Risk Analysis Of Pesticide Residues And Application Of Control Factor Ladybug In Nanguo Pear Orchard In Haicheng Area

Chemical control and biological control are two important control methods in plant protection measures.Chemical pesticide has always been the most commonly used control method in agricultural production.Its impact on human beings and ecology is enormous.The use of natural enemies to control pests in biological control has always been the focus of research.Ladybug,as an important natural enemy of pests,has a wide range of species,huge quantity and diversity of predation,and has broad application prospects.Research on pesticide residues in orchards,risk analysis of pesticide use in orchards,combined with ladybug prevention and control,have guiding significance for the implementation of pesticide application reduction technology and reduction of pesticide residues in the future.In this experiment,through the residue detection of several common insecticide in Nanguo pear orchard in Haicheng area,the degradation law of several pesticides in Nanguo pear orchard was analyzed,and the risk of pesticide residue in Nanguo pear orchard was analyzed in combination with the predation ability of ladybug.The following conclusions are drawn:1.Degradation laws of several insecticides.Imidacloprid,acetamiprid,spirotetramat,emamectin benzoate and abamectin all degraded fastest on fallen leaves,the second is branches,the slowest on fruits.Chlorbenzuron degraded fastest on fallen leaves,followed by fruits and slowest on branches.Beta-cypermethrin degrades fastest on branches,next to fallen leaves,and slowest on fruits.The degradation rates of seven pesticides in fruits were chlorbenzuron > emamectin >spirotetramat > imidacloprid > acetamiprid > abamectin > beta-cypermethrin.In the branches,emamectin degrades fastest and acetamiprid degrades slowest.The degradation of emamectin was the fastest and that of beta-cypermethrin was the slowest in deciduous leaves.In actual production,combined with the control object,pesticides that degrade slowly in fruits can be used earlier and pesticides that degrade quickly can be used later,which is of guiding significance for obtaining low residue results.2.Predation ability of ladybug.Harmonia axyridis(Pallas)is the dominant species in Haicheng area.The survival rate of Harmonia axyridis(Pallas)after artificial storage at 0? for 4.5 months is higher than that of naturally overwintering Harmonia axyridis(Pallas).Cold storage at 0 ? and starvation will not affect the predation ability of Harmonia axyridis.The predation ability of artificially preserved Harmonia axyridis returned to normal level after 72 hours of starvation.After 48 hours of starvation,the predation ability of thenaturally overwintering Harmonia axyridis returned to normal level.After 72 hours of starvation,the artificially preserved ladybug recovered its predation ability,which indicated that 72 hours of starvation had already achieved the goal of promoting the feeding of ladybug.According to the test results,the artificially preserved ladybug can be starved for 72 hours after the dormancy is released,so that the food intake in the field can reach more than 90 heads,and the method can play a role in controlling the number of overwintering hibernating stinging pests,reducing the population density of pests,reducing the pressure of medication in the growing season,thereby reducing the dosage or the number of medication and reducing the risk of pesticide residues.3.Risk analysis of several pesticides.Imidacloprid,acetamiprid,chlorbenzuron,beta-cypermethrin and spirotetramat will not cause risks to the residues in fruits,which indicates that this medication is safe.However,there are certain risks in the use of abamectin and emamectin benzoate,and it is suggested to adjust the dosage to 3000?5000 times of liquid.