Super-kdr mutation M918L and multiple cytochrome P450s associated with the resistance of Rhopalosiphum padi to...

Rhopalosiphum padi is an important pest affecting cereal crops worldwide. Pyrethroid, including lambda-cyhalothrin, has been widely used to control R. padi in the field. This work investigated the resistance levels of R. padi field populations to lambda-cyhalothrin, and analysed biochemical and molecular mechanisms of aphid resistance to the insecticide pyrethroid.

A lambda-cyhalothrin-resistant field population (JY) was sampled, and a super-kdr mutation, M918L, in the voltage-gated sodium channel (VGSC) was identified in the population. The lambda-cyhalothrin-resistant strain (LC-R) was subsequently established by selecting the field population with lambda-cyhalothrin. All individuals of the R. padi LC-R strain showed the M918L heterozygous mutation in the VGSC IIS4-IIS6 region. Cross-resistance profiles of the LC-R strain to nine insecticides were detected. Both synergistic and enzyme activity studies indicated that cytochrome P450 monooxygenase played an important role in this resistance. Further gene expression analysis showed that seven P450 genes were significantly upregulated in the LC-R strain compared with the susceptible strain.

Field-evolved resistance to pyrethroid insecticides has been found in R. padi. The M918L (super-kdr) mutation in the VGSC was documented for the first time in field samples obtained from an important wheat-growing area. The super-kdr mutation, as well as metabolic resistance mediated by P450 genes, was determined to contribute to the lambda-cyhalothrin resistance in R. padi. © 2020 Society of Chemical Industry.