Higher gregarine parasitism often in sibling species of host damselflies with smaller geographical distributions

摘要

1. This study investigated inter-speci?c variation in parasitism by gregarines (Eugregarinorida: Actinocephalidae), among sibling species of damsel?ies (Odonata: Zygoptera), in relation to relative size of geographical ranges of host species. 2. Gregarines are considered generalist parasites, particularly for taxonomically related host species collected at the same sites or area. Prevalence and median intensity of gregarine parasitism was obtained for 1338 adult damsel?ies, representing 14 species (7 sibling species pairs) across 3 families within the suborder Zygoptera. Damsel?ies were collected at three local sites in Southeastern Ontario, during the same periods over the season. 3. Five out of seven species pairs had signi?cant differences in parasitism between sibling species. The less widespread host species was the more parasitised for three species pairs with signi?cant differences in gregarine prevalence, and for two species pairs with differences in median intensity. The more widespread host had a higher intensity of infection as expected, in two species pairs. 4. Future studies on ecological determinants of parasitism among related species should examine robust measures of abundance of species and representation of species regionally.