Gregarines: Their Effects on Damselflies (Odonata: Zygoptera)

Abstract

Abstract Adults of the damselfly Pyrrhosoma nymphula (Sulzer) were to a great extent found to have their midgut infected with a eugregarine Hoplorhynchus oligacanthus (Siebold). Heavy infestation seriously damaged the gut epithelium, and the viability of the host was estimated to be reduced. Marking experiments have revealed that individuals which attained great adult age were either lightly infected or non-infected, or they were thought to have been infected late in their adult life. The conclusion is that the eugregarine infestation apparently reduces the longevity of adults when other conditions are sub-optimum.