Parasitoid and host nutritional physiology in behavioral ecology

Nutrient acquisition and allocation critically impacts the fitness of all organisms. However, distinguishing between competing hypotheses about metabolic strategies requires mechanistic details on the physiological requirements and constraints under which the organism exists. Parasitoids acquire nutrients during both their larval stage and as adults. In this chapter, we first explore differences in the acquisition strategies of koinobionts and idiobionts and the physiological adaptations parasitoids have evolved to manipulate host nutrient stores for their own fitness. We then relate these larval strategies to nutrient acquisition strategies during the adult stage by revisiting the link between reproduction (ovigeny index), host-feeding behavior, and oosorption. We conclude our discussion by examining how nutritional interactions potentially impact on other aspects of parasitoid and host fitness. Overall, we argue that the combination of top-down evolutionary approaches with bottom-up insights into physiology and molecular mechanisms offers new avenues for understanding the complex syndromes of the idiobiont and koinobiont life history dichotomy.