Gut microbiota profiles as potential indicators of irradiation-induced quality loss in mass-reared Aedes albopictus males.

Aim: The Sterile Insect Technique is a promising method for Aedes albopictus control, but its effectiveness hinges on male quality, which may be compromised during mass-rearing and irradiation. Reliable biological indicators capable of reflecting irradiation-induced quality loss remain limited. Gut microbiota regulates mosquito development, immunity, and metabolism and may therefore provide potential indicators of sterile male quality. This study explored whether gut microbiota composition can reflect irradiation-induced quality impairment in males of a long-term (over 3 years) mass-reared Ae. albopictus GT strain. Methods: Male pupae were exposed to X-ray irradiation without filtration at an estimated absorbed dose of 78 Gy. Emergence rate, flight ability, longevity, metabolic capacity, and gut microbiota (via 16S rRNA gene sequencing, culture-based methods, and qPCR) were compared between irradiated and non-irradiated males. Results: Irradiation significantly reduced emergence rate, flight ability, and longevity. It did not alter gut microbiota diversity, but reshaped its composition, including the emergence of Sphingobacterium, increased abundance of Stenotrophomonas and Comamonas, and decreased levels of Delftia and Achromobacter. Similarity was observed in the culturable gut bacterial community, confirmed by qPCR with eight selected key taxa. Metabolic changes included reduced glutamine synthetase activity and elevated glucose levels in irradiated males. Conclusion: These results show that irradiation-induced quality loss is accompanied by reproducible shifts in gut microbiota composition and metabolic status. These findings suggest that gut microbiota profiles may serve as potential indicators of irradiation-associated quality changes in sterile males and provide preliminary evidence for microbiota-informed quality assessment approaches in Ae. albopictus SIT programs.