Toxicity Effect of Three Insecticides on Important Pests and Predators in Tomato Plants

摘要

The objective of this study was to evaluate insecticide toxicity on Bemisia tabaci, Tetranychus evansi, Orius insidiosus, Cycloneda sanguinea and Chauliognathus flavipes in tomato plants. The following toxicity treatments were applied: T1: control, T2: chlorpyrifos (Pitcher) 450 EC (1.25 L.ha-1), T3: chlorpyrifos 450 EC (Pitcher) (0.62 L.ha-1), T4: thiamethoxam 100 WG (1.00 L.ha-1), T5: thiamethoxam 250 WG (0.50 L.ha-1), T6: teflubenzuron 150 CS (0.025 L.ha-1) and T7: teflubenzuron 150 CS (0.0125 L.ha-1). For the sub-lethal effect, a tenth of the recommended concentration was used. The insecticide teflubenzuron was effective against whitefly nymphs, while chlorpyrifos and thiamethoxam were efficient against adult whiteflies. Insecticides at the dose and lower dose were not efficient to control the adults and nymphs of mite T. evansi. Teflubenzuron was selective at the two doses tested against C. sanguinea and C. flavipes, while thiamethoxam was selective (lower dose) against these two predators. Chlorpyrifos was selective against C. flavipes (lower dose). All insecticides were selective or moderately selective at 21 days after application. Insecticides were not efficient to control the adults and nymphs of T. evansi. The growth regulating insecticide teflubenzuron was effective against whitefly nymphs. Chlorpyrifos and thiamethoxam were efficient against adult whiteflies. In general, the insecticides neonicotinoid and pyrethroid were selective to three predatory species and had lower sublethal impact compared with the organophosphate.