Functional analysis of a carboxylesterase gene involved in beta-cypermethrin and phoxim resistance in Plutella xylostella (L.).

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 (PxαE8) in resistance to five insecticides in Plutella xylostella. Results The relative expressions of PxαE8 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 LC25 of beta-cypermethrin, chlorantraniliprole, metaflumizone, phoxim and tebufenozide could induce the specific activity of CarEs and the relative expression of PxαE8 increase, while knockdown of PxαE8 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 PxαE8 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 PxαE8 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.