Interaction networks between bats (Mammalia: Chiroptera) and ectoparasitic flies (Diptera: Hippoboscoidea) in the Colombian Orinoquia Region

The study of host-parasite interactions is key to understanding ecological interactions since parasites play a crucial role in the regulation of populations of host species. The families Nycteribiidae and Streblidae (Diptera: Hippoboscoidea) are ectoparasitic flies specific to bats, which have evolved adaptations to their host. The host-parasite interactions are formed by coevolutionary processes and illustrate the current and historical associations between the species involved. For this reason, the use of ecological networks in parasite-host interactions allows us to elucidate how the structure of their interactions respond to biotic and abiotic factors. In the present study, we evaluated changes in the fly-bat interaction networks in two contrasting landscapes in the Department of Arauca of the Colombian Orinoquia Region. The first landscape is composed of savannas and alluvial forests and the second with anthropogenic disturbances composed of cocoa crops, livestock areas and human settlements. We used mist nets to capture bats and collect their respective parasitic flies. Using this data, we built a bipartite interaction network for each landscape, and we calculated the main metrics of each network. 19.8% of the 524 bats captured presented ectoparasitic flies, with a total of 326 flies belonging to nine genera of Streblidae and one genus of Nycteribiidae. The diversity and prevalence of ectoparasitic flies of bats was higher for the disturbed landscape in contrast to savannas and forests. The networks of both landscapes were characterized by being highly specialized and modular. Nonetheless, the network obtained in the savannas and alluvial forests showed greater specialization, and the landscape with anthropogenic impact presented greater modularity. Our results confirm the high specialization and modularity that characterizes the ectoparasitic bat-fly antagonistic network. Also, we provided new observations suggesting that a degraded landscape may affect the bat hosts and favors overcrowding and, consequently, the exchange of ectoparasites between bat species, reducing the level of specialization and promoting the increased prevalence of bat ectoparasitic flies.