Study On The Biology,Risk Analysis And Control Strategy Of Leptocybe Invasa Fisher&Lasalle

Leptocybe invasa Fisher&LaSalle(Hymeoptera:Eulophidae)is the gall-inducing insect and harms eucalyptus trees,which was discovered in the Middle East and Mediterranean countries as early as 2000.According to the current survey,L.invasa can harm 31 eucalyptus trees,and has been added to the object of phytosanitary pests in China.This paper deals with the research results for L.invasa,such as the survival rate under high and low temperature stress in different periods,supercooling point value,the relative expression of HSP70 and HSP90 under high temperature stress,the potential geographic distribution model in China,and using Analytic Hierarchy Process to analyze the preferred control strategy for different ages of eucalyptus trees invaded by L.invasa.The results are as follows:1.L.invasa showed strong heat resistance and cold resistance for short period treatment at the test temperatures.The survival rate was more than 96.67%when they were exposed at 35??42? for 1 hour.The survival rate was more than 90%when they were exposed at-3??-9?for 1 hour.2.The metabolizing process of L.invasa changed with temperatures decreased exponentially.High and low temperatures inhibited metabolism of L.invasa.The life span of L.invasa was shortend to 18 hours when temperature increased to 41 ?,and 30 hours when temperature decreased to-10?.3.The supercooling points of adult and larva L.invasa were-10.92?� 0.24? and-10.39 � 0.30? respectively.The maximum of larva was-7.1?,and the minimum of adult was-14.9?,there was no difference between them.The super-cooling points of both adult and larva showed normal distribution.4.The relative expression of HSP70 in L.invasa tested at 35 ?,37?,39?,41?,42? was,respectively,7.69,8.15,12.01,9.48,2.39 times that of the control group(25?),and the expression of HSP70 reached a peak at 39?.Subsequently,the expression of HSP70 decreased.5.The relative expression of HSP90 in L.invasa tested at 35?,37?,39?,41 ?,42? was,respectively,3.26,5.94,5.36,2.04,1.20 times that of the control group(25?),and the expression of HSP90 reached a peak at 37?.Subsequently,the expression of HSP90 decreased.6.L.invasa generally grew 1?3 generations at most suitable areas in China.The annual development concentrated on 3 generations and more,the majority more than 5 generations in those invaded areas,such as Guangxi,Guangdong,Hainan and Fujian.According to risk analysis,among the 670 potential geographical distribution areas,the safe areas were 257,accounting for 38.56%;the minor danger areas were 189,accounting for 21.21%;the danger areas were 142,accounting for 21.19%;the high risk areas were 82,accounting for 12.24%.7.For young eucalyptus forest,the optimum control strategy of L.invasa was host replacemen,and for mid-aged eucalyptus forest,it was chemical control.The results in fields showed that the effect of chemical control for young eucalyptus forest invaded by L.invasa was not obvious,and the mid-aged eucalyptus forest was more obvious comparatively.