Overlap in cave usage and period of activity as factors structuring the interactions between bats and ectoparasites.

Abstract

Bats perform important ecosystem services such as pollination and seed dispersal. Bats are also hosts to obligate ectoparasites, which influence their behavior and, thus, compromise their ecosystem functions. Therefore, the study of the bat-ectoparasitic interaction network and its driven factors is basic for understanding variation in the ecosystem services provided by bats. In this study, we evaluated the structure of the network of interactions between bats and their ectoparasite arthropods, testing the roles of overlap in cave usage and period of activity as factors structuring the interactions. We conducted the study in caves within the Cerrado ecosystem near Brasília, Brazil. Our results show that the bat-ectoparasite network has a modular pattern and is highly specialized. The observed pattern was explained by the greater probability of transmission of ectoparasites among bats sharing the same cave during the same period of the year. Furthermore, our data showed that the rate of bat infestation by different ectoparasite species is related to the degree of exposure of bats according to their abundance and activity period, but not with the number of caves used to roost. Thus, we believe that the frequency of activity and encounters between bats, and therefore the rate of ectoparasite transmission, is an important regulatory mechanism of bat-ectoparasite networks. This ecological mechanism may facilitate the formation of specific interactions by spatial and temporal segregation and co-evolution of parasite species among groups of roosting bats.