The guts of insect pests are typical habitats for microbial colonization and the presence of bacterial species inside the gut confers several potential advantages to the insects. These gut bacteria are located symbiotically inside the digestive tracts of insects and help in food digestion, phytotoxin breakdown, and pesticide detoxification. Different shapes and chemical assets of insect gastrointestinal tracts have a significant impact on the structure and makeup of the microbial population. The number of microbial communities inside the gastrointestinal system differs owing to the varying shape and chemical composition of digestive tracts. Due to their short generation times and rapid evolutionary rates, insect gut bacteria can develop numerous metabolic pathways and can adapt to diverse ecological niches. In addition, despite hindering insecticide management programs, they still have several biotechnological uses, including industrial, clinical, and environmental uses. This review discusses the prevalent bacterial species associated with insect guts, their mode of symbiotic interaction, their role in insecticide resistance, and various other biological significance, along with knowledge gaps and future perspectives. The practical consequences of the gut microbiome and its interaction with the insect host may lead to encountering the mechanisms behind the evolution of pesticide resistance in insects.

This study investigates the effect of a brand-new tank-mix adjuvant, Spray Adjuvant—Paraffinic Hydrocarbon Surfactant Complex (SA-PHSC), in enhancing the efficacy of commonly used insecticides and acaricides against two significant pests of tea plantations, the black looper (Hyposidra talaca) and the red spider mite (Oligonychus coffeae). Given the pest’s major influence on tea cultivation, which can result in output reductions of up to 55%, this study addresses mounting concerns of pesticide resistance and climate change. Laboratory bioassays showed that the combination of SA-PHSC with the insecticides quinalphos, deltamethrin, and emamectin benzoate, and acaricides etoxazole and fenpyroximate, significantly increased the mortality rates of H. talaca larvae (76.67–100.0%) and O. coffeae adults (100.0%). Additionally, enhancements were noted in the mechanisms of pest cuticular penetration and contact toxicity. These observations were corroborated by field trials, which demonstrated enhanced control of H. talaca (70.47–97.63%) and O. coffeae (75.87–96.59% reduction) populations, as well as increased green tea leaf yields, as a result of SA-PHSC treatment in conjunction with the evaluated pesticides. In addition, the study evaluated the phytotoxicity and organoleptic attributes of the made tea after application, confirming the safety and absence of any off-flavors in the final product (scoring 6.6–7.0). These findings indicate that SA-PHSC could serve as a valuable adjuvant for sustainable pest management in tea cultivation, as it has the ability to optimize the application of currently recommended insecticides and acaricides and restore pest susceptibility.