Effects of habitat fragmentation at different trophic levels in insect communities

Abstract

Species experience landscapes differently depending on their needs and behaviors, and on their trophic level. We expect species at high trophic levels in a community to be more sensitive to habitat fragmentation than species at lower trophic levels. But this depends on attributes such as resource breadth, dispersiveness, reproductive rate, and longevity, which may not be related to trophic level. I address the association of fragmentation with trophic level using a literature review of 31 studies of herbivores and their natural enemies, and a case study of the parasitoids associated with the Glanville fritillary butterfly. Measures of species richness or total parasitism in an entire insect community provide the strongest support for the idea that negative effects of fragmentation amplify at higher trophic levels. Generally though, there is great variation among studies, due to variation among species, as well as in designs of both experimental and observational studies.