Insects as a New Source of Plant Growth Promoting Bacteria - Review.

The intensification of agriculture, including excessive use of fertilizers and pesticides, has reduced soil fertility and harmed biodiversity. Thus, interest in sustainable alternatives such as plant growth promoting bacteria (PGPB) is growing. These microbes aid plants via nitrogen fixation, phosphate solubilization, phytohormone production, and pathogen suppression. Most PGPB come from soil and plant tissues, but insect-associated bacteria remain a largely unexplored reservoir. Insects harbor diverse microbial communities inhabiting their guts and cuticle surfaces. Due to their varied diets and broad ecological distribution, insects may serve as reservoirs for bacterial strains with unique functional traits. This review summarizes the current state of knowledge regarding insect-derived PGPB, focusing on their ecological roles, functional capabilities, and potential applications in agriculture. Key aspects addressed include microbial diversity in insects, mechanisms of plant growth promotion, insect–microbe–plant interactions, and methodological approaches for the isolation and characterization of these bacteria. Several studies are highlighted to illustrate successful applications of insect-associated PGPB in improving plant health and disease resistance. Although this research area remains in its early stages, it holds considerable potential for the development of novel biopesticides and biofertilizers. By integrating microbiological, entomological, and agricultural perspectives, insect-derived PGPB may contribute to the advancement of more sustainable and resilient farming systems. This review aims to underscore the importance of expanding the search for effective PGPB to include insect microbiomes and to encourage further research in this promising field.