Jason W. Chapman
University of Exeter
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Featured researches published by Jason W. Chapman.
Science | 2010
Jason W. Chapman; Rebecca L. Nesbit; Laura Burgin; Don R. Reynolds; Alan D. Smith; Douglas R. Middleton; Jane K. Hill
Not at the Mercy of the Wind How can insects that migrate at high altitudes on fast-moving winds influence their direction of migration, when wind speeds typically exceed their self-propelled air speeds by a factor of three or four? Using automated vertical-looking entomological radar systems, Chapman et al. (p. 682) show that compass-mediated selection of favorable tailwinds, and partial correction for crosswind drift, are widespread phenomena in migrant insect species. Specialized flight behaviors have decisive influence on the migration pathways achieved by insects. Thus, contrary to popular belief, migrant insects are not at the mercy of the wind. Radar reveals that insects use high-altitude winds and correct for crosswind drift during long-range migrations. 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.
Annual Review of Entomology | 2011
Jason W. Chapman; V. Alistair Drake; Don R. Reynolds
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 influencing 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.
Ecological Entomology | 2002
Jason W. Chapman; Don R. Reynolds; Alan D. Smith; J. R. Riley; David E. Pedgley; Ian P. Woiwod
Abstract 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.
BioScience | 2003
Jason W. Chapman; Don R. Reynolds; Alan D. Smith
Abstract 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.
Journal of Insect Behavior | 2001
Dave Goulson; Jason W. Chapman; William O. H. Hughes
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 flowers that are scarce, it may be more efficient to visit every flower that is encountered.
Bulletin of Entomological Research | 2004
Jason W. Chapman; Don R. Reynolds; Alan D. Smith; E.T. Smith; Ian P. Woiwod
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 Taylors 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.
Royal Society of London. Proceedings B. Biological Sciences; 278, pp 3074-3080 (2011) | 2011
Thomas Alerstam; Jason W. Chapman; Johan Bäckman; Alan D. Smith; Håkan Karlsson; Cecilia Nilsson; Don R. Reynolds; Raymond H. G. Klaassen; Jane K. Hill
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.
Proceedings of the National Academy of Sciences of the United States of America | 2012
Jason W. Chapman; James R. Bell; Laura Burgin; Don R. Reynolds; Lars Pettersson; Jane K. Hill; Michael B. Bonsall; Jeremy A. Thomas
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.
Ecological Entomology | 1999
Jason W. Chapman; Trevor Williams; Ana Escribano; Primitivo Caballero; Ronald D. Cave; Dave Goulson
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).
Behavioral Ecology and Sociobiology | 2000
Jason W. Chapman; Trevor Williams; Ana-Mabel Martínez; Juan Cisneros; Primitivo Caballero; Ronald D. Cave; Dave Goulson
Abstract 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.