Oviposition behavior and offspring performance in herbivorous insects: consequences of climatic and habitat heterogeneity

Th e preference–performance hypothesis predicts that when female herbivorous insects determine where to position off spring of low mobility, they will select sites that maximize development and survival of those off spring. How this critical relationship responds to variation in climatic and habitat conditions remains untested, however, despite its important consequences for population and evolutionary dynamics. Here we report on 13 years of data totaling 1348 egg clusters of the montane Gillette’s checkerspot butterfl y Euphydryas gillettii (Lepidoptera: Nymphalidae). We used these data to test the hypothesis that, in environments with climatic and habitat heterogeneity, the oviposition behavior–off spring performance relationship should vary in both space and time. Orientation of egg clusters for maximum morning sun exposure is known to aff ect developmental rate. We therefore predicted female preference for morning sun orientation to be variable and a function of climatic and habitat conditions. We found that preference for egg cluster orientation on the leaf tracked the phenology of the start of the female fl ight season but that seasonal temperatures drove most of the variation in egg cluster development time. Th e relationship between behavior and performance was also dependent upon the climatic eff ects on survival; sun-oriented egg clusters had higher survivorship in the coldest year of the four years for which measurements were made. We also examined how conifer cover aff ected larval survival and female oviposition behavior in one year. Females selected oviposition sites in more open habitat. However, when egg clusters were oriented to intercept morning sun, conifer cover increased survivorship to diapause. Finally, we found that predator activity was lower for morning sunoriented egg clusters suggesting that predation patterns may further infl uence habitat selection for oviposition. Th is study exemplifi es how the relationship between oviposition behavior and off spring performance is context-dependent: habitat and climate interact to determine preference–performance outcomes.