Susceptibility and Detoxifying Enzyme Activity in Two Spider Mite Species (Acari: Tetranychidae) After Selection with Three Insecticides

Abstract

Changes in the susceptibility and detoxifying enzyme activity were measured in laboratory strains of Banks grass mite, Oligonychus pratensis (Banks), and twospotted spider mite, Tetranychus urticae Koch, that were repeatedly exposed to three insecticides. Three strains of each mite species were exposed to one of two pyrethroids, bifenthrin, and lambda-cyhalothrin, or an organophosphate, dimethoate, for 10 selection cycles at the LC60 for each insecticide. A reference or nonselected strain of each mite species was not exposed to insecticides. After 10 cycles of exposure, susceptibility to the corresponding insecticides, bifenthrin, lambda-cyhalothrin, and dimethoate, decreased 4.5-, 5.9-, and 289.2-fold, respectively, relative to the reference strain in the respective O. pratensis strains, and 14.8-, 5.7-, and 104.7-fold, respectively, relative to the reference strain in the respective T. urticae strains. In the bifenthrin-exposed O. pratensis strain, there was a 88.9-fold cross-resistance to dimethoate. In the dimethoate-exposed T. urticae strain, there was a 15.9-fold cross-resistance to bifenthrin. These results suggest that there may be cross-resistance between dimethoate and bifenthrin. The reduced susceptibility to dimethoate remained stable for three months in the absence of selection pressure in both mites. The decrease in susceptibility in the O. pratensis strains exposed to bifenthrin, lambda-cyhalothrin, and dimethoate was associated with a 4.7-, 3.0-, and 3.6-fold increase in general esterase activity, respectively. The decrease in susceptibility in the T. urticae strains exposed to bifenthrin and lambda-cyhalothrin was associated with a 1.3- and 1.1-fold increase in general esterase activity, respectively. The mean general esterase activity was significantly higher in the pyrethroid-exposed O. pratensis and T. urticae strains than in the nonselected strain. There was no significant increase in esterase activity in the dimethoate-exposed T. urticae strain. The decrease in susceptibility to insecticides was also associated with reduced glutathione S-transferase 1-chloro-2, 4-dinitrobenzene conjugation activity, but this did not appear to be related to changes in insecticide susceptibility. These results suggest that in these mites, the general esterases may play a role in conferring resistance to pyrethroids. However, some other untested mechanism, such as target site insensitivity, must be involved in conferring dimethoate resistance.

Inheritance and detoxification enzyme levels in Tetranychus urticae Koch (Acari: Tetranychidae) strain selected with chlorpyrifos

“…Selection experiments used a modified form of the method developed by Yang et al (2002). At least 400 adult female mites of the SAK strain were transferred into Petri dishes (40 mites/Petri dish) treated with chlorpyrifos concentrations equal to the LC 60 for that cycle.…”

“…Resistance is defined as the development of survival ability by the majority of a normal population when exposed to lethal doses (Ffrench-Constant and Roush 1990). The resistance developed to insecticides can be associated with some specific insect enzymes (Vontas et al 2001;Yang et al 2002;Kim et al 2004;Van Leeuwen et al 2006). The most common types of resistance found in insects are increased enzymatic detoxification and target site insensitivity (Oppenoorth 1984;Scott 1999).…”

Mechanisms of organophosphate resistance in a field population of oriental migratory locust, Locusta migratoria manilensis (Meyen)

“…GST activities were assayed based on the method of Yang et al (2002) with some modifications using CDNB, DCNB, and pNBC as substrates. Briefly, 10 ml of enzyme preparation was mixed with 190 ml of CDNB-GSH solution (10.35 mM GSH: 200 mM CDNB 5 188:2 (v/v)) for CDNB activity analysis.…”

Tetranychus urticae Koch (Acari:Tetranychidae)'nin karanfil popülasyonlarında abamectin ve spirodiclofen'e karşı duyarlılık düzeyleri

“…Esteraz enzim aktivitesi sonuçları incelendiğinde, karanfil seralarından toplanan kırmızıörümcek popülasyonlarının esteraz enzim aktivitelerinin sayısal değerlerinin GSS popülasyonuna göre yüksek bulunduğu görülmektedir. Tetranychus urtica 'de akarisitlere karşı gelişen dirençle esteraz enzim bağlantısını açıklayan birçok çalışma bulunmaktadır (Van Leeuwen & Tirry, 2007;Yang et al, 2002;Mogdaham et al, 2012). Özellikle iki noktalı kırmızıörümcekte abamectin ve spirodiclofen direncinin gelişmesinde esteraz enziminin etkili olduğunu gösteren çalışmalar da mevcuttur.…”