Parasite preferences for large host body size can drive overdispersion in a fly-mite association

Body size generally correlates intraspecifically with insect fitness but can also correlate with parasite abundance (number of parasites). Host preferences by parasites, and variation in host immunity, could contribute to this trend. We investigated the effect of host size on mite-fly interactions (Macrocheles sub-badius and Drosophila nigrospiracula). Mites strongly preferred to infect larger flies in pair-wise choices, and larger flies were more likely to be infected and acquired more mites in infection microcosms. Preferences of parasites resulted in size-biased infection outcomes. We discuss the implications of this heterogeneity in infection on parasite overdispersion and fly populations. (c) 2023 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Automated summary

Body size is generally correlated with insect fitness and can also be related to the abundance of parasites. The preferences of parasites and variation in host immunity may contribute to this trend. In this study, we investigated the impact of host size on mite-fly interactions, finding that mites showed a strong preference for infecting larger flies and larger flies were more susceptible to infection and acquired more mites. These preferences of parasites resulted in a biased infection outcome based on host size. The implications of this heterogeneity on parasite overdispersion and fly populations are discussed.