A distinct strain of Arsenophonus symbiont decreases insecticide resistance in its insect host

Symbiotic bacteriaare important drivers of phenotypic diversity in insects. One of the widespread symbionts to have emerged belongs to the genus Arsenophonus, however, its biological functions in most host insects remain entirely unknown. Here we report two distinct Arsenophonusstrains in the brown planthopper(BPH), Nilaparvata lugens, a major pest insect in Asian countries that causes significant economic damage through rice crop destruction. Genomic resequencing data suggested that one Arsenophonusstrain (S-type) negatively affected the insecticide resistance of the host. Indeed, replacement of the resident Arsenophonuswith the S-type Arsenophonussignificantly decreased host insecticide resistance. Transcriptome and metabolome analysis revealed down-regulation of xenobiotic metabolism and increased amino acid accumulation in the S-type Arsenophonusinfected host. This study demonstrates how a symbiont-mediated phenotypic change can occur. The results of this study will aid in developing strategies that work through imposing an ecological disadvantage on insect pests, which will be of great value for pest controlin agricultural industry.