RNAi-targeted silencing of OdfoCYP301A1 and OdfoGSTo1 increased the susceptibility of Odontotermes formosanus (Blattodea: Termitidae) to the nonsteroidal ecdysone agonist RH-5849

Odontotermes formosanus (Blattodea: Termitidae) is a social insect that significantly damages horticultural trees and water conservation infrastructure. Our previous studies confirmed that 1,2-dibenzoyl-1-tert-butylhydrazine (RH-5849) is toxic to O. -formosanus. However, insects have detoxification enzymes like cytochrome P450 (CYP) and glutathione S-transferase (GSTs) that can detoxify insecticides and mitigate their toxicity. To investigate CYP and GSTs in the defense of O. formosanus against RH-5849, we assessed the effects of the CYP inhibitor piperonyl butoxide and the GSTs inhibitor diethyl maleate on the toxicity of RH-5849 against O. formosanus. The results indicated that piperonyl butoxide and diethyl maleate significantly increased the lethality of RH-5849 to O. formosanus by 49.61% and 37.21%, respectively. Through RNA-seq and quantitative real-time PCR, OdfoCYP301A1 and OdfoGSTo1 were identified, with relative expression levels of 2.90 and 11.91, respectively. Moreover, we cloned OdfoCYP301A1 and OdfoGSTo1 and synthesized double-stranded RNA (dsRNA) based on these sequences. Furthermore, we evaluated the lethality of RH-5849 to O. formosanus following 24 h of dsRNA interference treatment. The results indicated a significant increase in the lethality of RH-5849 to O. formosanus following interference with OdfoCYP301A1 or OdfoGSTo1. These results suggest that OdfoCYP301A1 and OdfoGSTo1 play important roles in the defense of O. formosanus against RH-5849. Furthermore, this study provides new targets for the combined use of dsRNA and RH-5849 in the control of O. formosanus.