SELFCURE: Evolutionary and cognitive processes underlying self-medication of immune-challenged bats

Project leader: Ralph Simon
Project members: Ralph Simon, Julian Deyerler
Start date: 1. November 2023
Funding source: Human Frontier Science Program

Abstract

Plant medicinal properties are used by a diverse range of animal taxa. Chimpanzees consume hairy Aspilia leaves when suffering from intestinal parasites, Kodiak bears use Ligustium roots against ectoparasites, and monarch butterflies prevent infection in their offspring by laying their eggs on milkweed, a plant toxic to protozoans. Self-medication behaviors provide an effective mechanism to minimize infection load. But despite its eco-evolutionary importance, we lack clear understanding of how behaviors associated with self-medication evolve. Importantly, animals may possess either an innate mechanism to search for medicinal food items, or they may learn individually or through others to associate specific foods with specific cures. Bats are a especially relevant group to study the mechanisms underlying self-medication. They harbor diverse parasites, feed on a wide variety of foods and, due to their cognitive capacities and extraordinary longevity, have high potential to learn to associate specific food resources with curative properties. Phyllostomid fruit bats in particular are ideal for investigation given the wide variety of plants that they have access to in the Neotropical rainforest. Using state-of-the-art tracking techniques, AI-based individual recognition, and targeted and -omics approaches for characterizing immunity and parasites, we propose to investigate the mechanisms underlying self-medication in phyllostomid bats. First, we will determine the immune state, parasite diversity, and nutritional diversity of wild bat populations and investigate potential links between immunity, infection, and certain food plants. Next, by testing immune-challenged and control-treated individual bats on natural and artificially-created medicinal food preferences, we will shed light on the role of learning vs innate mechanisms in self-medication. By tracking groups of bats through a rainforest site that has been studied long-term with fully mapped fruiting tree species, we have the unique opportunity to assess whether immune-challenged individuals switch to a diet with medicinal compounds. Finally, by tracking experimentally immune-challenged and experimentally cured bats trained on artificial sonar beacons indicating the presence of medicinal foods in the wild, we will assess how information regarding self-medication can spread through a bat social network.