Gut Bacteria Strategies of Hylurgus ligniperda F. (Coleoptera Scolytidae) in Adapting to Temperature Changes

Insect establishment and dispersal are often influenced by temperature, with gut microbiota playing a critical role in host adaptation to environmental stress. This study investigated how gut bacterial structure and function in the invasive red-haired bark beetle (RHB), <i>Hylurgus ligniperda</i> (Fabricius) respond to temperature fluctuations, focusing on three core culturable bacteria: <i>Rahnella perminowiae</i>, <i>Serratia marcescens</i>, and <i>Hafnia psychrotolerans</i>. We found that temperature variations induced specific structural changes in the gut bacterial community, which in turn affected key functional processes such as carbohydrate metabolism. Notably, the relative abundance of <i>Rahnella</i> increased by more than 10% during the cold period (CP), and it maintained stable production of proteases and lipases under low temperatures-a trait that may be crucial for supporting host development in cold environments. Feeding on the diet converted by <i>R. perminowiae</i> at 5 °C resulted in a 20.9-day reduction in pupation time and a 1.8-fold increase in adult body mass compared to the blank control group, respectively. We propose that temperature remodels the gut microbiota by modulating competitive relationships among functional bacteria. This regulatory mechanism, based on functional redundancy and dynamic balance, serves as a buffer strategy that aids insect adaptation to temperature changes. Our findings provide new insights and a theoretical foundation for understanding pest outbreak patterns under climate warming and developing microbe-targeted control strategies.