Li_2020_Pest.Manag.Sci_77_2097

BACKGROUND: Carboxylesterases (CarEs) have been acquainted with their detoxification of xenobiotics in organism bodies, including insecticides. Overexpression of CarE genes has been considered playing important roles in insecticide resistance in insects, however it's involvement in multi-insecticide resistance have been rarely reported. This study aimed to assess the function of a CarE gene (PxalphaE8) in resistance to five insecticides in Plutella xylostella. RESULTS: The relative expressions of PxalphaE8 in three multi-insecticide-resistant populations including GD-2017, GD-2019 and HN were 14.8-, 19.5- and 28.0-fold higher than that in the susceptible one. Exposure to LC(25) of beta-cypermethrin, chlorantraniliprole, metaflumizone, phoxim and tebufenozide could induce the specific activity of CarEs and the relative expression of PxalphaE8 increase, while knockdown of PxalphaE8 expression dramatically reduced the activity of CarEs and increased the resistance of P. xylostella (GD-2019) larvae to beta-cypermethrin and phoxim by 47.4% and 45.5%, respectively. Further, a transgenic line of Drosophila melanogaster overexpressing PxalphaE8 was constructed and the bioassay results showed that the tolerance of the transgenic Drosophila to beta-cypermethrin and phoxim were 3.93- and 3.98-fold higher than that of the untransgenic line, respectively. CONCLUSION: These results provided the evidence that overexpression of PxalphaE8 is involved in resistance at least to both beta-cypermethrin and phoxim in multi-insecticide resistant P. xylostella populations, which would help in further understanding the molecular mechanisms of multi-insecticide resistance in this pest. This article is protected by copyright. All rights reserved.