Drivers of bat fly diversity and prevalence of six Rhinolophus bat species in southern Africa.

Abstract

Demographic and ecological characteristics render obligate cave roosting bats highly susceptible to infestation by ectoparasites. However, the patterns and factors of ectoparasite loads among bat host species are understudied, particularly in the Old World. I tested predictions of habitat heterogeneity, host sex, body size hypotheses to explain parasitic bat fly (Streblidae and Nycteribiidae) abundance, morphospecies richness and prevalence on six Rhinolophus bat species in southern Africa. I sampled and classified 930 bat flies to six morphospecies (3 streblids and 3 nycteribiids) captured on 333 bats at 20 sites in eight biomes. In support of the habitat heterogeneity hypothesis, there were significantly positive relationships between habitat heterogeneity and bat fly abundance, morphospecies richness and prevalence. In support of the host body size hypothesis, there were significantly positive relationships between host body condition and bat fly abundance, morphospecies richness and prevalence. By contrast, there was little evidence that parasitic flies preferred either male or female bats. Recursive partitioning analysis showed that the most significant predictor of bat fly abundance and morphospecies richness was habitat heterogeneity, specifically the number of land cover classes surrounding bat roosts. My results suggest that land use and biome characteristics at the meso-scale, and to a lesser degree biotic processes at the local scale, mediate bat fly abundance and morphospecies richness on rhinolophid bats. Specifically, structurally heterogeneous and complex habitats increase the number of niches available for bat species as well as their prey, which, in turn, may favour diverse bat fly populations. Thus, factors responsible for driving bat diversity may also drive bat fly diversity. Future studies should focus on other families of cave-roosting bats, as well as endoparasites, to better understand the mechanisms responsible for ectoparasitism in Old World bats.