Investigating the effects of ophryocystis elektroscirrha on the monarch butterfly (Danaus plexippus)

Monarch butterflies of the genus Danaus are an iconic species that have three large populations spanning three geographic locations in the United States; the west coast of California, the east coast stretching over Florida to the Carolinas, and the Central-Midwest population that migrates every year. Over the past 30 years, some studies have indicated that the monarch population is dwindling due to several factors. These include many abiotic and biotic factors such as parasites, bacteria, viruses, logging in Michoacán (winter roost site), and climate change which are currently having detrimental effects. This study aims to investigate one of these detrimental factors, namely the parasitic infection of young instar larva by an intracellular neogregarine parasite. Ophryocystis elektroscirrha is an intracellular Apicomplexa parasite that infects the larval stages of monarch butterfly development. To assess the pathology that occurs to the larva during parasitic growth, an experimental design was applied that purposely infect larval instar stages 2-5 with varying intensity of O. elektroscirrha spores (2,000, 12,500, 25,000). Histological sections were made and analyzed for micronuclear schizonts where individual specimens were measured and recorded. In order to get a more comprehensive understanding of the pathology occurring, hemolymph smears were taken and immune cell types were counted and identified to gauge the immunological response. I found that despite high infection intensity at various stages there does not appear to be much of a pathological or immunological response from the host organism, with a noticeable exception in stage five larva.