IJMS, Vol. 20, Pages 419: Expressing Double-Stranded RNAs of Insect Hormone-Related Genes Enhances Baculovirus Insecticidal Activity (International Journal of Molecular Sciences)

Baculoviruses have already been used for insect pest control, but the slow killing speed limits their further promotion and application. Here we provide a strategy for improving baculovirus insecticidal activity using Helicoverpa armigera nucleopolyhedrovirus (HearNPV) to express double-stranded RNAs (dsRNAs) targeting cotton bollworm (Helicoverpa armigera) juvenile hormone (JH)-related genes. Droplet-feeding bioassays show that the 50% lethal concentration (LC50) values of recombinant baculoviruses expressing the dsRNA of JH acid methyl transferase gene (HaJHAMT) and the JH acid binding protein gene (HaJHBP) were 1.24 × 104 polyhedral inclusion bodies (PIB)/mL and 2.26 × 104 PIB/mL, respectively. Both were much lower than the control value (8.12 × 104 PIB/mL). Meanwhile, the LT50 of recombinant baculovirus expressing dsRNA of HaJHBP was only 54.2% of the control value, which means that larval death was accelerated. Furthermore, the mRNA level of target genes was reduced in recombinant baculovirus-treated cotton bollworm larvae. Transcription of several key genes involved in hormone signaling pathways--for example, ecdysone receptor gene (HaEcR)--was also altered. This study establishes a new strategy for pest management by interfering with insect hormone-related gene expression via baculoviruses, and the engineered baculoviruses have great potential application in cotton production.