Citrus‐mediated gene silencing of cytochrome P450 suppresses insecticide resistance and increases mortality in Diaphorina citri

Abstract

AbstractBACKGROUNDAsian citrus psyllid, Diaphorina citri, is a hemipteran that vectors the causal pathogen of citrus greening disease, or huanglongbing (HLB). HLB is a tree killing disease that has severely limited citrus production globally. Unfortunately, there is no cure for this disease, and mitigation depends on multiple insecticide applications to reduce vector populations. Silencing of cytochrome P450 expression associated with detoxification enzymes by RNA interference is known to increase susceptibility of D. citri to insecticides. However, dsRNA was previously introduced into psyllids by topical applications. The possible application of this technology for pest management will require effective field delivery of the dsRNA. Therefore, we evaluated a virus vector (Citrus tristeza virus; ‘mild strain’ T36) to deliver gene silencing directly to this sap‐sucking insect via plant phloem. Citrus macrophylla plants inoculated with CTV expressing a truncated consensus sequence of CYP450 (CTV‐tCYP450) constantly produced small interfering RNA in the plant phloem that targeted five cytochrome p540 (CYP450) genes in D. citri.RESULTSInsecticide susceptible D. citri reared on citrus infected with CTV‐tCYP450 were subsequently more susceptible to imidacloprid, fenpropathrin, carbaryl, and chlorpyrifos than those reared on citrus infected with wildtype CTV or non‐infected negative controls. Additionally, nymph survival and adult lifespan were significantly reduced when psyllids were reared on CTV‐tCYP450 citrus plants compared with controls. Interestingly, similar results were obtained after one and two generations of rearing. Finally, field‐collected psyllids from areas with known broad‐spectrum insecticide resistance were rendered more susceptible to imidacloprid and fenpropathrin after feeding on CTV‐tCYP450 citrus trees as compared with those reared on controls.CONCLUSIONThe integration of citrus‐mediated RNA inference targeting psyllid detoxification enzymes could function as a resistance management tool and reduce insecticide input in an integrated pest management program for HLB. © 2024 Society of Chemical Industry.