Occurrence Regularity, Parasitoid Biology And Eco-Friendly Chemical Control Of Cydia Zebeana

Cydia zebeana,the main pest of larch plantation,mainly endamages the cortex and phloem of basal part of both current-year leading shoot and newborn lateral branches of 3-20 year-old larch. Recent years,it occurred seriously in the young plantation and natural forest.The eco-friendly control technology of cydia zebeana is needed urgently.Occurrence,parasitoid biology,and ecofriendly chemical control of Cydia zebeana was studied.The results are as follows:A survey was conducted at Daxing' anling and Haerbin,to study the damage of Cydia zebeana on larch trees of different ages.C.zebeana mainly endangers the leading shoot of young trees.Gall nummer is significantly higher in the middle-low part than in the upper parts of a crown, while there is no obvious difference in gall nummer between different orientations of the crown.The insect density on the edge of forest is markly higher than that in forest,and the insect density in the mixed forest is evidently lower than that in the pure forest.86.1%and 80.6%of the galls respectively distribute at a diameter interval from 0.4cm to 1.19 cm in Daxing' anling and Haerbin. Young larch forest with lower crown density and more small branches should be controlled principally.Two parasitic enemies of Cydia zebeana were found for the first time—Ascogaster olethreuti and Macrocentrus sp..Biological habit of Cydia zebeana's two parasitoids has been studied.The results showed that Ascogaster olethreuti is solitary parasitism,Macrocentrus sp.is gregarious parasitism.Both of them are koinobiont endoparasitism which parasitize in the two-year larva of Cydia zebeana.They have one generation in one year,which hibernate in two-year larva of Cydia zebeana.The parasitic rate of Ascogaster olethreuti and Macrocentrus sp.is high.Their parasitic rate and its host species is positively correlated.The hightest parasitic rate of two parasitoids is 4.76%and 41.69%respectively.The two parasitoids have good natural control.The behavioral responses of two parasitoids to nine kinds of larch volatiles namely R-α-pinene, S-α-pinene,S-β-pinene,ocimene,phellandrene,3-carene,myrcene,and phyto in a series of concentrations of 0.0004,0.004,0.04,0.4 mol/L had been studied,using Y-tube olfactometer.The results indicated that Cydia zebeana is inclined to several larch volatile to different extent(P＜0.05), but the behavior response of Cydia zebeana to different concentrations have diversity.0.4mol/L R-α-pinene attracted the male,while 0.0004mol/L R-α-pinene repelled the male.Ascogaster olethreuti and Macrocentrus sp.were inclined to several larch volatile to different extent(P＜0.05),0.04mol/L S-β-pinene and 0.0004mol/L phyto attracted the two parasitoids,0.004mol/L phellandrene repelled the two parasitoids.Using these volatiles can control Cydia zebeana,and enhance the location capability of parasitoids. Six Low-toxin Insecticides were used at the peak of emergence period,early stage of hatching period and peak of hatching period.Spraying insecticides one time at peak of emergence period,the control rate of 3000X,4000X,5000X 5%imidacloprid EC and 800X,900X,1000X 3%matrine AS is more than 75.0%;Spraying insecticides two times at peak of emergence period and early stage of hatching period,the control rate of 3000X,4000X,5000X 5%imidacloprid EC and 3000X,3500X, 4000X 3%high permeability fenoxycarb EC was more than 74.0%;Spraying insecticides two times at early stage of hatching period and peak of hatching period,the control rate of 3000X,4000X, 5000X 5%imidacloprid EC and 8000X,9000X,10000X 2%avermectin EC was more than 74.7%. The control rate of different insecticides among three concentrations have no prominent difference(p＞0.05).Several insecticides to natural enemy is harmless.The control rate of different insecticides in different periods have prominent difference(P＜0.05).Each insecticide has little influence with other insecticides for the same tree.Imidacloprid EC,matrine AS,high permeability fenoxycarb EC and avermectin EC could interfere oviposit and larvae hatch of Cydia zebeana if used at the right time.Eco-friendly control technology of Cydia zebeana contains:mixed forest,natural enemy protection,and low-toxin chemistry control.Based on the insect density and natural enemy parasitism,migrating natural enemy or spraying low-toxin chemistry can be used to control the Cydia zebeana.