Seasons influence acarine infestation in bats from tropical dry forests of Western Mexico

Bats are parasitized by a wide variety of ectoparasite groups, including mites and ticks (Acari). In temperate regions, infestation patterns are regulated by the host reproductive cycle, which results in parasite reproduction peaking during bat pregnancy and lactation, and declines in winter, when bats are hibernating. The host-parasite dynamics in tropical bat assemblages are less known, and might show more complexity due to the importance of biotic factors over abiotic ones in influencing community dynamics. In this study, we test the hypothesis that parasite fluctuations across the year will peak in the wet season in a tropical dry forest area, when food resources for bats are more abundant and parasites would be favoured accordingly. To test this hypothesis, we assessed the presence and abundance of mites and ticks in one nectarivorous – Leptonycteris yerbabuenae (Martínez and Villa-R) – and three insectivorous – Pteronotus davyi (Gray), P. parnellii (Gray) and P. personatus (Wagner) – bat species. We collected 3005 acarine specimens belonging to 18 species and 12 genera from 412 bats. We did not find significant seasonal variation in most cases. However, the prevalence, mean abundance and intensity of eight acarine species were significantly higher during one of the seasons. In P. parnellii, percentage of infested bats, mean number of acarines per examined individual host, and mean number of acarines per infested individual host were significantly higher during the wet season. However, the percentage of infested individuals of L. yerbabuenae was higher during the dry season, while for P. davyi and P. personatus it was almost the same in both seasons. The actual number of acarine species was also significantly higher during the wet season in the three Pteronotus species whereas in L. yerbabuenae this was higher in the dry season. Our study contributes to shed light on little known host-parasite relationships in tropical forests, highlights the relevance of biotic and abiotic factors on parasitic interactions and provides information on acarine ecology in relation to seasonality in a tropical dry forest.