Abstract
Insect-associated microorganisms profoundly influence host nutrition, development, reproduction, ecological adaptation, and responses to management interventions. However, the microbial partners associated with insects are not functionally or spatially uniform, and the terms
endosymbionts
,
gut microbiota
, and
symbiotic microorganisms
should not be treated as interchangeable. In this review, we distinguish obligate intracellular endosymbionts, facultative endosymbionts, and transient or environmentally acquired gut microbiota, and examine how these different microbial associates contribute to insect pest success and vulnerability. Across insect taxa, microbial partners are involved in nutrient provisioning, detoxification of plant allelochemicals and insecticides, immune modulation, reproductive manipulation, and host plant use. These functions have generated growing interest in symbiont-informed pest management strategies, including microbiome disruption, symbiont-targeted suppression, incompatible insect technique, paratransgenesis, and symbiont-mediated RNA interference. At the same time, translational enthusiasm must be balanced by recognition of ecological uncertainty, variable field performance, host–symbiont context dependence, regulatory complexity, and biosafety concerns, particularly for genetically modified symbiont-based systems. Drawing on published case studies, this review highlights both promising outcomes and contradictory findings, emphasizing that symbiont effects are not universally beneficial or predictable from the standpoint of pest control. We argue that future progress depends on greater conceptual clarity, stronger comparative synthesis across studies, and rigorous evaluation of deployment risks under realistic agroecosystem conditions. A more critical and ecologically grounded understanding of insect–microbe associations will be essential if symbiont-based interventions are to become credible components of sustainable insect pest management.