Effects Of Three Major Metabolic Enzyme Inhibitors On The Insecticidal Activity Of Haedoxan A And And The Synergistic Effect Of Phrymarolin ?

Haedoxan A and phrymarolin I are lignan compounds isolated from Phryma leptostachya.Among them,haedoxan A has insecticidal activity and is equivalent to the insecticidal activity of synthetic pyrethroid insecticides.Although the insecticidal activity of phrymarolin I is not significant,it has synergistic effect on carbamate and pyrethroid insecticides.However,the mechanism of insecticidal action of haedoxan A and the synergistic mechanism of phrymarolin I have not been clear so far,which greatly limits its further research and application.To determine the insecticidal activity of haedoxan A and phrymarolin I and its effects on the activities of three major metabolic enzymes.In this study,Mythimna separata was used as the tested insect.The three main metabolic enzyme inhibitors in the insect,0piperonyl butoxide?PBO?,triphenyl phosphate?TPP?and diethyl methoxyborane?DEM?were used as synergists.The aim is to reveal the insecticidal mechanism of haedoxan A and the synergistic mechanism of phrymarolin I.The main results are as follows:1.Haedoxan A has gastric toxicity activity to 3rd instar M.separata,and the LC₅₀value was 27.06?g/mL after 24h.Phrymarolin I showed only narcosis activity to third instar M.separata and NC₅₀ value was 3157?g/mL after 4h.Permethrin had stomach toxicity and contact toxicity against third instar M.separata,and LC₅₀ value was 2.8?g/mL and 0.31?g/mL after 24h respectively.2.PBO,TPP and DEM can improve the stomach toxicity of haedoxan A and phrymarolin I on 3rd M.separata.The synergistic effect of feeding enzyme inhibitors on haedoxan A was PBO>TPP>DEM,and the corresponding synergistic ratios were 2.72,1.91and 1.71.The synergistic effect of mixture of PBO and DEM was the most obvious.The synergistic ratios was 9.63;The synergistic effect of the drip enzyme inhibitor on haedoxan A was PBO>DEM>TPP,and the corresponding synergistic multiples were 4.04,3.59 and2.9;All three enzyme inhibitors can make the phrymarolin I to the 3rd instar M.separata showed gastric toxicity activity,synergistic effect was TPP>PBO?DEM,the synergistic multiple was 8.81,1.31,1.23.3.Haedoxan A can significantly increase the activity of carboxylesterase in the 3rd instar M.separata.The activation level increases first and then decreases with the increase of concentration.It reaches the peak in LC₇₅,and the activation rate is 100%to 189.12%.The degree of activation of NADPH-cytochrome C reductase decreased with the increasing concentration,and the activation rate is 181.21%to 331.2%.The inhibition of glutathione-S-transferase was significant,the inhibition rate increased first and then decreased with the change of concentration,and it reaches the peak in LC₅₀,the inhibition rate is 31.1%⁴2.86%.4.phrymarolin?has a significantly synergistic effect on haedoxan A and permethrin.After feeding the phrymarolin?,the virulence of haedoxan A to the 3rd instar M.separata was increased by 2.28 times,and the synergistic ability of phrymarolin?is between PBO and DEM.The stomach activity of permethrin is increased by 56 times;Under the action of phrymarolin I,the LC₅₀ of permethrin on the contact activity of 3rd instar M.Separata was0.021?g/mL,the activity was increased by 14.76 times,and the synergistic effect was similar to TPP.5.Phrymarolin?can significantly improve the carboxylesterase activity of 3rd instar M.separata,the activation degree is positively correlated with the concentration,the activation rate is 10.88%to 117.39%.The activation degree of glutathione-S-transferase increased first and then decreased with the change of concentration,it reaches the peak in LC₅₀,and the activation rate is 38.99%to 103.35%.The effect of NADPH-cytochrome C reductase activity was firstly inhibited and then activated.LC₁₀-LC₇₅ concentration was inhibited,the inhibition rate is between 6.25%and 37.5%,and the LC₉₀ activation rate is6.24%.The above results indicate that the microsomal multifunctional oxidase and carboxylesterase are the main metabolic enzymes of haedoxan A,and the carboxylesterase is the main metabolic enzyme of phrymarolin?.Phrymarolin?can be developed as a synergist.