Study On The Response And Mechanism Of Myzus Persicae To Sublethal Concentrations Stress Of Three Neonicotinoids Insecticides

The green peach aphid,Myzus persicae Sulzer?Hemiptera:Aphididae?,is one of the most destructive and cosmopolitan insect pest of economical crops.The green peach aphid feeding can cause direct damage andmay cause indirect damage through the transmission over100 plant pathogenic viruses.Control of M.persicae has been dependent the use of chemical insecticides which frequently resulted in development of resistance to various classes of insecticides,including organophosphates,carbamates,pyrethroids,and neonicotinoids.Therefore,Under such a background,the development and application of new insecticides which environment safety and different modes of action remain critical will provide assurance for effective control.Flupyradifurone,sulfoxaflor and cycloxaprid are three the newest insecticides of the class of new nicotinic insecticides,and they exhibits a high degree of efficacy against a wide range of sap-feeding insects and has great potential in IPM?Integrated Pest Management?of M.persicae.In order to evaluate the effect of insecticides on insect pests,it is not enough to consider the toxic activity,and more importantly,the continuous effect on insect population after the application of insecticides should be fully considered.In this paper,the sublethal effects of three insecticides on M.persicae were studied under laboratory conditions,andthe physiological metabolic mechanism of the sublethal effect was explained,and the differential genes of green peach aphid under the action of three insecticides were excavated.The biological,ecological,physiological,biochemical and gene levels revealed the response and action mechanism of M.persicae to the sublethal dose stress of three insecticides,and comprehensively evaluated the potential effects of three new insecticides on green peach aphid,which provided a theoretical reference for slowing down the development of resistance and rational use of the three insecticides.The main findings are as follows:1.Four instar nymphs treated with three insecticides(LC₁₀and LC₃₀)for a short time?24hours?could significantly reduce the reproduction and longevity of individuals?F₀generation?infected with the aphid,and the adverse effect was significantly enhanced with the increase of the treatment concentration;The sublethal doses(LC₁₀and LC₃₀)of fipronone and epoxididine,and the treatment group(LC₁₀and LC₃₀)of fipronil can shorten the development period and the early stage of oviposition of the offspring?F₁?,showing not only some obvious development stimulating effect,but some inhibition effect on fecundity,Treatment with LC₃₀could slow down the development of F₁generation and significantly reduce the fecundit;In terms of population parameters,sublethal dose stress in the treatment groups of fipronone,epoxididine LC₁₀and LC₃₀and fipronil LC₁₀could promote the population growth of peach aphid progeny,which showed that the intrinsic growth rate was significantly increased and the average generation was significantly shortened;However,the growth of the progeny population of aphid in LC₃₀group was seriously restricted,which showed that the intrinsic growth rate and net reproductive rate were significantly reduced,while the average generation cycle was prolonged.Therefore,it was not difficult to see that the sublethal doses(LC₁₀and LC₃₀)of fipronone and epoxididine could cause the toxic excitation effect of aphid population,and the LC₁₀dose of fipronil could also cause the excitation effect above,but the LC₃₀dose treatment could significantly inhibit the growth of aphid population,2.Sublthal doses(LC₁₀and LC₃₀)of insecticides had withdrawal effect to M.persicae.Insecticides at sublethal levels could stimulate the dispersal behavior of green peach aphid to different extent.The dispersal rates of M.persicae increased along with the passage of time after treatment.but the dispersal behavior caused by different insecticides is different.The dispersal behavior of green peach aphid showed obvious correlation with pesticide concentration in the groups of sulfoxaflor and cycloxaprid,The sublethal effect on the behavior of aphid could be one of causes of inducement pest resurgence.3.Under the sublethal doses(LC₁₀and LC₃₀)of three insecticides,the target enzymes and the activity of detoxification enzyme were affected to some extent,but the stress response were not completely the same;The enzyme activities of ACh E showed inhibitory effect with sublethal concentration on sulfoxaflor,flupyradifurone and cycloxaprid.Forflupyradifurone and sulfoxaflor,with the treatment time was prolonged,enzyme activities reduced.For Car E,the enzyme activity of flupyradifurone and sulfoxaflor was significantly inhibited,while the group of cycloxaprid showed inducement effect.Sublthal concentration of flupyradifurone,sulfoxaflor and cycloxaprid have significant inhibitory effects on GSTs in green peach aphids.The enzyme activities of MFO showed a trend of first increasing and then decreasing,which showed the stimulated effect by treatment of LC₁₀of flupyradifurone,and the enzyme activities of MFO were induced by LC₃₀of flupyradifurone.MFO enzyme activity showed an obvious upward trend by treatment sublethal doses of sulfoxaflor and cycloxaprid,with an obvious induction effect.The results showed that except GSTs,all enzymes may be the detoxifying enzyme in the detoxification metabolism of insecticides by M.persicae and playa major role in the subsequent resistance formation.4.The results showed that the total fatty acid content and total sugar content of M.persicae were significantly decreased,but there were significant differences between fatty composition and content of fatty acids and monosaccharides in each treatment group.The free aminos and the total amino acid in green peach aphid were significantly decreased by the sublethal dose stress of flupyradifurone and sulfoxaflor.It is suggested that the nutrients such as fat,amino acid and carbohydrate may be involved in the degradation and metabolism of insecticides.5.In order to investigate the mechanism of the sublethal effect of peach aphid on three insecticides,the transcriptome analysis of group 7 insect samples was carried out.The results showed that the gene expression of peach aphid showed obvious different trend.After sublethal dose treatment,the differentially expressed genes of insecticides were mainly related to detoxification enzyme system,specifically cytochrome P450,carboxylase and so on.Carbohydrate transport and metabolism,Defense mechanisms,energy production and conversion.A comparison with the sublethal dose group found that the differentially expressed genes were mainly focused on energy,substance metabolism and defense systems,such as carbohydrate transport and metabolism,defense mechanisms,energy production and conversion.In summary,flupyradifurone,sulfoxaflor and cycloxaprid sublethal doses can induce toxic hormesis in M.persicae?F₁?.Therefore,we should be scientific and rational use of pesticides,reduce the frequency of pesticide use,in order to slow down the development of drug resistance and the emergence of pest resurgence.In addition,under the stress of insecticides,M.persicae can detoxify and save some insect individuals by improving the ability of diffusion and nutrition metabolism.And the levels of some P450s genes were over expressed clearly,these indicated that P450s might be involved in the detoxification of M.persicae to insecticides.