Research

I investigate how insects integrate behavior and physiology to cope with both natural and anthropogenic stressors including the destruction of their habitats and fragmentation, the risk of predation, and limited available nutrients.

1. Insect responses to landscape fragmentation

Habitat loss and fragmentation are a common consequence of modern agricultural practices and urbanization.  To persist, organisms must adjust their behavior and physiology in response to the biotic and abiotic challenges that result from the modification of their habitats. I investigate how landscape fragmentation translates into changes in organisms’ function by addressing two challenges:           

Challenge 1.  Disentangling direct and indirect  effects  offragmentation (Fig. 1).

Challenge 2. Linking processes across scales: Landscape characteristics→   Microhabitat →    Organism

Fig. 1 Landscape fragmentation may affect insect function directly (e.g. increased patch isolation), but also indirectly, by changing microclimate and presence of natural enemies.

 

2. Stress responses to predation risk

Like all phenotypes, antipredator responses may be determined by direct genetic effects (inherited genes), environmental conditions, and maternal effects. Using the Colorado potato beetle (Leptinotarsa decemlineata), a major pest of potato crops I study (Fig. 2):

  • Prey responses withing and across generations: For example, I have found that predator-induced maternal effects, by promoting intraclutch cannibalism, can improve offspring responses to the risk of predation:
  •  Stress responses to predation risk: Offspring behavioral and physiological responses  may function as alternative adaptive mechanisms of predator avoidance. While cannibals responded behaviorally to predation risk, non-cannibals relied more heavily on their physiological responses: increasing metabolic rate and usage of lipids

Fig. 2. (a) Podisus maculiventris predator attacking L. decemlineata larva while foraging. (b) Newly hatched larva cannibalizing an egg sibling. (c) Graph shows how prey nutritional condition, via cannibalism, differentially affects the behavioral and physiological responses to predation risk.

3. Nutrient limitation and dynamic allocation trade-offs

The nutrients that organisms need to support their many structures and physiological functions are often in limited supply, leading to resource allocation tradeoffs. The potential tradeoff between flight and fecundity has attracted much interest from insect biologists. Yet, previous studies of flight-fecundity tradeoff physiology have provided only a snapshot of the life of the organism, which may lead to both over and under estimation of the impacts of the tradeoff.

As part of a recently funded NSF IOS grant, in collaboration with Goggy Davidowitz, I am studying how the acquisition and allocation of nutritional resources, at different points in life, modulate flight-fecundity tradeoffs in Pieris rapae butterflies  (Fig. 3). In this project we integrate approaches from nutritional ecology with cutting-edge stable isotope tracer methodologies to identify the sources and biochemical fates of specific nutrients literally second by second, throughout the full life cycle of an individual and across generations.

Fig. 3 Theoretical representation of how multiple resource pools (yellow boxes), and different resource currencies (purple dashed lines- slopes are illustrative) modulate flight-fecundity tradeoffs in P. rapae butterflies. Acquisition and allocation of resources can be independent of one another (straight arrows). At the same time, allocation to flight vs. fecundity may affect a female ability to acquire further resources (circular arrow).

Nutrition and trade-offs in a herbivore-pollinator system: A second aspect of this project will be to determine how nutrition in the herbivorous larva affects the adult pollinator. While P. rapae larvae are avid consumers of leaf tissue, as adults, they feed on nectar and play a major role as pollinators in both natural and urban ecosystems. This research will help us to understand how nutrition during the larval stage and flight-fecundity tradeoffs change the adult nectar preferences and flower visitation rates, and thus may impact P. rapae performance as a pollinator.