Meeting Abstract
The effects of large-scale changes in global climate on biodiversity have received much attention, but the more acute form of climate change that results from local habitat alteration has been less explored. Each time a forest is cut, thinned, fragmented or otherwise altered in structure, local climates and microclimates change. Such changes can have both direct (e.g., on body temperature) and indirect (e.g., on plant traits) effects on herbivorous insects. In this study, we formulate an eco-physiological framework to study the impacts of forest change on herbivorous insects. Specifically, we predict that if tropical forest caterpillars are climate and resource specialists, then they should suffer reduced performance outside of mature forest-like conditions, such as those found in young secondary forests. We test this idea with a field experiment on the performance of the caterpillar Rothschildia lebeau feeding on its host plant Casearia nitida in two different aged forests in Area de Conservacion Guanacaste, Costa Rica. Compared to more mature closed-canopy forest, we found that (1) ambient conditions were hotter, drier, and more variable; (2) caterpillar growth, development and survival were reduced; and (3) leaves were thicker, tougher and drier in younger forest. In addition, variation in caterpillar performance was significantly related to variation in leaf traits. Based on the available evidence, we conclude that reduced caterpillar performance in younger forest could have been driven by differences in climate, leaf traits (which may be tied to climate), or both.
