The bacterial endosymbionts occur in a diverse array of insect species and are usually rely within the vertical transmission from mothers to offspring. In addition to primary symbionts, plant sap-sucking insects may also harbor several diverse secondary symbionts. Bacterial symbionts play a prominent role in insect nutritional ecology by aiding in digestion of food or supplementing nutrients that insect hosts can't obtain sufficient amounts from a restricted diet of plant phloem. Currently, several other ecologically relevant traits mediated by endosymbionts are being investigated, including defense toward pathogens and parasites, adaption to environment, influences on insect-plant interactions, and impact of population dynamics. Here, we review recent theoretical predictions and experimental observations of these traits mediated by endosymbionts and suggest that clarifying the roles of symbiotic microbes may be important to offer insights for ameliorating pest invasiveness or impact.
Keywords: adaption; behavior; defense; endosymbiont; multilevel selection; mutualism.