Biochemical mechanisms of insecticide resistance in the diamondback moth (DBM), Plutella xylostella L. (Lepidopterata: Yponomeutidae), in the Sydney region, Australia

Abstract

Following the detection of resistant diamondback moth (DBM) populations to synthetic pyrethroid, organophosphorus and indoxacarb insecticides in the Sydney Basin, a study of the major biochemical mechanisms was conducted to determine the type of resistance in these populations. The activity of cytochrome P450 monooxygenases increased two-to sixfold when compared with the susceptible strain. Up to a 1.9-fold increase in esterase activity in resistant strains compared with the susceptible strain was observed. In vitro inhibition studies showed that profenofos, methamidophos and chlorpyrifos strongly inhibited the esterases while permethrin and esfenvalerate resulted in less than 30% inhibition. Qualitative analysis of the esterases using native polyacrylamide gel electrophoresis showed four bands in both the susceptible and resistant individuals with more intense staining in the resistant individuals. The development of these bands was inhibited by methamidophos and chlorpyrifos pretreatment of the protein extract while permethrin and esfenvalerate did not exhibit this effect. Glutathione S-transferase (GST) activity was significantly higher in two field populations compared with the remaining populations. Overall, the study showed that the mechanisms of insecticide resistance in the DBM populations in the area studied were due to cytochrome P450 monooxygenases, esterase and GSTs, and possibly other non-metabolic mechanisms that were not investigated in the present study.

Identification and characterisation of multiple glutathione S‐transferase genes from the diamondback moth, Plutella xylostella

“…8 DBM resistance to acephate, indoxacarb, beta-cypermethrin and spinosad has been reported. 13,16,52,53 In this work, these insecticides were used to challenge the expression of DBM GST genes.…”

Induction and Transmission of Tolerance to the Synthetic Pesticide Emamectin Benzoate in Field and Laboratory Populations of Diamondback Moth

“…Metabolic capacity is strongly related to the activities of the enzymes carboxylesterase (CarE), glutathione S-transferase (GST) Kao and Sun 1991), and cytochrome P450 monooxygenases (MFO) (Li et al 2007;Eziah et al 2009). Insensitivity of the target site to organophosphates and pyrethroids is usually related to the activity of acetylcholine esterase (AChE) (Baek et al 2005;Lee et al 2007).…”

Temperature, deltamethrin‐resistance status and performance measures of Plutella xylostella: complex responses of insects to environmental variables

“…Field‐evolved pyrethroid‐resistance in DBM collected from 16 field sites in southern Australia was related to at least three different mutations (L1014F, T929I and F1020S) in the para sodium channel gene (Endersby et al ., ). Metabolic mechanisms of pyrethroid resistance, which may involve detoxification by the microsomal P450‐dependent monooxygenase system, esterases or glutathione S‐transferases, have also been reported in DBM (Sun et al ., ; Eziah et al ., ). It is possible that the resistance in any one individual comprises more than one mechanism (Schuler et al ., ; Lambkin & Furlong, ).…”