The Nycteribiidae are obligate blood-sucking Diptera (Hippoboscoidea) flies that parasitize bats. Depending on species, these wingless flies exhibit either high specialism or generalism toward their hosts, which may in turn have important consequences in terms of their associated microbial community structure. Bats have been hypothesized to be reservoirs of numerous infectious agents, some of which have recently emerged in human populations. Thus, bat flies may be important in the epidemiology and transmission of some of these bat-borne infectious diseases, acting either directly as arthropod vectors or indirectly by shaping pathogen communities among bat populations. In addition, bat flies commonly have associations with heritable bacterial endosymbionts that inhabit insect cells and depend on maternal transmission through egg cytoplasm to ensure their transmission. Some of these heritable bacteria are likely obligate mutualists required to support bat fly development, but others are facultative symbionts with unknown effects. Here, we present bacterial community profiles that were obtained from seven bat fly species, representing five genera, parasitizing bats from the Malagasy region. The observed bacterial diversity includes Rickettsia, Wolbachia, and several Arsenophonus-like organisms, as well as other members of the Enterobacteriales and a widespread association of Bartonella bacteria from bat flies of all five genera. Using the well-described host specificity of these flies and data on community structure from selected bacterial taxa with either vertical or horizontal transmission, we show that host/vector specificity and transmission mode are important drivers of bacterial community structure.
Bats are increasingly recognized as natural reservoirs of a large number of emerging infectious agents (1-4). It is thus implicit that vectors of bat-borne disease will play important roles in the epidemiology and dynamics of infectious agents that can eventually emerge in human populations. Further, bats are hosts to different ectoparasites, including mites, fleas, ticks, and bat flies (5, 6). Bat flies (Diptera: Hippoboscoidea) are obligate blood-sucking parasites that are classically divided into two families-the Streblidae and the Nycteribiidae (7). Together, the Hippoboscidae (louse or ked flies), Streblidae, and Nycteribiidae are referred to as the Pupipara sensu stricto due to their adenotrophic viviparity, where all larval developmental stages occur within the adult female's body and the larva are nourished by milk glands until they are ready to pupate. This particularity of the Pupipara sensu stricto is thought to promote vertical parasite transmission, thus influencing the epidemiological role of these vectors in disease transmission.To date, studies of microorganisms associated with nycteribiids have mainly focused on two groups of bacteria-Bartonella spp. (8-11) and Arsenophonus-like organisms (referred to here as ALOs) (12-15). These bacterial genera offer contrasting model systems for investigating t...