Reynaud, B. | Search bioRxiv

bioRxiv2025

Urban bats change the menu: dietary plasticity across human-modified landscapes of a tropical island

In a rapidly urbanizing world, research on dietary habits of wildlife is essential to understand how plastic behaviors may guide evolutionary trajectories of endangered animal species. Bats are very sensitive to habitat destruction and land-use change, although some species have shown the capacity for adaptation to urban life. In this study, we tested to what extent urban insectivorous bats modify their feeding strategies in a recently human-modified tropical insular ecosystem. Using a DNA metabarcoding approach on fecal samples collected in seven roosts, we analyzed the dietary niche of free-tailed bats (Mormopterus francoismoutoui) endemic to Reunion Island. Our results revealed a wide dietary niche, including 174 arthropod species in 12 orders, among which lepidopterans were predominant. We identified several crop pests and disease vectors, highlighting the central role of this bat species for agroecology and epidemiology concerns. Our study also highlighted potential sex- and reproduction-related dietary strategies. Moreover, we found that agriculture areas, inferred from land cover surrounding bat roosts, were associated with higher relative abundance of Lepidoptera in the diet of bats. In contrast, bats roosting in urban areas increased their consumption of Blattodea. As Reunion free-tailed bats roost and thrive in human-modified landscapes, understanding the consequences of this dietary plasticity for bat health and fitness will be necessary for urban evolutionary research and conservation actions.

ecology↗

bioRxiv2024

Olfaction in Tephritidae: a balance between detection and discrimination

Phytophagous insects are capable of detecting and locating suitable hosts, which emit volatile compounds. Polyphagous species appear to have a complex olfactory strategy given that their numerous hosts have diverse emission profiles. In particular, their hosts volatile emissions share some of the same compounds, providing chemical bridges between them. However, the behavioural plasticity observed in insect host selection suggests that other volatiles have a complementary role. Here we explore how the specialization of polyphagous Tephritidae fruit fly in detecting and discriminating between host fruits has driven their chemical selectivity. The volatile emissions from intact or mechanically damaged fruit of 28 different species were analysed using gas chromatography-mass spectrometry and fed into a neuronal model of an olfactory system. We predicted in silico a functional trade-off between the two tasks, with optimal performance depending on detecting a higher proportion of shared fruit compounds, but with lower sensitivity compared to unshared compounds, or vice-versa. Using triple point electroantennography and a behavioural assay, we studied the olfactory response of Tephritidae fruit fly species that oviposit on fruit. Amplitude of the olfactory responses of eight species were negatively correlated with the compounds degree of sharedness among fruit emissions, while response probability was previously shown to correlate positively with a similar metric. A dose-dependent switch in the flys preference confirmed the ecological importance of both shared and unshared fruit compounds. Thus, we propose that insect olfactory systems are chemically tuned to detect suitable hosts and accurately discriminate between them.

ecology↗