Patterns of Gregarine Parasitism in Damselflies

December 2023
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Damselflies are close relatives of dragonflies, and both are part of the order Odonata. Gregarines are a type of intestinal parasite found in invertebrates and are prevalent in damselflies. In this study, data was collected to examine patterns of prevalence and intensity and identify patterns of infection in damselflies. Three factors were studied to determine their effects on gregarine infections. The factors were season, sex, and pollution. This study examined gregarine infections in 242 individuals. The two most common species Enallagma civile and Ischnura posita were represented in two primary locations. These sites were the rural environment of Cook Pond, and the suburban environment of Elkins Lake. Damselflies were dissected and examined for gregarine infection from March 2022 through October 2022. The collection process was complicated by a drought that occurred during the middle season, which likely affected the results. Despite this, the collected data yielded several noteworthy results. The first was that infection rates shifted across seasons, with intensity and prevalence varying greatly at different points. Though these findings could have been influenced by the drought, it would take a longitudinal study to conclude. The second noteworthy finding was that females had a higher prevalence in Elkins, while males had a higher prevalence in Cook Pond. The final noteworthy finding was that Cook Pond had a higher prevalence and intensity, despite water data showing it to be less polluted of the two sites.