The role of pest-associated microbes in insect-plant interactions

Pest insects pose a major threat to global food security and climate change is currently driving their accelerated expansion. The Southern green shield bug, Nezara viridula, is an invasive pest that feeds on important food crops and is threatening global food production. Current chemical control methods are ineffective and harmful to the environment and non-target organisms, emphasizing the importance of developing alternative pest control strategies. Since insects are known to live in a close relationship with beneficial microorganisms, we study microbes associated with pest insect N. viridula and their effect on plant defenses. Using 16S rRNA amplicon sequencing, metagenome studies, fluorescent in situ hybridization and confocal microscopy, we found that the insect’s microbiome consists of a core set of microbial genera including Pantoea, Sodalis, Serratia, Klebsiella and Commensalibacter, which are located in different organs. During feeding these microbes are transmitted to the plant where they suppress plant defense pathways and degrade toxic plant metabolites, likely benefiting their insect host. Specifically targeting these microbes or preventing their suppressive effect on plant defense signaling and subsequent toxin production might be the next step in the development of  sustainable pest control.