title: [Resistance mechanisms of Spodoptera exigua (Hübner) to fenvalerate and alpha-cypermethrin].
abstract: By using synergist bioassay and biochemical analysis, this paper approached the resistance mechanisms of Spodoptera exigua (Hübner) to fenvalerate and alpha-cypermethrin. The synergistic ratios of piperonyl butoxide (PBO), o, o-diethyl-o-phenyl-thiophosphate (SV1), triphenyl phosphate (TPP), and diethyl maleate (DEM) between fenvalerate-resistant strain (Fen-R) and susceptible strain were 10.2, 7.8, 12.5, and 1.1, and those between alpha-cypermethrin resistant strain (Cyp-R) and susceptible strain were 21.6, 15.5, 8.6, and 1.2, respectively. Significant synergisms of PBO, SV1, and TPP to fenvalerate and alpha-cypermethrin were observed, implying that multifunctional oxidase and carboxylesterase were involved in the resistance to fenvalerate and alpha-cypermethrin. The carboxylesterase activities in the fourth instar larvae of Cyp-R and Fen-R strains were 1.9 and 2.2 folds of the corresponding susceptible strains, respectively, but no differences were found in the glutathione-S-transferase activities between the resistant and susceptible strains, which indicated that carboxylesterase played an important role in the resistance of S. exigua to fenvalerate and alpha-cypermethrin, while glutathione-S-transferase contributed little to the resistance. There were no significant differences in the Na-K-ATPase activities between the resistant and susceptible strains, but the inhibition of fenvalerate and alpha-cypermethrin on Na-K-ATPase was higher in the susceptible strains than in the resistant strains, indicating the decreased sensitivity of Na-K-ATPase in resistant strains.
authors.affiliation: College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China. yiquanlan@163.com
authors.forename: Yi-Quan
authors.initials: YQ
authors.lastname: Lan
authors.forename: Shi-Xi
authors.initials: SX
authors.lastname: Zhao
mesh_terms: D000818:Animals; D007305:Insecticide Resistance / Q000187:drug effects* / Q000502:physiology; D007306:Insecticides / Q000494:pharmacology; D007915:Lepidoptera / Q000187:drug effects* / Q000502:physiology; D009570:Nitriles / Q000494:pharmacology*; D010755:Organophosphates / Q000494:pharmacology; D010882:Piperonyl Butoxide / Q000494:pharmacology*; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D009570:Nitriles; D010755:Organophosphates; D011722:Pyrethrins; C017160:cypermethrin; D010882:Piperonyl Butoxide; C005445:triphenyl phosphate; C017690:fenvalerate