A trait-based understanding of the vulnerability of a paleotropical moth community to predation by a sympatric bat with flexible foraging strategies

Abstract

O_LIPrey profitability for a predator hunting diverse prey varies with species and seasons. Whereas prey selection by aerial-hawking or gleaning bats is well established, this is challenging to establish in species that adopt both these strategies flexibly. Measurable prey traits coupled with availability in the foraging grounds help characterize the vulnerability of prey species to predation. C_LIO_LIIn the Western Ghats of India, a global biodiversity hotspot, we studied an anthropogenic landscape, where insectivorous bats are abundant and diverse, but their impact on moth communities is little understood. We investigated the morphological traits of a sympatric moth community that make them more vulnerable to predation by Megaderma spasma, a bat with flexible foraging strategies. We also established the seasonal composition of moth prey in the diet of the bat. C_LIO_LIWe analyzed the discarded prey remains from several roosts, collected over three years, for seasonal patterns in the diet and selective hunting. Through light-trapping, we collected moth specimens in different seasons to assess the morphological traits of the moth community available in the foraging area of the bat. C_LIO_LIThe traits likely to affect the profitability of prey moths were measured: forewing length, hindwing length, wingspan, and body length (a proxy for body size); forewing area, hindwing area, maneuverability, and wing loading (as a proxy for evasive flight capability), and forewing aspect ratio (as a proxy for wing shape). C_LIO_LIOur results showed that consumed moth prey diversity varies seasonally, with moths belonging to the Hepialidae family being preferred in the wet season. Moths belonging to the Sphingidae family were the most abundant in the diet, followed by Erebidae and Hepialidae. Sphingid moths have the lowest maneuverability, and highest forewing aspect ratio; the Hepialidae moths have the maximum body size followed by Sphingids thus confirming our hypothesis that larger moths with low evasive capabilities are more vulnerable to predation. C_LIO_LIAssessing vulnerability at the prey community level, we establish a framework for future research on moth-bat interactions from the diverse and less-explored paleotropical communities. Additionally, the study reiterates the usefulness of trait-based approaches to understanding prey-predator dynamics. C_LI