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Comparative acaricide susceptibility and detoxifying enzyme activities in field‐collected resistant and susceptible strains of Tetranychus urticae
Author(s) -
Van Leeuwen Thomas,
Van Pottelberge Steven,
Tirry Luc
Publication year - 2005
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.1001
Subject(s) - tetranychus urticae , acaricide , biology , acariformes , toxicology , insecticide resistance , enzyme , microbiology and biotechnology , acari , botany , biochemistry
Abstract A field‐collected strain (MR‐VL) of the two‐spotted spider mite, Tetranychus urticae Koch, exhibited strong resistance to bifenthrin, dicofol and fenbutatin oxide in comparison with a susceptible laboratory strain (LS‐VL). The MR‐VL strain was screened for cross‐resistance with several currently used acaricides. Cross‐resistance was detected with clofentezine (RR = 2631), dimethoate (RR = 250), chlorfenapyr (RR = 154), bromopropylate (RR = 25), amitraz (RR = 17), flucycloxuron (RR = 15) and azocyclotin (RR = 7). Abamectin, acequinocyl, bifenazate, tebufenpyrad and spirodiclofen did not show any signs of cross‐resistance. Enhanced detoxification by increased activity of mono‐oxygenases (MO) and esterases is at least partially responsible for the observed resistance and cross‐resistance. MO assays with 7‐ethoxycoumarin (7‐EC) were optimised and 7‐ethoxy‐4‐trifluoromethylcoumarin (7‐EFC), a new MO‐substrate, was evaluated for the first time in T urticae and proved to be a good alternative to 7‐EC. Approximately 3‐ and 4‐fold higher MO activity was detected with 7‐EFC and 7‐EC respectively in the MR‐VL strain. Kinetic parameters of general esterase assays with 4‐nitrophenyl acetate and 1‐naphthyl acetate as substrate indicated that more esterases were present in the MR‐VL strain. A first attempt was made to classify the esterases present in T urticae . Acetyl‐, aryl‐ and carboxyl‐esterases were detected with the use of inhibitors after separation by native PAGE. Glutathione‐ S ‐transferases did not seem to play any role in the observed resistance and no differences were detected when the general oxidative capacities of the two strains were compared. Copyright © 2005 Society of Chemical Industry