Esterase-mediated bifenthrin resistance in a multiresistant strain of the two-spotted spider mite, Tetranychus urticae |
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Authors: | Van Leeuwen Thomas Tirry Luc |
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Institution: | Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium. Thomas.vanleeuwen@ugent.be |
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Abstract: | A field-collected multiresistant strain of Tetranychus urticae Koch exhibiting high resistance to bifenthrin was investigated in comparison with a susceptible laboratory strain. The esterase inhibitor S,S,S-tributyl-phosphorotrithioate (DEF) was able strongly to synergise bifenthrin toxicity in the resistant strain. Optimal conditions for determining esterase activities in T. urticae were determined, and a higher esterase activity towards several artificial substrates was found in this resistant strain, which had a preference for hydrolysing 4-nitrophenyl butyrate. Bifenthrin was able to bind the active centres of T. urticae esterases in vitro, as was determined after competition experiments by a Dixon plot, revealing a higher affinity of bifenthrin in the resistant strain. Bifenthrin-hydrolysing activity in the resistant and susceptible strains was examined in vitro and quantified with gas chromatography. A 7.2-fold higher metabolising rate was found in the resistant strain. |
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Keywords: | pyrethroid resistance bifenthrin esterases Tetranychus urticae metabolism |
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