Pesticide-utilizing bacterial strains- Priestia flexa and Bacillus safensis isolated from the gut of tea looper, Biston suppressaria (Lepidoptera: Geometridae): A major pest of tea plant

Pesticide resistance has emerged as a critical challenge in modern agriculture, including tea plantations. Previous studies have highlighted the vital role of gut bacteria in developing resistance, offering potential opportunities for integrating novel bacterial strains into pest management strategies. Biston suppressaria poses a significant threat to the tea industry in India. The frequent application of flubendiamide for its control has resulted in increased resistance. Therefore, this study aims to investigate the gut bacteria of this pest that may confer resistance against pesticides and tea allelochemicals, while proving nutritional benefits to the host. Six flubendiamide-tolerant gut bacteria have been isolated through in vitro analysis. Among them, Priestia flexa (DM1a) and Bacillus safensis (DM2) showed high flubendiamide tolerance and cross-tolerance to deltamethrin, quinalphos, and emamectin benzoate. Additionally, a pesticide utilization assay conducted on MSF media revealed their ability to utilize pesticides for growth and development, indicating pesticide detoxification through the degradation process. The cellulose degradation and caffeine utilization tests confirmed their nutritional benefits and protection from tea allelochemicals. Furthermore, the strains exhibited tolerance to toxic metals such as Cd, Pb, As, and Cr up to 2500 ppm and resistance to certain antibiotics with an MDR index of ≥ 0.2. This result underscores the chances of spreading these resistance genes to the host pest and also the risk of disseminating to the surrounding environment, raising concerns. Moreover, GC-MS analysis of the gut extract reveals an abundance of fatty acids derivatives, indicating metabolic resistance in this pest. Overall, this study enhances the understanding of the potent gut bacteria associated with this major tea pest and suggests that these gut bacteria are not merely inhabitants but significant contributors to the host’s survivability and fitness, which must be considered when formulating pest management strategies.