Dual-effect recombinant baculovirus mediated RNA interference with V-ATPase of fall armyworm, Spodoptera frugiperda

The fall armyworm (FAW, Spodoptera frugiperda ), has rapidly spread from American continent to many other areas and caused serious damage to local agriculture. In order to explore a more environment-friendly and effective control strategy against this pest, we developed a dual-effect RNAi system based on baculoviruses infection and gene silencing. V-ATPase subunits A and B of FAW ( Sf vATPaseA and Sf vATPaseB) were cloned for the construction of recombinant baculoviruses (rBviruses) of Bacmid-ds Sf vATPaseA and Bacmid-ds Sf vATPaseB with the capacity of producing small interfering RNA. The efficacy of baculovirus-mediated RNAi was evaluated by injection delivery. The results showed that the relative expression levels of Sf vATPaseA and Sf vATPaseB were significantly suppressed by constructed rBviruses with reduction rates of 73.85% and 69.82%. The larval inhibition rates of the body weight and length resulting from RNAi were more than 82% and 40%, respectively. More importantly, these two rBviruses greatly accelerated the larval death of FAW with a total mortality using two days less than that caused by bacmid control. After ten serial passages, both rBviruses exhibited excellent genetic stabilities. These results suggest that the creation of dual-effect biopesticides with both activities of viral infection and gene silencing is feasible and prospective.