The Preliminary Investigation Of Drosophila Suzukii In Liaoning And The Research Of Its Reproduction Ability

Drosophila suzukii Matsumura is a dangerous pest of raspberry,blueberry,cherry and other soft-skinned fruits.This pest is native to Asia and has spread rapidly in the Americas and Europe since 2008.At present,it has caused serious harm to more than 30 countries.Because it spreads fast,host variety and endanger the health of mature fruits,it has become a quarantine pest on a global scale.D.suzukii was first recorded in China at 1937,but it did not cause serious harm at that time.In recent years,with the expansion of the small berries industry in China,there are more and more reports about the berry pests,especially D.suzukii attacking soft-skin fruits in China.Liaoning is the main planting area of small berries in China,and with the D.suzukii harm countries(Japan and South Korea)approaches,so that D.suzukii's potential risk is more higher.Therefore,it is very important to maintain the safe and sustainable development of fruit industry in Liaoning by identifying the main pest species and occurrence regularities of D.suzukii.The study was conducted between 2014 and 2016,first the quantitative and qualitative analysis of the risk level of D.suzukii in China were analyzed,and then we investigated the occurrence and distribution of D.suzukii,at the last we studied the reproductive charateristicas of D.suzukii.The results are as follows:1.The quantitative and qualitative analysis of the risk level of D.suzukii in China were analyzed in five aspects:the domestic and international distribution(Pi),the potential damaged degree(P2),the economical value of the damage objects(P3),the establish and possibility of later spreading(P4),and the management difficulty(P5).The results showed that SWD was identified to be a high risk pest,according to the synthetical risk value which was 2.12(higher than 1.5).It needs to strengthen the prevention and control of D.suzukii and leaves to control its spread spread2.This study investigated the occurrence of D.suzukii in Liaoning.Sentinel traps were used to monitor D.suzukii adults and suspected fruits were collected weekly in 4 different locations(Shenyang,Faku,Fenghuangcheng,Wafangdian),from June 2016 to October 2016.The results showed that D.suzukii were distributed in the sweet soft-skinned fruits planting areas of Liaoning,Northeast China,and the host plants of D.suzukii were raspberries,blueberries and cherries.The relative abundance of D.suzukii adults captured were 29.37%,28.06%,13.53%,5.68%from Faku,Fenghuangcheng,Shenyang and Wafangdian,and the relative abundance was less than 30%from each survey locations.The weekly average amount of D.suzukii adults captured in each trap were 49.90,38.98,10.17,6.90 from Fenghuangcheng,Faku,Wafangdian and Shenyang.In each location,the amount of D.suzukii adults captured from field was more than that from wood or bush.The change trend of D.suzukii adults were similar in different locations,with one capture peak and decreased to zero.The amount of D.suzukii adults captured increased to the peak at Jul 18-24,Jul 25-31,Aug 1-7,Aug 8-14 from Shenyang,Fenghuangcheng,Wafangdian,Faku.Among the survey locations,the sexratio of D.suzukii adults captured was no significantly different and it was in a range of 75%-95%.The D.suzukii larvae were found in the soft-skinned fruits,such as raspberries,blueberries and cherries.The total amount of D.suzukii.pupae sorted was the most in raspberries and the least in cherry.In Faku,D.suzukii larvae were found in raspberries at the whole of fruiting,and D.suzukii larvae were present in each collected raspberry.Weekly mean the average amount of D.suzukii pupae were increased to the peak and then decreased to zero in raspberries.But in cherries and blueberries,D.suzukii pupae were found in overripe fruits.The wild berries from a total of 10 plant species were collected from non-crop habitats of Liaoning,such as Viburnum dilatatum Thunberg,Cornus controversa Hemsl.ex Prain and Lonicera caerulea L..In addition,we also found that the two kinds of parasitioids,respectively is Leptopilina japonica formosana and Asobara japonica.3.We measured the reproduction ability of D.suzukii which by artificial rearing.Firstly,D.suzukii's oviposition selectivity of 5 species of hosts(raspberry,blueberry,cherry,banana and artificial feed)was studied.The results showed that the reproduction ability of D.suzukii was different for different host fruits.The fecundity of D.suzukii from high to low followed by raspberry,blueberries,cherries,bananas and artificial feed,and the fecundity of D.suzukii of raspberry was significantly higher than other host fruit.In addition,D.suzukii more like to lay eggs on the broken fruits than the complete fruits.Secondly,the supplemental nutrition helps to improve the fecundity of D.suzukii,and causes D.suzukii to start laying eggs earlier.Finally,the preoviposition period of D.suzukii was shortened with increasing temperature,and the oviposition period and fecundity of D.suzukii presents a tendency to first rise and then decrease with incresing temperature.And the fecundity at 25 ? was significantly higher than that at other temperatures,the oviposition period at 22? was significantly higher than that at other temperatures.So the suitable spawning temperature of female adults of D.suzukii is 22-25 ?.