Overexpression of PxαE14 Contributing to Detoxification of Multiple Insecticides in Plutella xylostella (L.)

The diamondback moth, Plutella xylostella (L.), has evolved with varying degrees of resistance to almost all major classes of insecticides and has become the most resistant pest worldwide. The multiresistance to different types of insecticides has been frequently reported in P. xylostella, but little is known about the mechanism. In this study, a carboxylesterase (CarE) gene, Px alpha E14, was found significantly overexpressed in a field-evolved multiresistant P. xylostella population and can be dramatically induced by eight of nine tested insecticides. Results of the real-time quantitative polymerase chain reaction (RT-qPCR) showed that Px alpha E14 was predominantly expressed in the midgut and malpighian tubule of larvae. Knockdown of Px alpha E14 dramatically increased the susceptibility of the larvae to beta-cypermethrin, bifenthrin, chlorpyrifos, fenvalerate, malathion, and phoxim, while overexpression of Px alpha E14 in Drosophila melanogaster increased the tolerance of the fruit flies to these insecticides obviously. More importantly, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay showed that the recombinant Px alpha E14 expressed in Escherichia coli exhibited metabolic activity against the six insecticides. The homology modeling, molecular docking, and molecular dynamics simulation analyses showed that these six insecticides could stably bind to Px alpha E14. Taken together, these results demonstrate that constitutive and inductive overexpression of Px alpha E14 contributes to detoxification of multiple insecticides involved in multiresistance in P. xylostella. Our findings provide evidence for understanding the molecular mechanisms underlying the multiresistance in insect pests.

Automated summary

In this study, a carboxylesterase gene, Px alpha E14, was found to be significantly overexpressed in a field-evolved multiresistant population of the diamondback moth, Plutella xylostella. Px alpha E14 was predominantly expressed in the midgut and malpighian tubule of larvae. Knockdown of Px alpha E14 increased the susceptibility of the larvae to multiple insecticides, while overexpression of Px alpha E14 in fruit flies increased their tolerance to these insecticides. Recombinant Px alpha E14 expressed in Escherichia coli exhibited metabolic activity against multiple insecticides. These findings contribute to our understanding of the molecular mechanisms underlying multiresistance in insect pests.