3.8 Wednesday, Jan. 4 Multiple trade-offs among life-history and metabolic traits mitigate the impacts of overwintering microclimate on the fitness of Fall Webworm across its native range. WILLIAMS, C.M.*; CHICK, W.D.; SINCLAIR, B.J.; University of Western Ontario; University of Western Ontario; University of Western Ontario email@example.com
The impact of the environment on distinct physiological and ecological traits, and across life-stages, can result in trade-offs that combine to determine the fitness of individuals and thus population dynamics. We examined the role of local adaptation and plasticity in modifying the life-history and physiological characteristics of a widespread, generalist pest species Hyphantria cunea, Lepidoptera: Arctiidae) from the centre (Columbus, OH [CO]) or northern periphery (Ottawa, ON [OT]) of their range, in response to overwintering microclimate conditions approximating the collection sites (northern or southern treatments), in a reciprocal common garden design. Populations differed in the majority of life-history and metabolic traits, but this differentiation did not appear to be adaptive. Diapause entry was advanced in CO compared to OT populations, which had negative effects on adult size, but larger pupal size in CO pupae compensated for this effect. Pupae facultatively suppressed their metabolism at warm, energetically demanding southern temperatures, which more than compensated for the increased energetic demands of warmer winters, as pupae from the warm southern treatment actually had more energy reserves remaining at the end of winter than did the cooler northern treatment. This species thus has a large repertoire of genotypic and plastic changes to life-history and metabolic traits that render them relatively insensitive to changes in their overwintering thermal environment.