Conventional Agriculture Decreases Diversity of Gut Bacteria in Foraging Bats

September 29, 2021 | Bats foraging in chemical-intensive banana plantations have much less gut diversity than bats foraging in organic banana fields and natural forestland, finds research published in Frontiers in Ecology and Evolution. Although there is increasing recognition that a diet of conventional, chemically grown food leads to adverse disruptions of the gut microbiome (also known as dysbiosis), little research has been conducted on the effect of production practices on the gut of wild foraging species. Researchers focused their investigation on Pallas’s long-tongued bat (Glossophaga soricina), a nectar feeding bat native to Central and South America. The bat is highly adapted to human environments, sustaining populations in both conventional and organic banana plantations, as well as surrounding forest land. For the study, researchers trapped nearly 200 bats across the country of Costa Rica over a 22-month time span. After trapping, physiological characteristics, like size and body weight, were measured, and bat guano was analyzed for its microbial population. All sampled bats were released back into their habitat. Bats that forage in agricultural land—whether organic or conventional, were found to be overall larger in size and weight than bats that live primarily in the forest. This was likely a result of a diet heavily reliant on the nectar from banana plants. However, bats in organic plantations have significantly higher levels of gut biodiversity than those in conventional plantations (based on a range of analyses, including observed amplicon sequence variants, Shannon diversity index, and Faith’s Phylogenetic Diversity index). Gut diversity in organic bats is found to be similar to the diversity analyzed in forest bats. The study indicates that it is likely that organic practices are maintaining a “high diversity of commensal microbiota,” while on the other hand, “less diverse gut microbiota in bats foraging in conventional monocultures may suggest that these habitats potentially have negative physiological consequences for the animals (e.g., gut inflammation and metabolic disease), and may act as an ecological trap.” [Alpizar, Priscilla et al. Agricultural Fast Food: Bats Feeding in Banana Monocultures Are Heavier but Have Less Diverse Gut Microbiota. Frontiers in Ecology and Evolution. September 2021.]