Effect Of Temperature On The Toxicity Of Several Insecticides To Sitobion Avenae (Fabricius) And Apolygus Lucorum (Meyer-Dür)and On The Enzyme Activity

Influence of temperature on pesticides activity is complex. Not only the different types of pesticides have different temperature effect, but also, the same kind of pesticides on different insects and even the different varieties of the same pesticides potion to the same insects, the temperature effect also has a bigger difference. In addition to the nature of the drug itself, the test object (worm), the spraying method and the observation of temperature range all influence the temperature effect. We measured the toxicity of several insecticides to Sitobion avenae and Apolygus lucorum under a consistent different temperature. Activity of three detoxifying enzymes and one target enzyme were also examined. The main results are as follows:1. The toxicity of eight conventional insecticides to Apolygus lucorum was measured at 15℃、20℃、25℃、30℃and 35℃respectively by food impregnation method. The results show that: the toxicity of organophosphate and carbamate insecticide is less influenced by temperature, especially phoxim. Temperature almost has no effect on the toxicity of phoxim. Methomyl has a maximum LC50 at 30℃, which is 2.30 times than 15℃. Methomyl is showed to be a negative temperature coefficient insecticide. Carbosulfan has a maximum temperature coefficient for +2.36 at 20℃.β-cypemethrin andλ-cyhalothrin are obvious negative temperature coefficient insecticides on Apolygus lucorum. The toxicity of Beta-cypemethrin is higher and more influenced by temperature thanλ-cyhalothrin. Imidacloprid and acetamiprid are positive temperature coefficient insecticides. The toxicity of imidacloprid is more influenced by temperature than acetamiprid. Imidacloprid has a maximum temperature coefficient for +22.45, and acetamiprid for + 8.87. The temperature coefficient of fipronil at 20℃and 25℃are -5.76 and -2.12, and at 30℃and 35℃are +1.03 and +3.40.2. The toxicity of eight conventional insecticides to Sitobion avenae was measured at 10℃, 15℃, 20℃and 25℃respectively by impregnation method. Through the experiment it can be concluded thatβ-cypermethrin performs negative temperature coefficient to Sitobion avenae, acetamidine are irregular positive temperature coefficient insecticide, the toxicity ofλ-cyhalothrin is influenced by temperature slightly. The other insecticides perform to be positive temperature coefficient insecticides obviously, especially organophosphate insecticides. The temperature coefficient of phoxim between 10℃and 25℃is +27.17, and chlorpyrifos’is +58.70. Methomyl and carbosulfan’s temperature coefficients are +7.77 and +5.04 respectively.β-cypermethrin decreased with temperature rise, but its slightly rose at 25℃. Temperature affects the toxicity ofλ-cyhalothrin slightly, with the maximum temperature coefficient -1.74 in 15℃temperature range. Imidacloprid’s temperature coefficient is +7.64 in 15℃temperature range. The temperature coefficient of acetamiprid at 15℃is -2.54, at 20℃is +1.03, at 25℃is +1.68 respectively.3. Temperature influences the enzyme activity of Sitobion avenae and Apolygus lucorum to some extent. In the temperature range, GST activity of Sitobion avenae improves with the temperature rise. But GST activity of Apolygus lucorum is influenced by temperature complexly, present volatility. The activity of GST is related to negative temperature coefficient. The activity of CarE and AChE are drop with the temperature rise, which is one reason of positive temperature coefficient insecticides. O-demethylase activity of Sitobion avenae is rise at 25℃, but Apolygus lucorum’s is drop at 30℃and 35℃.