Predator-prey traits and foraging habitat shape the diet of a common insectivorous bat

Individual and species traits may determine the functional relationships between predators and their prey, with clear consequences for the ecosystem services potentially associated with predation. Bats are well-known potential deliverers of ecosystem services in agroecosystems through predation of pest arthropods that may affect crop production. Here we test the role of individual and prey traits in shaping the dietary habits of the Savi's pipistrelle (Hypsugo savii), a common bat species that frequently occurs in agroecosystems across the Mediterranean area, assessing diet composition and trait-based biases through molecular tools and multivariate testing techniques. DNA metabarcoding identified 173 distinct prey taxa in bats sampled in the Vesuvius National Park (Southern Italy). The diet was strongly dominated by pest insects associated with agricultural areas, which covered 57% of the overall prey diversity, some representing major pests of high economic relevance. The multivariate analyses detected strong relationships between diet composition, sampling date, and individual bat body conditions. Larger bats consumed larger prey items, and prey consumed later in the season (August) were smaller than those eaten in early summer (July) and were typical of less natural habitats. Hypsugo savii is potentially an important pest suppressor in the agroecosystems of the Mediterranean region and the functional relationships between the traits of individual bats and their prey set the basis for a quantitative assessment of the associated ecosystem service. We also remark on the value of bat diet studies in aiding the surveillance of arthropod species relevant to agriculture, human health, and biodiversity conservation.