Consequences of ectoparasite infection in damselflies
Interspecific and intraspecific variation of parasitism can have different fitness costs between sexes and across developmental stages. This variation could arise because of individual differences in immunity and resistance. Theory predicts that the extent of parasitism and its costs will be greater in males than females. This prediction has been tested and verified in vertebrates. In insects, however, contradictory evidence has been found in different taxa. We tested this prediction on Agriocnemis damselflies, which are parasitized by Arrenurus mite ectoparasite. We quantified the parasite prevalence i.e., the proportion of parasitised individuals and intensity, i.e., the number of parasites per infected damselfly in Agriocnemis femina and Agriocnemis pygmaea damselflies from eleven field sites. In contrast to our predictions, we found no difference in parasite prevalence between sexes. We found that prevalence was greater in immature females than mature females. However, we found that parasite intensity was more significant in females than males and in immature females than mature females. We further tested whether parasitism reduces longevity in Agriocnemis femina damselflies. We found that parasitism significantly reduced longevity in males compared to females and in immature females than mature females. Overall, our study provides evidence that parasitism impacts sexes and developmental stages differentially.