Study On The Control Potential Of Two Predatory Mites On The Harmful Mites In Apple Orchard

Apple is one of the most important fruits with the largest planting area and the most important economic status in China,but it is often seriously harmed by Tetranychus viennensis,Tetranychus urticae and Panonychus ulmi.Long-term chemical control will not only improve the resistance of harmful mites,kill natural enemies,affect the quality and safety of fruit,but also cause pressure on the ecological environment.Biological control with predatory mites as an important component has been paid more and more attention.In order to clarify the control potential of two commercial predator mites Neoseiulus californicus and Neoseiulus barkeri on harmful mites in northern orchards,the predatory predation of two predator mites on three harmful mites in apple orchards under indoor conditions and the control effect of N.californicus released from orchards on T.viennensis were studied,and the drug sensitivity of two predator mites to common medicines in orchards was determined.The results are as follows:1.Predatory effects of N.californicus and N.barkeri on A.viennensisPredatory responses of N.californicus and N.barkeri to A.viennensis were measured at25℃.The results showed that the functional responses of N.californicus and N.barkeri to various mite states of A.viennensis belonged to HollingII type.The predation ability（a/T_h）of N.californicus to A.viennensis larvae was the largest,The predatory capability parameters（a/T_h）was 85.5992,followed by eggs,The predatory capability parameters（a/T_h）was49.4994 and that of N.barkeri to A.viennensis egg（a/T_h）was the largest,The predatory capability parameters（a/Th）was 74.1886,followed by larvae,The predatory capability parameters（a/Th）was 65.6637.The predation ability of N.barkeri to the eggs of A.viennensis is higher than that of N.californicus,but the predation ability of other mite states is lower than that of N.californicus.N.californicus had a predatory effect on A.viennensis eggs,larvae and protonymph（Q>1）,N.barkeri had a predatory effect on A.viennensis eggs,larvae（Q>1）,Both predatory mites had strong intraspecific interference effects when they preyed on A.viennensis,and N.californicus had greater intraspecific interference effects.The interference models were E=0.0717P^-0.4134 and E=0.0466P^-0.1967.2.Predatory effects of N.californicus and N.barkeri on T.urticaePredatory responses of N.californicus and N.barkeri to T.urticae were measured at 25℃.The results showed that the functional responses of N.californicus and N.barkeri to various mite states of T.urticae belonged to HollingII type.The predatory capacity（a/T_h）of N.californicus to T.urticae eggs was the largest,The predatory capability parameters（a/Th）was57.7575,followed by larvae,The predatory capability parameters（a/Th）was 39.5887,and that of N.barkeri to T.urticae eggs（a/T_h）was the largest,The predatory capability parameters（a/T_h）was 89.6953,followed by larvae,The predatory capability parameters（a/T_h）was55.4759.The predation ability of N.barkeri to eggs,larva and adult of T.urticae is higher than N.californicus,but the predation ability of other mite states of T.urticae is lower than that of N.californicus.N.californicus and N.barkeri had a predatory effect on T.urticae eggs and larvae（Q>1）;Both predatory mites had strong intraspecific interference effects when they preyed on T.urticae,and N.californicus had greater intraspecific interference effects.The interference models were E=0.0720P^-0.3285 and E=0.0654P^-0.3235.3.Predatory effects of N.californicus and N.barkeri on P.ulmiPredatory responses of N.californicus and N.barkeri to P.ulmi were measured at 25℃.The results showed that the functional responses of N.californicus to each mite state of P.ulmi belonged to HollingII type.The functional responses of N.barkeri to P.ulmi eggs,larvae,protonymph and deutonymph belonged to HollingII type,and N.barkeri had small predation of P.ulmi adult,which could not fit the functional reaction equation.Predatory ability（a/T_h）of N.californicus to P.ulmi eggs was the largest,The predatory capability parameters（a/Th）was 39.6629,followed by larvae,The predatory capability parameters（a/Th）was 37.0619,and N.barkeri to P.ulmi larvae（a/T_h）was the largest,The predatory capability parameters（a/T_h）was 27.3125,followed by egg,The predatory capability parameters was（a/T_h）17.0224.The ability of N.californicus to control the mites of P.ulmi was higher than that of N.barkeri.N.californicus and N.barkeri had a predatory effect on eggs,larvae and protonymph of P.ulmi（Q>1）.Two predatory mites had strong intraspecific interference effects on P.ulmi.and N.californicus had greater intraspecific interference effects.The interference models were E=0.0496P^-0.54360.5436 and E=0.05136P^-0.4355.4.Sensitivity of N.californicus and N.barkeri to 8 Orchard DrugsSensitivity of N.californicus and N.barkeri was determined by residual toxicity method of indoor leaves.The results showed that bifenazate,spirodiclofen,pymetrozine,thiamethoxam and chlorantraniliprole had no significant toxicity to N.californicus and N.barkeri in 24 hours,but pyridaben,tebufenozide and avermectin had significant toxicity to N.californicus and N.barkeri in 24 hours,and the LC₅₀ of N.barkeri to the three agents was higher than N.californicus.The toxicity of three toxic agents to N.californicus was as follows:abamectin>tebufenozide>pyridaben,LC₅₀ was 14.686 mg/L,18.348 mg/L and33.765 mg/L respectively,and to N.barkeri was as follows:abamectin>pyridaben>tebufenozide,LC₅₀0 was 81.407 mg/L,176.011 mg/L and 232.26 mg/L respectively,and the LC50 of N.barkeri was higher than that of N.californicus.According to the test standards for chemical pesticide environmental safety assessment test standards,Avermectin and pyridaben showed moderate risk to N.californicus,tebufenozide showed high risk to N.californicus,avermectin showed low risk to N.barkeri,pyridaben and tebufenozide showed moderate risk to N.barkeri.5.Control of A.viennensis by releasing N.californicus from apple orchardsA month after the release of N.californicus from apple orchards in the north,the number of A.viennensis in the control area began to rise,while the number of A.viennensis in the release area continued to be 0,indicating that N.californicus could effectively control A.viennensis,and the release of N.californicus had a certain impact on the number of local predatory mites.