Karst-roosting bats consume medical and agricultural insect pest species in Cambodia

Cavernicolous bat species across much of Southeast Asia are threatened by habitat destruction and fragmentation. Efforts to identify ecosystem services of cave-roosting bats in Cambodia could provide important information on bat ecology and support conservation actions. Therefore, we designed a study to determine dietary habits of cave-roosting insectivorous bats using karst areas in southern Cambodia adjacent to subsistence agricultural lands. We collected guano from 122 captured bats of five species and under three single-genera roosts during the rice-growing season (July-August) of 2017 and successfully extracted and amplified arthropod DNA from 95 samples. Bioinformatic analyses generated 954 Operational Taxonomic Units (OTUs), 169 of which were unique. Across samples, Lepidoptera represented 44.4% of all OTUs (n=75/169) and Diptera was the next most represented at 32.0% of all OTUs. Presence-absence analyses revealed no significant differences in arthropod prey composition among bat species or capture locations. We classified 112 OTUs to species, with 38 (34.0%) identified as known pests (23 crop pest species, 15 general pest species), 21 (18.8%) as disease vectors and 49 (43.8%) as mostly or completely harmless. We found that all five bat species captured during this study consumed major insect pest species, including several Culicidae and Lepidoptera known to cause human diseases and crop damage. We show that karst-roosting bats in southern Cambodia indeed have the potential to provide important ecosystem services, although future work is needed to identify tangible landscape impacts stemming from bat suppression of insect pests.