Relationship Between Behavior and Physiology in an Invasive Pest Species: Oviposition Site Selection and Temperature-Dependent Development of the Oriental Fruit Moth (Lepidoptera: Tortricidae)

Abstract

Oviposition site selection is crucial for the reproductive success of a herbivore insect species with relatively sedentary larvae. The optimal oviposition theory, i.e., the preference-performance hypothesis, has thus far mainly been tested with a focus on nutritional quality of the host. This study investigates whether female oriental fruit moth Grapholita (Cydia) molesta choose a microhabitat for oviposition characterized by a temperature range within which their offspring perform best. Thermal preferences of females during oviposition were assessed in a circular temperature gradient arena. Offspring performance and survival were assessed under different constant temperature conditions. Females preferred oviposition sites of approximately 30 degrees C over lower and higher temperatures. At this temperature, egg, larval, and pupal development was significantly faster than at 22 and 25 degrees C, and larval development was also faster than at 33 degrees C. At 30 degrees C and at the lower temperatures tested, survival of eggs and larvae was significantly higher than at 33 degrees C, whereas development was precluded at 35 degrees C. Furthermore, female pupal weight attained at 30 and 33 degrees C exceeded that reached at the lower temperatures tested. Considering the potentially reduced predation risk caused by the shorter developmental time of eggs and larvae, the laboratory data suggest that this species maximizes its fitness by selecting a thermally optimal environment for its offspring, supporting the optimal oviposition theory. Conversely, it is known that the codling moth (C. pomonella) lacks a mechanism to avoid temperatures lethal to progeny development, which may reflect the differences in geographic ranges of these tortricids.