Studies On The Biological And Ecological Characters Of Xylosandrus Germanus And Its Control

Xylosandrus germanus(Blandford) is a new pest attacking grapevine.It is one of ambrosia beetles that can apparently attack healthy plants.It has been found attacking grapevine in china since 2003,and serious economic loss has been reported.To control the ambrosia beetle effectively,the biological and ecological characters and its control were studied,and the results are as follows:1.The biological characters of the bettle was studied by observing and monitoring the females' flight activity by Lindgren Funnel traps in field,the adult females being reared on grape logs and semi-artificial diets,and the lavare also being reared on the PDA plates inoculated with A.hartigii.The adult females mainly infested trunks of grapevine.It had 3-4 generations per year in Chengdu region,and overwintered as the adult females at the base of the grapevine in the last ten-day of November.The overwintering adults' flight activity began in March and continued until May.There were two flying peaks in field. The sex ratio was 10 female:1 male.The developmental time of egg,larvae and pupae were 5.6,10.7 and 6.3d at 25℃,respectively.2.The spatial distribution pattern of Xylosandrus germanus was studied by investigating the distribution of the female adult entrance holes in grapevine.The fitting test for spational distribution,analysis of the aggregative indexes,the Taylar's law and Iwao regression all showed that the spatial distribution patterns of the entrance holes fitted the negative binomial distribution and belonged to the aggregated pattern both in orchards and within trees,the basic element for the distribution was clusters of individuals both in orchards and within trees,and the individuals attracted each other.Therefore,aggregative attacking strategy was used by the pest to conquer the host plants.3.Take-off activity of the adult females of Xylosandrus germanus was studied in lab.A relative remarkable phototaxis of the beetle was proved.In the region of light intensity between 1-400 lx,the phototaxis of the beetle increased with light intensity.At temperature of 25℃,no beetle took off in the dark,the rate of take-off of the female adults increased with light intensity in the region of light intensity between 1-1500 lx and 1500 lx for maximum flight.At light intensity of 4001x,the rate of take-off of the beetle increased with temperature in the region of temperature 21-30℃,21℃was minimum for flight and 25-27℃for maximum flight,while flight activity ceased at temperatures over 35℃.These results showed that the female adults preferred low light intensity for flight,the threshold temperature necessary for flight was 21℃,and temperature was prerequisite for flight initiation.4.When the overwintered adult females came out of galleries,it was the key measure to control the beetle with contact-active insecticides.The control efficacies of 2.5% lambda-cyhalothrin(EC),48%chlorpyrifos(EC) and 52.25%Nurelle-D505(EC) against the beetle attacking grapevine were evaluated in field by spraying and brushing the mink. 2.5%lambda-cyhalothrin(EC) at a dilution of 1:2500,48%chlorpyrifos(EC) at a dilution of 1:2500,and 52.25%Nurelle-D505(EC) at a dilution of 1:1500 were sprayed. Three insecticides were all brushed at a dilution of 1:100(insecticide:water plus earth). Then,the minks were covered with nylon net.The results showed that three insecticides all had a good control effect against the overwintered female adults during 1-7d days after application whether sprayed or brushed on the trunk.Of three insecticides,52.25% Nurelle-D505(EC) maintained better control effect against the overwintered female adults during 13 days by brushing.The following measures should be taken for control the Xylosandrus germanus:1)Strengthen the growing management of grapevine in order to stregthen the vigor of the grapevine for resist;2) Once the grapevine attacked by the beete are found in the orchard,these trees should be cleared and burn out immediately;3) It is the key measure to control the overwintered adult females with contact active insecticides.During March to May,the contact active insecticides are used to spray or brush the trunks every 10-15 days.4) During the growing season of the grapevine,put the cotton ball which had been dipped into the DDVP at a dilution of 1:50 into the entrance tunnels to kill the beetles when a few beeltes attack the grapevine.The folIowing measures should be taken for controlling Xylosandrus germanus:1) Strengthen the field management of grapevine in order to enhancing the vigor of the grapevine;2) Once the grapevine attacked by the beete are found in the orchard,these trees should be cleared and burn out immediately;3) It is the key measure to control the overwintered adult females with contact active insecticides.During March to May,the contact active insecticides are used to spray or brush the trunks every 10-15 days.4) During the growing season of the grapevine,put the cotton ball which had been dipped into the DDVP at a dilution of 1:50 into the entrance tunnels to kill the beetles when a few beeltes attack the grapevine.