Susceptibility and potential biochemical mechanism of Oedaleus asiaticus to beta-cypermethrin and deltamethrin in the Inner Mongolia, China

• Five field populations of O. asiaticus showed different susceptibility to beta-cypermethrin and deltamethrin.
• Enzyme activities of CarEs and GSTs were consistent with the susceptibility to pyrethroid.
• mRNA expression of CarEs or GSTs was largely positively correlated with the susceptibility to pyrethroid.
• Enzyme activities and mRNA expression of CarEs or GSTs may contribute to the susceptibility differences.

Oedaleus asiaticus is a highly destructive grass pest in Inner Mongolia, China, and likely developed resistance to pyrethroid insecticides due to their frequent application for control of this locust. In this study, the susceptibility of five field populations of O. asiaticus to two pyrethroid insecticides was investigated. The Wulate Middle Banner (WB) population was the least susceptible, whereas the Ewenki Banner (EB) population appeared to be the most sensitive. The WB population was 3.16 and 5.15-fold less sensitive to beta-cypermethrin and deltamethrin than EB population, respectively. Further, the enzyme activities and mRNA expression levels of carboxylesterase (CarE) and glutathione-S-transferase (GST) were determined and we found that their activities in the WB population were 5.15 and 2.8-fold higher than those in the EB population, respectively. Quantitative real-time PCR (qRT-PCR) analysis demonstrated that the mRNA expression levels of CarE and GST genes were positively correlated with the LD50 in the WB, Siziwang Banner (SB) and EB populations. Our findings suggest that differences in susceptibility to pyrethroids in O. asiaticus might be attributed to the elevated activities and mRNA expression levels of CarE and GST genes.

Differences in susceptibility of O. asiaticus populations from five areas of Inner Mongolia steppes to two pyrethroids were detected. The activities of the CarE and GST enzymes and mRNA expression levels were positively correlated with variation in susceptibility.Figure optionsDownload as PowerPoint slide