Parasites are able to alter numerous aspects of their hosts’ life history, behaviour and distribution. One central question in parasitology is to determine the degree of impact that parasites have on their hosts. Laboulbeniales (Fungi: Ascomycota) are ectoparasitic fungi of arthropods. Even though these fungi are widely distributed, little is known about their ecology and their possible physiological effects on their hosts. We used a highly specific bat fly-fungi association to assess the effect of these fungal parasites on their dipteran hosts.

We collected bat flies (Diptera: Nycteribiidae) belonging to two species, Nycteribia schmidlii and Penicillidia conspicua from their bat host Miniopterus schreibersii (Chiroptera: Miniopteridae). We experimentally tested the effect of infection on the lifespan of bat flies.

The prevalence of Laboulbeniales fungi was 17.9% in N. schmidlii and 64.8% in P. conspicua. Two fungi species were identified, Arthrorhynchus eucampsipodae and A. nycteribiae, both showing strict host specificity with N. schmidlii and P. conspicua, respectively. We found that fungal infection reduced by half the survival rate of P. conspicua regardless of sex, whereas N. schmidlii was not affected by the infection. Moreover, the intensity of infection showed negative correlation with the lifespan of P. conspicua.

To our knowledge, this is the first indication that fungal infection can alter bat fly survival and thus may play a significant role in the population dynamics of these bat ectoparasites.