Md Kawsar Khan, Shatabdi Paul, Mostakim Rayhan, Marie E. Herberstein

Host-parasite interactions are impacted by climate, which may result variation of parasitism across landscapes and time. Understanding how parasitism varies across these spatio-temporal scales is crucial to predicting how organism will respond to and cope under a rapidly changing climate. Empirical work on how parasitism varies across climates is limited. Here, we examine the variation of parasitism across seasons and identify the likely climatic factors that explain this variation using Agriocnemis femina damselflies and Arrenurus water mite ectoparasites as host-parasite study system. We assessed parasitism in a natural population in a subtropical climate between 2021-2023 and calculated prevalence (percentage of infected individuals) and intensity (the number of parasites on an infected individual) of parasitism across different seasons. Parasite prevalence and intensity were greater during cooler seasons (autumn and winter) compared to hotter seasons (spring and summer). Mean temperature and precipitation were negatively correlated with parasite prevalence whereas only mean precipitation was negatively correlated with parasite intensity. Tropical, Subtropical and Mediterranean countries are predicted to experience extreme climatic events (extreme temperature, less precipitation and frequent drought) as a consequence of anthropogenic climate change, and our finding suggests that this could increase parasitism in aquatic insects.