Keywords: 
• insecticide /
• Paratenodera sinensis Saussure /
• toxicity /
• LC₅₀

Abstract: Mantis is one of the important predators in fields to control pest populations. In this study, the 3-instar mantis (Paratenodera sinensis Saussure) was exposed to different concentrations of nine kinds of commonly used insecticides. LC 50 and mortality were measured to evaluate the toxicity of various insecticides to mantis. The results showed that there was significant difference in toxicity (LC₅₀) to mantis between these insecticides. After mantis exposed to the insecticides for 24 h, the range of LC₅₀ values was in 0.7182~347.7962 mg·L^-1, and that of LC95 values was in 8.8057~1 734.5650 mg·L^-1. After mantis 48 h exposure to the insecticides, LC₅₀ and LC95values were in the range of 0.3564~193.6887 mg·L^-1 and 3.8958~1 548.3258 mg·L^-1, respectively. LC₅₀ values were 0.2232~115.3391 mg·L^-1, and the LC95 values were 1.7730~530.6462 mg·L^-1 after a 72 h exposure to the insecticides. The most significant difference among the toxicity of the insecticides to mantis was up to 543.46 times. The order of toxicity to mantis was lambda-cyhalothrin > acetamiprid > bifenthrin > chlorpyrifos > thiamethoxam > indoxacarb > imidacloprid > abamectin > Bacillus thuringiensis (Bt). According to the mortality of mantis tested in recommended in field doses of insecticides, to mantis, chlorpyrifos, bifenthrin, acetamiprid and lambda-cyhalothrin were toxic, Bt was in a moderate level. Imidacloprid, indoxacarb and thiamethoxam were in very low toxicity, and abamectin was nearly harmless. According to the ratio of LC₅₀ to field recommended concentration, the use of abamectin and imidacloprid did not affect the mantis population. While Bt, indoxacarb and thiamethoxam could influence mantis population, and chlorpyrifos, acetamiprid, bifenthrin and lambda-cyhalothrin seriously affected the stability of the population. In the exposure time range of 24 to 72 h, LC₅₀ and LC95 of pesticides decreased with increase of exposure time, indicating that toxic effect of pesticides was proportional to exposure time. Therefore, lambda-cyhalothrin, bifenthrin, acetamiprid and chlorpyrifos were suggested to reduce the application to mantis's living areas. To the recommended field usage, not only the effects of pest control but also the hazards to natural enemies should be considered to increase the use safety of pesticide and protect the stability of natural enemy population.