Insects are widely distributed across the globe and exhibit strong adaptability in diverse living environments, a capability closely linked to the diversity of their gut microbiota. The composition of insect gut bacteria varies with species, living environment, diet, and development stage. In recent years, the widespread application of culture-independent strategies based on molecular biology techniques has provided substantial information for studies on the interaction mechanisms between insects and their gut microbiota. However, culture-dependent strategies aimed at isolating pure cultures remain indispensable. Only by integrating multi-techniques such as bacterial isolation and pure culture, axenic insect technology, and molecular biology can in-depth research be conducted on key gut bacteria of insects. This review summarizes culture-dependent and -independent strategies used for the analysis of the diversity and functions of insect gut microbiota, focusing on the traditional methods and new strategies for microbial cultivation, multi-omics techniques, and axenic insect technology. Recent studies showed that the application of integrated techniques is powerful for illustrating the microbial function and evolution of gut microbiota, and the interactions between intestinal bacteria and their hosts. Studies have shown that the insect gut microbiota plays important roles in the promotion of host growth and development by regulating host metabolic pathways, contributing to host nutrition, and supporting the host in defending against pathogens or degrading toxic compounds. Future research directions and strategies are also proposed, providing insights into further exploration of the interaction mechanisms between symbiotic insect gut bacteria and their hosts, as well as future applications in various fields.
Li et al. (Mon,) studied this question.