Diet of Insectivorous Bats (Mammalia: Chiroptera) from Nepal

Insectivorous bats play an essential role in suppressing pests and controlling disease vectors, yet their dietary habits remain understudied in Nepal. Thus far, there have been three theses and a single study on insectivorous bat diets from the country. To address this gap, guano samples collected during bat surveys from March 2020 to March 2023 in four regions: Shivapuri Nagarjun National Park (Kathmandu District), Makalu Barun National Park (Sankhuwasabha District); Manthali (Ramechhap District), and Bajrabarahi Forest (Lalitpur District), were analyzed. The diet composition of ten bat species from four families: Rhinolophidae (Rhinolophus pusillus, R. sinicus), Miniopteridae (Miniopterus fuliginosus), Hipposideridae (Hipposideros gentilis), and Vespertilionidae (Pipistrellus javanicus, Pipistrellus sp., Myotis csorbai, M. sicarius, Myotis sp., Submyotodon caliginosus) was assessed, with the diets of M. csorbai, M. sicarius, and S. caliginosus documented for the first time. Dietary analysis of 176 guano pellets revealed the presence of seven insect orders, with Diptera and Lepidoptera detected in all samples, followed by Coleoptera (80%), Neuroptera (40%), Hemiptera (30%), Psocodea (20%), and Hymenoptera (20%). A single mite (Acari) was also detected, likely ingested incidentally during grooming or alongside prey. Percentage volume analyses revealed species-specific foraging preferences among insectivorous bats, complementing frequency data. Hipposideros gentilis showed a marked preference for Lepidoptera (83.8%), while M. fuliginosus, R. lepidus, and P. coromandra also favored Lepidoptera, though to a lesser extent (43.5%, 46.0%, and 39.4%, respectively). Rhinolophus affinis consumed only Diptera, which also dominated the diets of R. pusillus (48.6%), P. javanicus (40.0%), an unidentified Pipistrellus species (37.0%), M. csorbai (56.2%), another unidentified Myotis species (68.8%), and S. caliginosus (56.0%). In contrast, R. sinicus and M. sicarius had diets dominated by Coleoptera (61.0% and 50.5%, respectively), with M. sicarius exhibiting the broadest dietary range, consuming all seven identified insect orders. These dietary compositions suggest that the studied bat species employ diverse foraging strategies, including aerial hawking, foliage gleaning, ground gleaning, and trawling. The presence of mosquitoes in the diet of M. fuliginosus, R. lepidus, R. pusillus, P. javanicus, Pipistrellus sp., M. csorbai, M. sicarius, Myotis sp., and S. caliginosus; pests from the families Miridae and Aphididae in the diet of R. lepidus and Pipistrellus sp.; and scarab beetles in the diet of R. sinicus, P. javanicus, Pipistrellus sp., M. csorbai, M. sicarius, and S. caliginosus underscores the role of bats in regulating disease vectors and agricultural pests. Such findings are essential for fostering positive attitudes toward bats among local communities — an important step toward ensuring their long-term conservation in Nepal, where their ecological and economic benefits are often overlooked.