Antibiotic-induced gut microbiota perturbation is associated with impaired fitness and reduced starvation tolerance in the invasive pest Hyphantria cunea.

Hyphantria cunea is a destructive invasive pest that poses severe threats to forest ecosystems and agroforestry economies globally, yet research on the functional roles of its gut microbiota remains limited. In this study, fourth-instar larvae were treated with a five-antibiotic cocktail incorporated into artificial diets to perturb gut bacterial communities and to examine how these changes relate to host physiology. Our results showed that antibiotic treatment significantly impaired larval fitness, characterized by reduced body weight, prolonged developmental duration, decreased pupation and emergence rates, and shortened survival time under starvation stress. It is noteworthy that the larvae showed no overt lethal phenotypes or reduced food consumption. 16S rRNA amplicon sequencing revealed a marked shift in the gut microbiota structure, with the dominant genus Enterococcus dropping from 75.10% to 0.21%, accompanied by a substantial increase in Acinetobacter abundance. Following antibiotic treatment, PICRUSt2-based functional prediction further suggested potential declines in KEGG pathways related to the ABC transporter system and carbohydrate metabolism. Correspondingly, hemolymph protein, glucose, and triglyceride contents were significantly reduced following antibiotic exposure. Collectively, these findings suggest that antibiotic-induced gut microbiota perturbation, especially the depletion of dominant bacteria, is associated with altered growth, development, and starvation tolerance of H. cunea. This study may provide a theoretical reference for developing novel control strategies that target gut bacteria in this invasive pest.