Tracking host use by bat ectoparasites with stable isotope analysis

We used C and N stable isotopes of nectarivorous bats and their ectoparasites to determine the extent to which parasites depend on the host individual for food. The difference in stable isotope values between parasites and host tissues (Delta C-13 and Delta N-15) was used as a proxy of host use. First, we tested the hypothesis that movement among individual Mexican long-tongued bats (Choeronycteris mexicana Tschudi, 1844) is more likely to occur in winged flies than in mites as indicated by higher host-parasite isotopic Euclidian distance (ED). Second, we tested the hypothesis that ectoparasite species in two coexisting bat species representing the C-3 (Geoffroy's tailless bat, Anoura geoffroyi Gray, 1838) and the CAM (lesser long-nosed bat, Leptonycteris yerbabuenae Martinez and Villa-R., 1940) food chains were monoxenous as indicated by their isotopic values. We also examined Delta C-13 and Delta N-15 of individual parasites in relation to C-13 and N-15 reference enrichment factors as an indication of host switching. In general, flies in C. mexicana had higher ED and wider ranges of individual Delta C-13 and Delta N-15 than mites, suggesting that host switching occurred to a larger extent. Most ectoparasites species collected in both coexisting bats were monoxenous, but one fly species appears to be oligoxenous. Individual Delta C-13 and Delta N-15 values varied widely in these parasite species, suggesting movements within species hosts.