Parasites in peril: abundance of batflies (Diptera: Nycteribiidae) declines along an urbanisation gradient

Urbanisation has a wide range of impacts on biodiversity, but its effects on parasitic arthropods, particularly those of bats, remain poorly studied. Ectoparasites of the large-footed myotis (Myotis macropus) in eastern Australia were sampled from 10 roost sites across an urban gradient. In total, 265 bats were examined and 447 ectoparasites were collected, comprising three species of Hippoboscoidea: Basilia hamsmithi (Nycteribiidae), Penicillidia setosala (Nycteribiidae), Brachytarsina amboinensis (Streblidae), and an acarine, Spinturnix novaehollandiae (Mesostigmata, Spinturnicidae). Degree of urbanisation was found to have a significant effect on the abundance of the batfly B. hamsmithi but had no significant effect on the abundance of the wing mite S. novaehollandiae. We hypothesise that this is due to differences in the life history of these two species and the advantage components of these differences confer in exploiting variations in host roost habits. The prevalence of the batfly B. hamsmithi was high in urban sites but comparatively low in suburban and non-urban sites. Mass, sex, and body condition were found to have no significant impact on either the parasite load or the chance of infestation. Both P. setosala and B. amboinensis were recorded from M. macropus for the first time, though only in small numbers. They were associated with mixed-species roosts in a suburban site and are evidence of parasite spillover between sympatric bat species.