Evidence of Escherichia coli Regulating Drosophila melanogaster Behavior

Abstract

Chemosensory systems are critical for insect survival, enabling host seeking, food acquisition, and oviposition site selection. While insect-associated microbes are known to influence host development and immunity, their role in modulating chemosensory behavior remains poorly understood. Here, we demonstrate that Escherichia coli, a bacterium identified in non-gut tissues of Aedes albopictus and experimentally reintroduced into axenic Drosophila melanogaster, alters both larval and adult sensory-driven behaviors. In larvae, E. coli infection modified phototaxis and mechanosensory responses across genotypes, while tunneling and thermosensory behaviors were specifically dependent on the ionotropic receptor co-receptor IR25a. In adults, E. coli increased attraction to fermentation cues (apple cider vinegar, ethanol) and enhanced sucrose consumption in wild-type and Orco-deficient flies, but not in IR25a-deficient mutants. Gas chromatography-mass spectrometry revealed that E. coli shifted cuticular hydrocarbon composition toward shorter-chain alkanes and increased the sex pheromone 9-tricosene in an IR25a-dependent manner. Together, these findings show that E. coli broadly reprograms insect sensory behavior, with IR25a serving as a critical mediator of microbial influence on chemosensory and physiological traits. This work identifies a previously unrecognized role for E. coli in shaping insect behavior and chemical ecology, providing a foundation for investigating microbial contributions to host-microbe coevolution and for exploring microbial cues as novel, environmentally sustainable tools for insect control. ImportanceInsects depend on their sense of smell and taste to find food, mates, and safe places to reproduce. These behaviors drive the spread of insect-borne diseases and cause major agricultural losses worldwide. Our work shows that a common bacterium, Escherichia coli, can reshape insect sensory behaviors, influencing how flies respond to light, temperature, food, and even the chemical signals on their outer surface that control mating. Importantly, these effects are linked to a specific sensory receptor, IR25a, which is conserved across many insect species. This finding reveals a previously unknown role for microbes in fine-tuning insect behavior. Understanding how bacteria influence insect sensory systems not only provides insight into host-microbe interactions but also opens the door to new, environmentally friendly ways of managing insect pests by targeting their behavior rather than killing them outright.