Population Dynamic Of Chromaphis Juglandicola And Control Effect Of Dominant Natural Enemies To Chromaphis Juglandicola

Chromaphis juglandicola is one of the key walnut pest in Xinjiang,and the outbreak of C.juglandicola severely hindered the healthy and sustainable development of the walnut industry.In order to understand the population dynamic of C.juglandicola and its main natural enemies,the population numbers and natural enemies of C.juglandicola were investigated inWensu,Akesu and Gongliu,Yili.The control effect of dominant natural enemies on C.juglandicola were studied,which provide scientific basis for the biological control of C.juglandicola.The main results are as follows:1.The population dynamics of C.juglandicola were different with different locations.The peak time was late-June and early-July in Wensu,Akesu,while the peak time was early-August in Gongliu,Yili.The number of C.juglandicola was the least in the walnut-alfalfa intercropping system.2.The natural enemies of C.juglandicola in different intercropping system were Hippodamia variegate,Chrysopa septempunctata Wesmael,spider,Syrphidae in Wensu,Akesu,and the domaint natural enemy was H.variegate.The walnut-alfalfa intercropping has the most natural enemies.The natural enemies of C.juglandicola were Haromia axrridis,Coccinella septempunctata,spider and C.septempunctata in Gongliu,Yili,etc.The domaint natural enemies were H.axrridis and C.septempunctata.The natural enemies had following effect on C.juglandicola.3.Predatory effects of dominant natural enemies on C.Juglandicola were different.The predatory effects of H.variegate,H.axrridis and C.septempunctata on C.Juglandicola were fitted well with the Holling-II disc equation,and the predation ability:H.axrridis>C.septempunctata>H.variegate.Temperature affected the predation effect of H.axrridis to C.juglandicola.The maximum daily predation was at 30℃.Intraspecific interference of H.axrridis on C.juglandicol affected the predation.With the increase of the density of H.axrridis,the average predation rate decreased.4.Natural enemies not only have a direct predation effect on C.Juglandicola,but also have an indirect non-lethal effect.Under indoor conditions,the life span of C.Juglandicola under short-term stress of H.axrridis declined,and the reproduction of C.Juglandicola increased.The development period of C.Juglandicola decreased and the production of C.Juglandicola increased under field conditions of H.axrridis in the field.The population growth process was different under long-term stress of H.axrridis in the field.In summary,population dynamics and dominant enemy species of C.juglandicola were inconsistent in different regions.The number of C.juglandicola was the least and the number of enemy was the most in the walnut-alfalfa intercroppingThe predatory effects of dominant enemies were fitted well with Holling-Ⅱdisc equation H.axrridiss had a non-lethal effect on the C.juglandicola,and it was affected by the temperature.