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Relative contribution of detoxifying enzymes to pyrethroid resistance in a resistant strain of Helicoverpa armigera
Author(s) -
Yang E.,
Yang Y.,
Wu S.,
Wu Y.
Publication year - 2005
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/j.1439-0418.2005.00999.x
Subject(s) - deltamethrin , piperonyl butoxide , pyrethroid , fenvalerate , bifenthrin , biology , cypermethrin , cyhalothrin , helicoverpa armigera , toxicology , strain (injury) , phoxim , esterase , biochemistry , enzyme , pesticide , botany , larva , agronomy , anatomy
The relative contribution of oxidases and esterases to pyrethroid resistance was studied in a YS‐FP strain of Helicoverpa armigera from China. The YS‐FP strain was derived from a field‐collected strain (YS) by 16 generations of selection with a mixture of fenvalerate and phoxim. Compared with the YS strain, the YS‐FP strain showed 1850‐ to >7140‐fold resistance to four ester‐bonded phenoxybenzyl alcohol pyrethroids (fenvalerate, deltamethrin, cypermethrin and cyhalothrin), >205‐fold resistance to a non‐ester phenoxybenzyl alcohol pyrethroid (etofenprox) and only 19‐fold resistance to an ester‐bonded methylated biphenyl alcohol pyrethroid (bifenthrin). The oxidase inhibitor piperonyl butoxide eliminated most the of resistance to fenvalerate, deltamethrin, cypermethrin, cyhalothrin and etofenprox, whereas the esterase inhibitor S,S,S ‐tributylphosphorothioate had a small synergistic effect for fenvalerate and cyhalothrin only. This suggests that the resistance to these pyrethroids in the YS‐FP strain was mainly because of enhanced oxidative detoxification. The monooxygenase activities of the midguts of sixth‐instar larvae of the YS‐FP strain to substrates p ‐nitroanisole, ethoxycoumarin and methoxycoumarin were 3.7‐, 4.7‐ and 10‐fold, respectively, compared with that of the YS strain. Glutathione S ‐transferase activity and esterase activity were not significantly altered in the YS‐FP strain. This confirms that enhanced oxidative detoxification was a major mechanism contributing to pyrethroid resistance in the YS‐FP strain.