The influence of temperature on the toxicity of insecticides to Nilaparvata lugens (Stål)

Abstract

The toxicity of insecticides is associated with a variety of factors including temperature, and global warming is bound to lead to the outbreak of pests; therefore, it is important to study the influence of temperature on insecticide toxicity and pest control. In this study, the influence of temperature on the toxicity of insecticides to Nilaparvata lugens (BPH) was determined. The results showed that the sensitivity of BPH to cycloxaprid (LC₅₀ = 42.5-0.388 mg/L), nitenpyram (LC₅₀ = 3.49-0.187 mg/L), triflumezopyrim (LC₅₀ = 0.354-0.0533 mg/L) and chlorpyrifos (LC₅₀ = 36.3-7.41 mg/L) increased significantly when the temperature changed from 18 °C to 36 °C. BPH sensitivity to etofenprox (LC₅₀ = 9.04-54.2 mg/L) was also affected by temperature. Additionally, the feeding amount and the activities of three detoxification enzymes [cytochrome P450 (P450), glutathione S-transferase (GST) and carboxylesterase (CarE)] of BPH at different temperatures were also measured. The feeding amounts were positively correlated with temperature increases while the activities of P450 and GST were significantly inhibited. The correlation analysis showed that changes in P450 activity (but not GST activity) were closely related to the sensitivity of BPH to cycloxaprid, nitenpyram, chlorpyrifos, and etofenprox according to the variation in temperatures. This study provides a theoretical basis for the rational use of chemical pesticides under the global warming trend and provides a reference for the integrated management of BPH in the field.

Keywords: Detoxification enzyme; Feeding capacity; Insecticides; Nilaparvata lugens; Temperature; Toxicity.