The Risk Assessment Of Neonicotinoids To Natural Enemy Trichogramma Ostriniae (Hymenoptera:Trichogramma Tidae)

The neonicotinoid insecticide is currently the most widely used and the fastest growing class of plant source insecticide in the world.Trichogramma spp.an egg parasitic wasp,is the most studied at domestic and abroad biological control and the most widely used a class of natural enemies insects.Therefore,this study comprehensively evaluated the toxicity of neonicotinoid insecticide to Trichogramma ostriniae.In this study,the acute toxicity of seven new nicotine insecticides to Trichogramma ostriniae was determined by the controlled film method under laboratory conditions;The effect of the recommended concentration of the field on the emergence rate of Trichogramma ostriniae was studied by eggplant dipping method;The effects of sub-lethal doses(LC10,LC25)on the parasitism,the emergence rate and the survival time of Trichogramma ostriniae were determined by the controlled film method.The effects of sub-lethal doses(LC10,LC25)on the activities of three detoxification enzymes in Trichogramma ostriniae were studied by means of controlled film method.1)The results of acute toxicity test showed that the toxicity of neonicotinoid insecticide was high.The order of its toxicity was imidacloprid > thiamethoxam > clothianidin > dinotefuran > acetamiprid > nitenpyram > thiacloprid.The safety evaluation showed that only thiacloprid was a medium risk agent and the others were extremely high risk agents.2)The result of the effect on of the agents' sublethal dose(LC10,LC25)on the parasitic ability,F1 generation eclosion rate and their survival time of Trichogramma ostriniae showed that the two concentrations of each agent did not affect the parasitic rate of Trichogramma ostriniae,but had a certain effect on the F1 generation eclosion rate and their survival time.In addition,the high concentration of the agent had a relatively high toxicity to Trichogramma ostriniae.The toxicity of thiamethoxam,clothianidin and thiacloprid in seven test agents is lower.3)The result of the effect of field concentration on the emergence rate of Trichogramma ostriniae showed that the eclosion rate of Trichogramma ostriniae treated with the seven new nicotine insecticides was decreased in different degrees,and the earlier the treatment period,the lower the eclosion rate.The imidacloprid had the greatest effect on the eclosion of the corn borer,and thiamethoxam and clothianidin had the least affected.4)Thiamethoxam,clothianidin and nitenpyram treatment will increase the activity of three detoxification enzymes at varying degrees.Other agents do not significantly affect the activity of the three detoxifying enzymes at low concentrations,but high concentrations inhibit their activities.The inhibitory effect of acetamiprid on the three detoxification enzymes was the strongest.Seven kinds of neonicotinoid insecticide have high acute toxicity to Trichogramma ostriniae and have medium~ high risk.Neonicotinoid insecticide are low toxicity to the first two stages of Trichogramma ostriniae.And thiamethoxam,clothianidin and nitenpyram can activate the detoxification enzyme activity in insects,thereby reducing the toxicity of pesticides.Therefore,the use o f such drugs in the field with Trichogramma ostriniae for agricultural pest control,we should pay attention to avoid the eclosion period.In addition,according to the length of the duration of different drugs,appropriate time should be chosen to lay the Trichogramma ostriniae.