Synergistic Control Of Apple Mites By Predation And Chemical Pesticides

Spider mite is a kind of harmful mite in orchard,which is mainly controlled by chemical control.Predatory mites are playing an increasingly important role in the control of harmful mites.Studying the synergistic effect of predatory mite and pesticide is of great significance in reducing the dosage and concentration of pesticide.The study investigated the population occurrence of predatory mites and spider mites in apple orchards.The virulence effects of 14 acaricides on Tetranychus urticae at the recommended doses in the field were observed.There were 12 varieties of acaricides to test the virulence of different predatory mites,spider mites in different regions,and screen out acaricides that are more harmful to spider mites and relatively safe to predatory mites.In addition,the control effect of several safe acaricides synergistically with predatory mites on Tetranychus urticae was observed.In order to verity the synergistic effect of predatory mites and acaricides.The main research contents and results are as follows:1.In 2019 and 2020,a dynamic survey of mites was carried out in the apple orchard of the Xinxiang Experimental Base.The result showed:the species of predatory mite that occured in the orchard was Amblyseius pseudolongispinosus and Amblyseius orientalis.The species of spider mite in the orchard was Amphitetranychus viennensis.On apple trees that have not been treated with acaricides,there are more predatory mites,and the Amphitetranychus viennensis can be better controlled.However,the number of predatory mites on the apple trees after treatment with pyridaben decreased significantly.2.According to the recommended field doses of 14 common acaricides commonly used in orchards,the virulence of Tetranychus urticae in different areas was determined.The result showed:Most of the 14 acaricides failed to show good acaricidal effects on the populations of Tetranychus urticae in 3 regions,but they all reduced the number of offspring of Tetranychus urticae.3.The toxicity of common acaricides to spider mites and predatory mites in different areas was determined.The result showed:three populations of Tetranychus urticae（Shangqiu population,Lingbao population and Aksu population）showed high levels of resistance to 12 acaricides.What’s more,Tetranychus urticae in Shangqiu and Aksu regions showed high resistance levels,and the LC₅₀of most acaricides reached more than 300mg.L^-1;Two geographic populations of Tetranychus viennensis（Xinxiang population and Lingbao population）showed low level of resistance to 12 pesticides,and the LC₅₀of most acaricides was within 100mg.L^-1.And there was no significant difference in resistance between the two populations;Neoseiulus barkeri had strong resistance to most acaricides,the LC₅₀of most acaricides was above 1000mg.L^-1.The second most resistant was Amblyseius orientalis.However,Neoseiulus cucumeris was less resistant to acaricides,and the LC₅₀of most acaricides is within300mg.L^-1.4.Using the toxicity selectiove ratios to evaluate the safety of predatory mites.The result showed:Acaricides were safer to the Neoseiulus barkeri.For the Tetranychus urticae,most pesticides were low security for Amblyseius cucumis and Amblyseius orientalis.However,for the Tetranychus hawthorne,most pesticides were highly safe to Amblyseius cucumis and Amblyseius orientalis.5.Using the synergistic effect of predatory mites and safe acaricides to control Tetranychus urticae,and observe the synergistic control effect.The result showed:compared with the effect of predator mites alone,the synergistic effect of Neoseiulus barkeri and safe acaricides（bifenazate and propargite）on Tetranychus urticae was better,and both have reached more than 90%.As for Neoseiulus barkeri and the highly toxic acaricide（pyridaben）,the control effect of combination on Tetranychus urticae was worse than predator mites alone,the effect of it was 11.63%.