079-1085.
Abstract:
Selection of a nucleopolyhedrovirus for control of Spodoptera frugiperda (Lepidoptera: Noctuidae): Structural, genetic, and biological comparison of four isolates from the Americas
Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is the principal pest of maize in tropical and subtropical regions of the Americas. Larvae of this species are susceptible to a nucleopolyhedrovirus (NPV) which has attracted interest as a potential biocontrol agent. Four strains of NPV isolated from infected S. frugiperda larvae in the United States, Nicaragua, and Argentina were subjected to a structural, genetic, and biological comparison to select a candidate isolate for use in biocontrol experiments in Mexico and Honduras. All isolates had an occlusion body polyhedrin protein of 32 kDa, but the virions of each isolate differed subtly in the pattern and abundance of certain structural polypeptides revealed by SDS-PAGE analysis. Restriction endonuclease analysis of viral DNA confirmed that these isolates were strains of a single virus species but showed that they were not genetically homogeneous; each isolate could be differentiated from the others using common restriction enzymes. Droplet feeding bioassays indicated that an isolate from Nicaragua (Sf-NIC) and an isolate from the United States (Sf-US) had the highest infectivity when tested against 2nd instars originating from a Honduran S. frugiperda colony. No significant differences were detected in the speed of kill of Sf-NIC (102.7 h), Sf-US (102.3 h), and Sf-AR (103.4h), whereas that of Sf-2 (97.3 h) was significantly shorter. Additional bioassays of the Sf-NIC isolate against 2nd to 6th instars demonstrated that LC50 values increased with larval stage from 2.03x 105 OBs/ml for 2nd instars to 1.84 x 108 OBs/ml for 5th instars. The concentration required to elicit a lethal infection of 6th instars was so high that a reliable estimate of LC50 could not be obtained. The mean time to death for each stage challenged with the Sf-NIC isolate increased with instar from an average of 102.7 h in 2nd instars to 136.9 h in 5th instars.
Abstract.
Goulson D, Bristow L, Elderfield E, Brinklow K, Parry-Jones B, Chapman JW (1999). Size, symmetry, and sexual selection in the housefly, Musca domestica.
Evolution,
53(2), 527-534.
Abstract:
Size, symmetry, and sexual selection in the housefly, Musca domestica
Relationships between measures of body size, asymmetry, courtship effort, and mating success were investigated in the housefly, Musca domestica (Diptera: Muscidae). A previous study indicated that both male and female flies with low fluctuating asymmetry enjoyed enhanced mating success. The aim of our investigations was to determine whether the greater success of symmetrical males is due to variation in male mating effort or to female choice and whether males exhibited mate choice. However, our study found directional rather than fluctuating asymmetry, with both male and female flies having, on average, longer left wings than right. Also, asymmetry was not related to mating success in either sex. Rather, both males and females appeared to exhibit choice on the basis of the size of potential mates, with males preferring females with long bodies and females preferring heavy males. Possible benefits from choice of large mates are discussed. The initial mating strikes (in which the male leaps onto the back of the female) did not appear to be targeted according to female morphology, and their frequency did not vary according to male morphology. This indicates that mate choice by both sexes according to size probably occurs during the later stages of courtship, when the flies are in intimate contact. Possible reasons for the absence of choice according to asymmetry are discussed.
Abstract.
Chapman JW, Knapp JJ, Goulson D (1999). Visual responses of Musca domestica to pheromone impregnated targets in poultry units.
Med Vet Entomol,
13(2), 132-138.
Abstract:
Visual responses of Musca domestica to pheromone impregnated targets in poultry units.
Field trials investigating the effect of visual cues on catches of Musca domestica (Diptera: Muscidae) at toxic targets impregnated with the female sex pheromone (Z)-9-tricosene, were conducted in a caged-layer deep-pit poultry unit in southern England. Targets treated with azamethiphos and baited with 2.5 g of 40% (Z)-9-tricosene impregnated beads caught significantly greater numbers of M. domestica than control targets. The greater attractiveness of the pheromone impregnated targets persisted for at least 5 weeks. The addition of longitudinal black stripes, or a regularly spaced pattern of black spots, to the white targets had no effect on catch rates. However, a pattern of clustered black spots, designed to imitate groups of feeding M. domestica, significantly increased target catches; this effect was particularly pronounced in the targets impregnated with (Z)-9-tricosene. Trials comparing the attractiveness of white and fluorescent yellow pheromone-treated targets under two different lighting regimes indicated that M. domestica does not have a significant preference for either colour. The implications of these results in relation to the control of M. domestica populations in poultry units are discussed.
Abstract.
Author URL.
1998
Chapman JW, Knapp JJ, Howse PE, Goulson D (1998). An evaluation of (<i>Z</i>)-9-tricosene and food odours for attracting house flies, <i>Musca domestica</i>, to baited targets in deep-pit poultry units.
ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA,
89(2), 183-192.
Author URL.
Chapman JW, Knapp JJ, Howse PE, Goulson D (1998). An evaluation of (Z)-9-tricosene and food odours for attracting house flies, Musca domestica, to baited targets in deep-pit poultry units.
Entomologia Experimentalis et Applicata,
89(2), 183-192.
Abstract:
An evaluation of (Z)-9-tricosene and food odours for attracting house flies, Musca domestica, to baited targets in deep-pit poultry units
Field trials investigating the effect of food baits on catches of Musca domestica at toxic targets impregnated with the female sex pheromone, (Z)-9-tricosene, were conducted in a caged-layer deep-pit poultry unit in southern England. Targets treated with an Alfacron-sugar mixture and baited with 2.5 g of 40% (Z)-9-tricosene beads caught significantly greater numbers of both male and female M. domestica than control targets. Egg and milk-baited targets were less attractive than controls, while brewers yeast slightly increased the numbers of M. domestica attracted. However, the inclusion of brewers yeast in (Z)-9-tricosene-impregnated targets produced a significant reduction in the number of male M. domestica attracted. Increased female attraction was elicited by baiting the targets with 2-phenylethanol, at the quantities of 1 mg and 10 mg. However, 2-phenylethanol had no effect on female attraction when presented in conjunction with (Z)-9-tricosene. The implications of these results in relation to the control of M. domestica populations in poultry units are discussed.
Abstract.
Chapman JW, Howse PE, Knapp JJ, Goulson D (1998). Evaluation of three (Z)-9-tricosene formulations for control of Musca domestica (Diptera: Muscidae) in caged-layer poultry units.
J Econ Entomol,
91(4), 915-922.
Abstract:
Evaluation of three (Z)-9-tricosene formulations for control of Musca domestica (Diptera: Muscidae) in caged-layer poultry units.
A field trial comparing the effectiveness of toxic targets impregnated with different formulations of the Musca domestica L. female sex pheromone (Z)-9-tricosene was conducted in a caged-layer, deep-pit poultry unit in southern England. Targets baited with 5 g of technical grade (Z)-9-tricosene, or 5 g of a 40% polymer bead formulation, caught significantly greater numbers of M. domestica than control targets. This increase in attractiveness of the pheromone-impregnated targets persisted for at least 24 wk. However, mean daily catch rates of M. domestica at targets baited with 5 g of a 2% wettable powder formulation did not significantly differ from control levels. Technical grade and bead formulations of the pheromone attracted significantly more males than females. However, the catches of female M. domestica at these pheromone-impregnated targets were significantly greater than female catches at control targets. Monitoring with sticky cards indicated that the introduction of toxic targets successfully suppressed adult M. domestica population density for up to 13 wk. Possible hypotheses explaining the effect of (Z)-9-tricosene on female attraction are discussed.
Abstract.
Author URL.
