Search

Tuta absoluta is one of the most devastating and invasive insect pests throughout the world. It feeds on numerous solanaceous plant species and has evolved resistance to various types of popular chemical agents. Tetraniliprole is a novel diamide chemical agent that acts as a modulator of the ryanodine receptor, and it has been considered as a promising insecticide against T. absoluta. In this study, we subjected a T. absoluta strain to 17 generations of continuous selection with tetraniliprole in the lab. The resulting tetraniliprole-selected T. absoluta strain (YN-Tet) exhibited a 12.9-fold higher resistance to tetraniliprole compared with a susceptible strain (YN–S), and the realized heritability (h 2) was estimated to be 0.1437. The YN-Tet strain exhibited a low level of cross-resistance to chlorantraniliprole and significantly higher cytochrome P450 monooxygenase activity. There was a fitness cost of tetraniliprole resistance in the YN-Tet strain, which had a relative fitness of 0.83 compared with the YN-S strain and a significantly lower fecundity per female. These results enhance our knowledge of the risk and mechanism of tetraniliprole resistance, enabling future optimization of resistance management strategies. [Display omitted] • Tuta absoluta has a resistance risk to tetraniliprole after continuous selection. • Tetraniliprole showed low cross-resistance to chlorantraniliprole in T. absoluta. • Piperonyl butoxide exerted synergism in tetraniliprole resistant YN-Tet strain. • Enhanced P450 monooxygenases is involved in the resistance in YN-Tet strain. • Tetraniliprole-resistance conferred significant fitness costs in the YN-Tet strain. [ABSTRACT FROM AUTHOR]

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-Rand 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. [ABSTRACT FROM AUTHOR]