Effects of Host Tea Cultivars on Adaptability and Gut Microbiota of Ectropis grisescens Warren

This study aimed to explore the effects of different host tea cultivars on population fitness, as well as the abundance and diversity of gut bacteria of Ectropis grisescens Warren. The feeding preference, survival rate, body length and body weight of E. grisescens larvae were determined on six tea cultivars. Furthermore, 16S rRNA high-throughput sequencing technology was adopted to analyze the community structure and diversity of gut bacteria in larvae fed on Camellia sinensis cv. ‘Xinyang 10’, Camellia sinensis cv. ‘Fudingdabaicha’ and Camellia sinensis cv. ‘Wuniuzao’, and correlation analysis was performed between gut bacterial data and larval growth-development indices. The results revealed significant differences in feeding preference and adaptability of E. grisescens larvae across different tea cultivars. Larvae feeding on C. sinensis cv. ‘Xinyang 10’ achieved the highest survival rate, body length and body weight, showing the optimal fitness; larvae fed on C. sinensis cv. ‘Wuniuzao’ exhibited the lowest values for all measured indices and the poorest fitness. Gut microbiota analysis indicated that Proteobacteria and Firmicutes constituted the core bacterial taxa, yet their relative abundances differed significantly among host treatments. Serratia marcescens was the core gut bacterium in larvae feeding on C. sinensis cv. ‘Xinyang 10’ and C. sinensis cv. ‘Wuniuzao’, whereas Enterococcus flavescens ATCC 49996 dominated the gut of larvae reared on C. sinensis cv. ‘Fudingdabaicha’. Functional profiles demonstrated that gut bacteria of larvae were mainly involved in carbon metabolism, amino acid metabolism, membrane transport, energy metabolism and other pathways. Correlation analysis showed that larval growth-development indices were positively correlated with Serratia marcescens. Collectively, host tea cultivars shape the adaptability of E. grisescens, and the underlying mechanism is potentially associated with the composition, abundance and function of gut bacteria. This research provides a theoretical foundation for deciphering the interaction mechanism between tea pests and their hosts from the perspective of gut bacteria and developing novel pest-management strategies.