Variation In Foraging Behavior Research Articles

Does intraspecific variation in Trissolcus japonicus affect its response to non-target hosts?

AbstractHost specificity is a key criterion for the implementation of any biological control program. In parasitoid wasps, host specificity is mediated by their response to chemical cues directly and indirectly associated with their hosts during foraging. Although intraspecific variation in foraging behaviour is documented, it is rarely integrated into risk assessment studies of potential biological control agents, as is the case for Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), an Asian egg parasitoid and biological control agent of the invasive Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). In the present study, we compared the behavioural response of T. japonicus females of an adventive line present in Switzerland and an Asian line (Beijing USDA), recently mass released in Italy, to cues of its target host H. halys and non-target host Pentatoma rufipes (L.) (Hemiptera: Pentatomidae). We observed minimal differences in host acceptance, exploitation and suitability in no-choice tests. In contrast, the behavioural response to host contact kairomones left on leaf substrates significantly differed between the two lines. While both lines preferred chemical footprints of H. halys in comparison to P. rufipes, females of the Beijing USDA line responded more strongly to host kairomones. The observed intraspecific variation in behavioural traits highlights the relevance of considering genetically distinct parasitoid lines and their host foraging behaviour in biological risk assessment studies. However, the implications of intraspecific variation in parasitoid foraging behaviour for biological control of a pest and non-target effects in the field remain challenging to predict.

Variability in at-sea foraging behaviour of little penguins Eudyptula minor in response to finescale environmental features

A long-standing question in ecology is how predators interact with their environment when locating patchily distributed prey. There is some evidence to suggest that marine predators use environmental features as foraging cues at meso-scales (100-1000 km); however, the role of environmental structure at finer scales (1-100 km) is less well understood. To investigate how marine predators respond to fine-scale environmental variability, the movement patterns of 29 GPS-tagged little penguins Eudyptula minor from 3 colonies in the highly variable Storm Bay ecosystem in south-eastern Tasmania, Australia, were analysed using hidden Markov behavioural state modelling alongside high-resolution environmental data. Variability in at-sea behavioural states was observed between colonies correlating with differences in fine-scale environmental parameters. There were significant differences in trip metrics and time spent in each of the identified behavioural states between each of the study colonies. Additionally, transitions between behavioural states were associated with different environmental parameters at each site. This variability in foraging behaviour for conspecifics at similar temporal scales illustrates the significance of fine-scale environmental variability in determining at-sea predator behaviour and highlights how even subtle differences in fine-scale environmental parameters can lead to alternative foraging strategies. This flexibility suggests a capacity to behaviourally adapt to variable and changing environmental conditions, a necessary condition for persistence in a changing world.

Genetic Architecture of Natural Variation Underlying Adult Foraging Behavior That Is Essential for Survival of Drosophila melanogaster

Foraging behavior is critical for the fitness of individuals. However, the genetic basis of variation in foraging behavior and the evolutionary forces underlying such natural variation have rarely been investigated. We developed a systematic approach to assay the variation in survival rate in a foraging environment for adult flies derived from a wild Drosophila melanogaster population. Despite being such an essential trait, there is substantial variation of foraging behavior among D. melanogaster strains. Importantly, we provided the first evaluation of the potential caveats of using inbred Drosophila strains to perform genome-wide association studies on life-history traits, and concluded that inbreeding depression is unlikely a major contributor for the observed large variation in adult foraging behavior. We found that adult foraging behavior has a strong genetic component and, unlike larval foraging behavior, depends on multiple loci. Identified candidate genes are enriched in those with high expression in adult heads and, demonstrated by expression knock down assay, are involved in maintaining normal functions of the nervous system. Our study not only identified candidate genes for foraging behavior that is relevant to individual fitness, but also shed light on the initial stage underlying the evolution of the behavior.

Individualistic herds: Individual variation in herbivore foraging behavior and application to rangeland management

Rangeland systems cover vast areas of the earth's surface containing great diversity of life, and contribute to the livelihoods and welfare of millions of people. The management of rangeland systems for ecological and commercial outcomes is driven by a need to understand how grazing animals achieve most efficient and sustainable use of resources within the landscape. This process is multi-faceted; however, advances in understanding how foraging animals form decisions in complex landscapes offers strong potential for enabling rangeland managers to predict, and manage, the grazing distribution of large herbivores. Recently, there have been increasing calls to incorporate variation in individual behavior to enhance management of grazing distributions across resources or landscapes. However, widespread adoption of this approach has not occurred. Here, we review the roles of morphology, physiology, experience, and environmental and social conditions in driving differences in individual foraging behavior in large herbivores, and how these individual differences can be maintained within wild populations. We then synthesise this knowledge to examine if viable opportunities for exploiting individual differences in the behavior of livestock exist. We conclude by identifying remaining important challenges and areas for future research to facilitate using individual variation in foraging behavior to manage grazing patterns in rangeland systems.