HABITAT FRAGMENTATION AND PARASITISM OF A FOREST DAMSELFLY

We compared populations of a forest damselfly - Calopteryx maculata - in two kinds of landscapes. In fragmented landscapes, forested foragin g patches were separated from streams (where oviposition and mating oc cur) by up to 500 m of pasture. In non-fragmented landscapes, there wa s continuous forest cover adjacent to streams. The prevalence and inte nsity of midgut infections of a gregarine parasite were significantly lower in the fragmented landscapes than in the non-fragmented landscap es. We have shown elsewhere that in the fragmented landscapes, damself lies move over greater areas to forage than in the non-fragmented land scapes. We postulate that these movements lower the rate of encounter between damselflies and oocysts, thus lowering the prevalence and inte nsity of infection. The differences suggest that actual habitat fragme ntation events would alter the relationship between host and parasite, but that populations of both species would persist after fragmentatio n. Prevalence of parasitism is related to age but we found no residual effects of size on parasitism.