Study On Insecticidal Target Of Terpinen-ol Analogues

Mechanism of insecticides is one of the main contents of pesticide toxicology, and it is also the important theoretical base to develop novel pesticides. Terpine-4-ol is a terpenoid compound existing in many plants. And terpinen-4-ol has strong fumigation, repellent, and contact toxicity on Plutella xylostella, Mythimna separate, Heliothis armigera Hubner, and Sitophilus zeamais Motschulsky. In order to verify the insecticidal action target of terpinen-4-ol, based on acquired insecticidal activity of terpinen-4-ol and its derivatives towards houseflies, the activity of Na+,K+-ATPase of the adults of houseflies tested were determined in vivo and vitro. The main results are given as follows:1. The fumigation activity of terpinen-4-ol and its derivatives against the adults of Musca domestiea L. was tested. The results showed that the fumigation activity of most derivatives were lower than terpinen-4-ol, and only the products of chloro-substituted and epoxied showed much higher fumigation activity , which were 1.72 and 2.67 times of terpinen-4-ol, with LC50 2.61and 1.68μL/L ,respectively.2. The terpinen-4-ol and its derivatives had notable contact activity against housefly. Z2 had the best contact activity, and the LD50 value was 0.0387 mg/insect which is 3.42 times of terpinen-4-ol; Z4,Z5,Z6 also had higher contact activity than terpinen-4-ol, and the LD50 valued 0.0555, 0.0778 and 0.0948mg/insect; the contact activity of Z3 was 1.7324mg/ insect, which was lower than terpinen-4-ol; and contact activity of the other derivatives were equivalent to that of terpinen-4-ol.3. The typical poisoning symptoms of terpiene-4-ol and its derivatives against housefly were excitation, convulsion, paralysis, and death. The differences among the 20 compounds were poisoning speed and the degree of symptom.4. The optimum reaction conditions of Na+,K+-ATPase in head nervous system of Musca domestiea L were determined. The results indicated that the optimum pH value was 7.2, the optimum temperature was 37℃,and the substrate concentration was 0.6mmol/L.5. There was well correlation between the LD50 of terpinen-4-ol derivatives to housefly and the I50 of terpinen-4-ol derivatives to Na+,K+-ATPase in housefly.5. The terpiene-4-ol and its derivatives all had strong inhibition on Na+,K+-ATPase of housefly. In vitro the inhibition rate was gradually increased with poisoning symptom exacerbating. In vivo, the inhibition of Na+,K+-ATPase activities by 20 compounds was concentration dependent.6. It is clear that significantly correlation exists between contact toxicity of those chemicals against housefly and inhibition of Na+,K+-ATPase. The main insecticidal actions of terpiene-4-ol and its derivatives against housefly were fumigation and contact activity, and the contact activity was better than fumigation. The 20 compounds also had obvious inhibition effect on Na+,K+-ATPase. Therefore we speculate that Na+,K+-ATPase is one the important action targets of terpinen-4-ol...