Diversity of the Cnaphalocrocis medinalis gut bacterial community and its contribution to reproduction

The rice leaf roller, Cnaphalocrocis medinalis, is a notorious migratory rice pest whose high reproductive rate drives population growth. However, the role of its gut microbiota in regulating reproduction remains poorly understood. Here, we demonstrate that gut bacteria are essential for the fecundity of C. medinalis under nutrient stress. Depleting gut bacteria severely impaired reproduction, while reintroducing two key symbionts, Enterobacter bugandensis and Enterobacter roggenkampii (isolated from laboratory and field C. medinalis adult populations, respectively), significantly restored reproductive capacity under low-nutrient conditions. These bacteria were predominantly located in the female adult gut. In contrast, monoassociation with Providencia rettgeri substantially reduced fecundity even under normal nutrient conditions. Our work highlights the contribution of gut bacteria in lepidopteran insect reproduction and provides novel insights into gut microbe-host symbiosis as well as host nutritional adaptation.