Frequencies and mechanisms of pesticide resistance in Tetranychus urticae field populations in China.

Abstract

The two-spotted spider mite,\xa0Tetranychus urticae,\xa0is an important agricultural pest worldwide. It is extremely polyphagous and has developed resistance to many pesticides.\xa0Here, we assessed the pesticide resistance of seven field populations of T. urticae in China, their target site mutations, and the activities of their detoxification enzymes. The results showed that abamectin and the traditional pesticides pyridaben, profenofos, and bifenthrin had higher resistance or lower toxicity than more recently developed pesticides including chlorfenapyr, spinetoram, cyflumetofen, cyenopyrafen, bifenazate, and B-azolemiteacrylic. The frequency of point mutations related to abamectin resistance, G314D in the glutamate-gated chloride channel 1 (GluCl1) and G326E in GluCl3, ranged from 47% to 70% and from 0 to 97%, respectively. The frequency of point mutations in A1215D and F1538I of the voltage-gated sodium channel gene (VGSC), which may increase resistance to pyrethroids, ranged from 88% to 100% and from 10% to 100%, respectively. For target sites related to organophosphate resistance, mutation frequencies ranged from 25% to 92% for G119S and from 0 to 23% for A201S in the acetycholinesterase gene (Ace). Mutation G126S in the\xa0bifenazate resistance-related cytochrome b gene (Cytb) was observed in three of the seven T. urticae populations. Higher activities of detoxification enzymes (P450, GST, CarEs, and UGTs) were observed in two T. urticae populations, with significant difference in XY-SX population. These results provide useful information on the status of pesticide resistance of T. urticae in China and suggest that T. urticae field populations may have multiple resistance mechanisms. This article is protected by copyright. All rights reserved.