Host Abundance Predicts Interactive Roles in Neotropical Bat-Bat Fly Interactions.

Host functional traits are known to shape host-parasite interactions across multiple taxa. For bats, ectoparasite loads are often regulated by host body size, diet, longevity, and roosting ecology. Therefore, Neotropical bats represent an ideal system for testing host-parasite interaction hypotheses, as the second more speciose group of mammals, with a high level of functional diversity. Their primary ectoparasites are highly host-specific hematophagous bat flies, who spend the most part of their lifetime on their hosts. Here, we evaluated whether bat functional traits influence their importance as hosts within Neotropical bat-bat fly interactions. We predicted that larger carnivorous, longer-lived, cavity-roosting bats would exhibit higher host importance. Using interaction and trait data from published datasets, we constructed a unified interaction network for Neotropical bats and bat flies, calculated network metrics and used generalized additive mixed models to test how host traits define host importance in the network. Trophic level was the only trait with a significant effect, with carnivorous bats significantly less important than both herbivorous and omnivorous species. Although host traits such as body size and roosting behavior are known to influence parasite loads in bats, we suggest that host abundance is the main driver for host importance in the network, since carnivorous bats are the most rare Neotropical species. Therefore, in cases of host decline or local extinction, highly abundant bat species may serve as reservoirs for displaced parasites, promoting their persistence and redistribution within the remaining host community.