Investigation on patterns of water mite abundance on host damselflies and their effect on mating success.

Abstract

Water mite parasitism is expected to have important effects on damselfly survivorship and reproductive success. The mites drain considerable amounts of bodily fluid from their hosts, increasing greatly in size during the parasitic phase of their life cycle. Studies in the past have repeatedly shown conflicting results regarding the effects of the water mites on their hosts. In order to investigate these opposing ideas, two day trips to Sugar Island in the Michigan Upper Peninsula were scheduled during which damselflies of the species Enallagma hageni were collected at the water's edge, looking for both single and copulating individuals. The data collected was analyzed using Systat. Results showed a moderate correlation between prevalence of parasitism and sex, with greater percentages of females hosting parasites compared to males. Greater abundances of mites were present on the larger damselflies, indicating a significant increasing linear regression of mite load versus body mass. No difference was noted between either males or females in copulation and mite prevalence. While no reproductive consequence was noted in this study on the damselflies hosting parasites, the water mites do negatively affect their hosts in other ways not related to reproduction.