Endosymbionts are microorganisms living within another organism and are closely associated with their biological functions. Sucking insects viz., aphids, whiteflies, leafhoppers, planthoppers and mealybugs, are major sap-feeding insects that cause considerable damage to crop plants. These homopteran insects have a strong relationship with facultative and obligate bacterial endosymbionts. Through symbiotic adaptations, insects can exploit plant resources and escape from the plant defenses. Endosymbionts play a critical role in physiological adaptation and ecological interactions, greatly affecting host fitness, detoxification processes and interactions with their natural enemies. For example, the endosymbiont Buchnera aphidicola helps the pea aphid, Acyrthosiphon pisum, neutralize hydroxamic acids like DIMBOA derived from plants. It also aids in detoxification processes and improves amino acids metabolism. Beyond detoxification, they also reduce plant defense mechanisms by interfering with communication pathways, triggering susceptibility genes in plants and altering the distribution of nutrients inside host plants. Endosymbionts influence the coevolutionary dynamics between plants and insects as well as the developmental paths of insect host plant ranges, allowing insects to quickly adapt to new plant defenses through the acquisition or change of their symbiont communities. This complex tri-trophic interaction between homopterans, plants and endosymbionts drives the evolution of plant defense and host-plant interaction. The manipulation of these endosymbionts contributes to the development of biological control methods. These modern approaches provide alternatives to established chemical interventions, thus achieving more sustainable and environmentally consistent pest management strategies.
