UC Davis

The study of insect behavior in agroecosystems offers opportunities to understand fundamental concepts in behavioral ecology and to improve the management of pests for the sake of agricultural production. The following dissertation is a series of papers focused on insect pest behavior and trait-mediated effects. Chapter 1 is a synthetic review paper that develops a framework for utilizing the large body of literature on enemy-risk effects to improve arthropod pest management. While the field of biological control of pests is built on natural enemy ecology, insights gleaned from the study of enemy-risk effects have not been fully incorporated into biological control practice. This paper provides an overview of key concepts from both fields, reviews the literature where they intersect, and provides both conceptual discussions and case studies of particularly relevant applications. Chapter 2 is a paper modeling the collective movement behavior of a devastating pest, the Australian plague locust, using combined agent- based and partial differential equation models. While many models of locust movement rely on interactions between individuals, we demonstrate that foraging behavior generates the characteristic traveling wave pattern of Australian plague locust hopper bands. Finally, Chapter 3 is a manuscript investigating an agent-based model of the population and disease dynamics of a system where infection induces cannibalistic behavior. This study was inspired in part by the case of Geocoris pallens, a common beneficial insect in agricultural systems, whose California populations have suffered from increased cannibalism in the face of a novel pathogen. While only empirically documented in a few systems, disease often induces energetic stress, a key trigger of cannibalistic behavior, which is widespread among animal taxa. I present the results of a series of in silico experiments investigating the interacting effects of pathogenic virulence and pathogen-induced cannibalism, showing that the combination can lead to drastic suppression of host populations and even host extinction.