Abstract: 【Aim】 The objective of this research is to determine the effects of total alkaloids from Tripterygium wilfordii Hook. f. on insect nervous system and to provide a basis for elucidating its insecticidal mechanisms. 【Methods】 The 5th instar larvae of Mythimna separata (Walker) were fed with maize leaves treated with the total alkaloids from T. wilfordii. The activities of acetylcholine esterase (AChE), Na⁺, K⁺-ATPase, Ca²⁺, Mg²⁺ - ATPase, glutamic-pyruvic transaminase (GPT) and glutamic decarboxylase (GAD) in the 5th instar larvae of M. separata treated were determined at three different poisoning stages, and the contents of neurotransmitters including acetylcholine (ACh), γ-aminobutyric acid (GABA) and glutamic acid (Glu) were also assayed. 【Results】 The AChE activity in the 5th instar larvae of M. separata was not affected by the total alkaloids from T. wilfordii. The ACh contents in treated larvae in the weak paralysis stage and the deep paralysis stage were not significantly different from those of the corresponding two controls. The GABA contents in treated larvae increased by 89.86%, 49.28% and 20.29%, while the Glu contents increased by 24.55%, 23.33% and 8.13% in the weak paralysis stage, the deep paralysis stage and the recovery stage, respectively. The GPT activity in treated larvae was remarkably inhibited by the total alkaloids, but the GAD activity was not affected. The activities of Na⁺, K⁺-ATPase and Ca²⁺, Mg²⁺-ATPase in the brain of treated larvae were inhibited, but those in the midgut did not change. 【Conclusion】 The results help us understand the effects of the alkaloids from T. wilfordii on insect nervous system, and provide further scientific basis for revealing their action target.

Key words: Mythimna separata, Tripterygium wilfordii , total alkaloids, neural enzymes, neurotransmitter