Effects of host state and body condition on parasite infestation of bent-wing bats

Ectoparasites inhabit the body surface or outgrowths of hosts and are usually detrimental to host health and wellbeing. Hosts, however, vary in quality and may lead ectoparasites to aggregate on preferred hosts, resulting in a heterogeneous distribution of parasite load among hosts.

We set out to examine the effects of host individual state and body condition on the parasite load of multiple nycteribiid and streblid bat flies and Spinturnix wing mites on eastern bent-wing bats Miniopterus fuliginosus in a tropical forest in southern Taiwan. We detected a high parasite prevalence of 98.9% among the sampled bats, with nearly 75% of the bats harboring three or more species of parasites. The parasite abundance was higher in the wet season from mid spring to early fall, coinciding with the breeding period of female bats, than in the dry winter season. In both seasonal periods, the overall parasite abundance of adult females was higher than that of adult males. Among the bats, reproductive females, particularly lactating females, exhibited a higher body condition and were generally most infested. The Penicillidia jenynsii and Nycteribia parvula bat flies showed a consistent female-biased infection pattern. The N. allotopa and Ascodipteron speiserianum flies, however, showed a tendency towards bats of a moderate to higher body condition, particularly reproductive females and adult males.

We found an overall positive correlation between parasite abundance and reproductive state and body condition of the host and female-biased parasitism for M. fuliginosus bats. However, the effects of body condition and female-biased infestation appear to be parasite species specific, and suggest that the mobility, life history, and potential inter-species interactions of the parasites may all play important roles.