Evaluation of sublethal effects of thiamethoxam on the biological parameters of two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae)

Background and Objectives The two-spotted spider mite Tetranychus urticae Koch(Acari: Tetranychidae) is one of the key pests that can damage a wide range of crops. Materials and Methods In this study, sublethal effects of thiamethoxam (Actara®) in three concentrations including LC5, LC10 and LC20 on biological parameters of two-spotted spider mite was assessed at 25±2 ºC, 60±5 % RH, and a photoperiod of 16:8 (L:D) hr. The life table, reproductive and population growth parameters of T. urticae were also studied. The raw data were analyzed based on two-sex life table analysis. Results Based on the results, sublethal concentrations of thiamethoxam significantly reduced the mean fecundity and lifespan from 61.1 eggs/individual and 23.71 days, respectively in control treatment to 45.89 eggs/individual and 20.89 day in LC20 treatment. The intrinsic and finite rate of increase (r, λ) was not affected by the increase of concentration. The net reproductive rate (R0) reached its lowest level (36.71 offspring/individual) in LC20 treatment. Discussion The results of this study showed that the sublethal concentrations of thiamethoxam affected some biological parameters of T. urticae. The results of this research can be used to design management plans for two-spotted spider mite.