Evaluating the Non-Consumptive Effects of Insect Predators on Aphids and Aphid-Borne Virus Transmission

Download or read book Evaluating the Non-Consumptive Effects of Insect Predators on Aphids and Aphid-Borne Virus Transmission written by Benjamin Walter Lee and published by . This book was released on 2021 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Predators exhibit "consumptive effects" (CEs) by capturing and consuming prey, while exhibiting "non-consumptive effects" (NCEs) on prey physiology and behavior through failed attacks that influence their perception of risk in the environment. Predatory insects are widely used to control agricultural pests, including insect vectors of pathogens, though their role in affecting pathogen transmission has been poorly understood. This dissertation evaluates a range of predation effects on aphid vectors and their transmission of Pea enation mosaic virus (PEMV), an economically damaging aphid-borne pathogen of legumes grown in the Pacific Northwest USA. The first chapter discusses difficulties in predicting vector-borne virus transmission using mathematical models, as vectors' interactions with other species can unpredictably affect rates of pathogen transmission. The second chapter documents a field study evaluating predator CEs and NCEs on aphid vector abundance, movement, and feeding behavior and how these effects contribute to aphids' ability to transmit PEMV. Analysis using structural equation modeling revealed predators indirectly increased PEMV prevalence by inducing aphids to disperse to new hosts and feed upon parts of the host plant on which pathogen transmission is greater. The third chapter details several greenhouse experiments examining how vector responses to signals of predation risk affect transmission of PEMV. I found that chemical cues left by predators or alarm pheromones released by conspecifics reduced aphids' ability to acquire and transmit PEMV but had no effect on their fecundity or nutrition. The final chapter describes a field study examining how diverse predator communities affect aphids and PEMV transmission. When multiple predator species feed on aphid vectors, their effects on aphid abundance can be synergistic or antagonistic, though the impacts of predator diversity on aphid behavior and transmission efficiency are unknown. I find that predator diversity enhanced aphid suppression but altered aphid behavior in ways that increased virus transmission, resulting in no net change in PEMV prevalence. This final chapter suggests that the benefits of increasing diversity for pest suppression may not similarly influence disease risk. This dissertation improves our understanding of how insect predators affect plant pathogen transmission and will inform management strategies using natural enemies to combat plant pathogens.