Wolbachia-mediated reproductive manipulation in rice planthoppers

Rice planthoppers, including brown (Nilaparvata lugens), small brown (Laodelphax striatellus), and white-backed (Sogatella furcifera) planthoppers, are major agricultural pests in China and severely affect rice production and food security. The endosymbiotic bacterium Wolbachia is commonly found in these insects, where it regulates reproduction through mechanisms such as cytoplasmic incompatibility (CI) and increased fertility. In this review, we discuss the strain-specific effects of Wolbachia: wLug (in N. lugens, < 50% infection) increases fecundity without CI; wStri (in L. striatellus, 99% infection) induces complete CI and enhances reproduction; and wSfur (in S. furcifera, 90% infection) shows weak or no CI with minimal fecundity effects. Additionally, while wStri can induce CI in N. lugens, its intensity is reduced, suggesting that both the symbiont and the host influence CI strength. The wStri genome contains three copies of the CI factors cifA-cifB, which belong to a newly identified group of genes of unknown function. In L. striatellus, the host protein cytoplasmic aminopeptidase-like protein (CAL) is associated with CI lethality, whereas the NADH quinone oxidoreductase subunit A8 (NDUFA8) may play a role in CI "rescue". Furthermore, Wolbachia enhances rice planthopper reproduction through B vitamin synthesis, the upregulation of vitellogenin (Vg), and the promotion of germ cell division, significantly increasing egg production. These findings shed light on complex Wolbachia-planthopper interactions and their potential for pest control.