Habitat fragmentation and arthropod community change: Carrion beetles, phoretic mites, and flies

Little is known about the effects of habitat fragmentation on forest insect communities. We studied relationships among carrion beetles (Coleoptera: Silphidae), an insect guild important to decomposition processes in forests, the beetles' phoretic mites, and the beetles' primary competitors, muscoid flies, along an urban-rural gradient of forest fragmentation in central New York State, USA. Species richness of carrion beetle communities was reduced by one-third and beetle abundance by two-thirds in fragmented forests whereas flies were 1.5x more abundant in forest fragments than in contiguous forests. The commensal relationship between carrion beetles and their phoretic mites was more variable in heavily fragmented sites, with beetles typically having unusually low or high mite loads. The beetles thriving in fragmented forests were generally small-bodied habitat generalists. This study indicates that forest fragmentation has a profound impact on carrion beetle communities, although the mechanisms underlying these patterns remain unresolved.