Susceptibility to Acaricides and the Frequencies of Point Mutations in Etoxazole- and Pyridaben-Resistant Strains and Field Populations of the Two-Spotted Spider Mite, Tetranychus urticae (Acari: Tetranychidae)

Abstract

The two-spotted spider mite Tetranychus urticae Koch is a major agricultural pest worldwide and is known to rapidly develop resistance to pesticides. In the present study, we explored a field strain that was collected in 2000 and 2003 and has been exhibiting resistance to etoxazole and pyridaben over the last 16 years. The resistance ratios of the etoxazole- and pyridaben-resistant strains (ER and PR) to etoxazole or pyridaben were more than 5,000,000- and 4109.6-fold higher than that of the susceptible strain, respectively. All field-collected populations showed resistance to etoxazole and pyridaben. The ER and PR strains showed cross-resistance to several acaricides. Both I1017F and H92R point mutations were detected in 7 out of 8 field groups. Spirodiclofen and spiromesifen resulted in more than 77.5% mortality in the 8 field groups. In addition, the genotype frequency of the I1017F point mutation was 100.0% in the ER strain, and that of the H92R point mutation was 97.0% in the PR strain. All of the field populations were found to have a high frequency of I1017F. These results suggest that the observation of resistance patterns will help in designing a sustainable IPM program for T. urticae.

Resistance of Panonychus citri (McGregor) (Acari: Tetranychidae) to pyridaben in China: monitoring and fitness costs

“…2 The resistance ratio (RR) of a pyridaben-resistant strain of the two-spotted spider mite (Tetranychus urticae Koch) was more than 4109.6-fold higher than that of the susceptible strain. 5 Fitness costs in resistant individuals can be related to the reallocation of resources and energy to resistance-enhancing traits. 6 Biological trait changes resulting from resistance include fecundity, survival rate, development time, and percentage egg hatch.…”

A mutation in chitin synthase I associated with etoxazole resistance in the citrus red mite Panonychus citri (Acari: Tetranychidae) and its uneven geographical distribution in Japan

“…The amino acid substitution I1017F in helix 5 in clusters of five transmembrane segments (5TMS) in CHS1 is a major resistance factor to the mite growth inhibitors etoxazole, hexythiazox and clofentezine 8–11 . This mutation has been reported in field and laboratory T. urticae populations globally: Japan, South Korea, Europe, Africa, Australia and the United States 8,12–19 . The I1017F substitution confers a high level of etoxazole resistance (LC 50 > 1000 mg L −1 ) 8 .…”

“…[8][9][10][11] This mutation has been reported in field and laboratory T. urticae populations globally: Japan, South Korea, Europe, Africa, Australia and the United States. 8,[12][13][14][15][16][17][18][19] The I1017F substitution confers a high level of etoxazole resistance (LC 50 > 1000 mg L −1 ). 8 Inheritance of etoxazole resistance is completely recessive in T. urticae.…”

“…8,20,21 Thus, toxicological experiments on field populations have frequently shown low or moderate resistance 15,17,22 other than the case that mostly fixed to I1017F. 13,19,23 The citrus red mite Panonychus citri (McGregor) (Acari: Tetranychidae) is a major mite pest in citrus groves. It is distributed worldwide and attacks deciduous fruit trees and ornamental trees as well as citrus trees.…”

“…Inheritance of etoxazole resistance is completely recessive in T. urticae 8,20,21 . Thus, toxicological experiments on field populations have frequently shown low or moderate resistance 15,17,22 other than the case that mostly fixed to I1017F 13,19,23 …”