| Evergestis extimalis Scopoli has now become a special pest on rape fields in qinghai province.The prevention and control of the Evergestis extimalis Scopoli is mainly dependent on the chemical pesticides,but perennial large number of spraying chemical pesticides has caused it to resistant for them,thus affecting the control.We did some research on monitoring resistance of it to 12 pesticides,And preliminary explored the physiological?biochemical mechanism and resistance of Evergestis extimalis ScopoliThe stomach poisoning method was used to define the toxicity of 12 pesticides for Larvae of Evergestis extimalis Scopoli.The results showed that the LC50 of avermectins,spinosad,chlorpyrifos and beta-cypermethrin to Evergestis extimalis Scopoli treated 24 h with these pesticides were 4.1278-17.0079mg/L had the stronger virulence.The LC50 of three triazophos,carbamic acid,monosultap and pedigree treated with these pesticides were 10.2747-1612.4867mg/L had the low virulence.The LC50 of avermectins,spinosad,beta-cypermethrin,chlorpyrifos and chlorantraniliprole treated with these pesticides were 0.4814-5.5995mg/L had the stronger virulence.The LC50 of three triazophos,carbamic acid,monosultap,pedigree and acephate treated with these pesticides were 8.3911-117.1618mg/L had the low virulence.In 2014-2016 the stomach poisoning method was used to monitoring the resistance of Evergestis extimalis Scopoli for 12 pesticides.The results showed that the chlorantraniliprole had a higher resistance level of Evergestis extimalis Scopoli with the relative resistance ratio is close to or more than14.The chlorfenapyr had a lower resistance level of Evergestis extimalis Scopoli with the relative resistance ratio is close to or less than 1.The resistance level of avermectins,acephate,three triazophos and indoxacarb to all growth trend,including the relative resistance ratio increasese of avermectins and three triazophos from 1.68 and 0.51 to 4.45 and 5.33 respectively.The resistance level of chlorpyrifos,beta-cypermethrin,spinosad,carbamic acid,monosultap,chlorfenapyr,chlorantraniliprole and pedigree to all downtrend,including the chlorantraniliprole relative resistance ratio decreased from 14.10 to 0.45.This article selects the commonly used three kinds of pesticides and the sublethal dose of Evergestis extimalis Scopoli larvae key target enzymes and metabolic enzyme activity change.Results indicated the chlorfenapyr sublethal doses treat Evergestis extimalis Scopoli,the carboxylesterase activity decreased obviously,and GSH-s-transferase activity significantly increased,the activity of acetylcholinesterase has no obvious change.The beta-cypermethrin sublethal doses treat it,the acetyl cholinesterase activity decline but not obvious,carboxylesterase activity down first and then increased,GSH-s-transferase activity changed little.The avermectins sublethal doses treat it,acetyl cholinesterase actiity decreases obviously,GSH-s-transferase activity increased gradually after first being suppressed,carboxylesterase activity increased significantly with the extension of time.Therefore,the three kinds of pesticide sublethal doses were Evergestis extimalis Scopoli target enzyme activity produced obvious inhibition,while on metabolic enzyme activity has obvious entrainment.The co-toxicity of chlorfenapyr,beta-cypermethrin and avermectins was tested by the stomach poisoning method of Evergestis extimalis Scopoli.The results showed that after 24 h avermectins mixed with beta cypermethrin or chlorpyrifos had remarkable synergistic effect,with the co-toxicity coefficient were 302.34 and 441.73 respectively.The beta cypermethrin mixed with chlorpyrifos had antagonistic effect,with the co-toxicity coefficient was 1.19.And afer 48 h avermectins mixed with beta cypermethrin or chlorpyrifos,beta cypermethrin mixed with chlorpyrifos had synergistic effect,with the co-toxiticy coefficient were 644.08?155.21 and 239.58.This shows that avermectins mixed with beta cypermethrin was very effective. |
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