Differences in gregarine parasite load between male and female Calopteryx maculata

Abstract

Damselflies and other insects of the order Odonata are frequently parasitized by gregarine protists. In the trophozoite stage of the gregarine life cycle, the parasite feeds on the contents of the host’s gut and negatively affect its reproductive success. Possibly as a result of its impacts on the host’s reproductive system, levels of gregarine parasitism has been observed to differ between male and female damselflies. We aimed to measure relative levels of gregarine parasitism of male and female damselflies of the species Calopteryx maculata . In order to do this, we collected damselflies at multiple sites in Michigan’s Maple River and dissected individuals to observe the presence of gregarine parasites. Our results indicate that females experience significantly higher levels of gregarine parasitism than their male counterparts. We propose that this difference is the result of increased levels of migratory behavior in female damselflies due to increased parental investment.