Trichobius joblingi, Aspidoptera falcata, and Megistopoda proxima (Diptera: Streblidae) parasitic on Carollia perspicillata and Sturnira lillium (Chiroptera : Phyllostomidae) in southeastern Brazil: Sex ratios, seasonality,host site preference, and effect of parasitism on the host

This note examines the effect of parasitism on host size, the preference of the parasite for a specific host body area, and the seasonal abundance for the 3 most abundant bat flies (i.e., Trichobius joblingi Wenzel, a parasit e of the bat Carollia perspicillata [Linnaeus], and Aspidoptera falcata Wen zel and Megistopoda proxima [Seguy], parasites on Sturnira lilium [Geoffroy ]). Trichobius joblingi and A. falcata are moderately dorsoventrally flatte ned and were collected on the wing membranes of their hosts, and M. proxima is moderately laterally compressed, has long, thin hind legs, and was coll ected in the body fur of the host. These 3 parasites also showed distinct s easonal patterns. There was a significant negative con elation between the simultaneous occurrence of A. falcata and M. proxima on the host. Parasitis m by M. proxima was correlated with a significant weight loss in male S. li lium, which may reflect the large size, high activity, and constant feeding of this parasite, thereby causing a significant negative effect on the hos t. Sex ratios favoring male flies could be explained by the tendency of fem ale flies to leave the host immediately before the bat leaves the shelter i n search for food or immediately after bats are collected but could also be a consequence of higher mortality among females, especially gravid ones. F inally, collecting may have influenced the skewed sex ratio because male fl ies. being more active, were more evident to the collector.