Study On The Occurrence And Forcast Technology Of Mythimna Separata(walker) In Jilin Province

Mythimna separate?Walker?is an important migratory pest,widely distributed in China except Xinjiang,causes damage to cultivated crop by migrating from south to north.It can generally go through 2 generation per year in Jilin province,but it could develop into the 3^rdd generation,and caused more serious damage during recent years.Despite lots of reports on,the characteristic occurrence pattern's changing due to variation of climate and cropping system,the research on new situation,especially the presentation of the 3^rd generation,is minimum.A series of monitoring methods were conducted,including radar,investigation in field,leaf disc assays and field-caged,to study the population dynamics,correlation among generations,ovipositon,feeding behavior and so on.A novel forecast method was applied by syndicating radar data of occurrence,climate,meteorology and trajectory analysis.The research contents are as follows:1.The occurrence of the M.separate in Jilin Province.Monitoring sites were set up in Gongzhuling?the Midwest?,Taonan?the Northwestern?and Meihekou?the Southeast?to record the quantity of moth.Migration fastigium appeared from the end of May to the middle of June.In the mid-late July,the second generation of M.separate adult outbroke to peak.Ovipostion period of the migratory adults was from the end of May to early mid-June.The 2^nd generation of larvae occurred from early June to early July,and the 3^rdd generation of larvae occurred in early mid-August.2.The correlation among different generations of M.separate in Jilin ProvinceThe immigration adults was extremely related to the 2^nd generation larvae positively?P<0.01?.There was a significant positive correlation between the 2^nd adult and the 3^rd generation larvae?P<0.01?.The 3^rd generation larvae were significantly positively correlated with the 3^rdd generation adults?P<0.01?.3.Characteristics of oviposition and feeding behaviorThe highest fecundity,88.36%of all eggs laid,was observed from 20:00 to 23:00,significantly more than any other time period?P<0.01?.Adults only laid eggs on barnyard-grass with significantly more eggs?81.98%?being laid on the withered leaf apex of the upper most leaves than on other locations?P<0.01?.No eggs were observed on maize.The results of choice tests show that the 2^nd instar larvae significantly preferred barnyard-grass to to feed instead of maize?P<0.05?whereas the 3^rd–6^th instar larvae significantly biased maize,against barnyard-grass?P<0.05?.?4?There was no significant difference in the amounts of barn-yard grass and maize consumed by the 2^nd instar larvae?P>0.05?.Significantly more barnyard-grass was consumed by the 3^rd instar larvae than maize,but the reverse was true of the 4^th–6^th instar larvae?P<0.05?.Damage to maize crops by M.separate in Jilin Province is primarily due to the oviposition preferences of the 2^nd generation adults,the host plant preferences of 3^rd generation larvae and feeding by older instar larvae.4.A novel syndicated forecast methodThe radar monitoring data were consistent with the data of trapped test.The results of meteorological analysis show that during the migratory period of the 2nd generation adults,the isotherms in the 925hpa Jilin Province are between 22-24°C,and the wind direction in the early stage of migration is mainly due to the southwest wind and south wind which are not conducive to the return of M.separate.Mainly,part of the date in case of rainy weather makes the M.separate unable to take off or be forced to land.Most of the trajectory analysis points are mainly in the area north of the monitoring point.In the later stage of migration,there is a northeast wind that facilitates the return of the M.separate,which makes the M.separate successful.The southwest direction moved back,but at this time most adults have already stranded their own eggs.In summary,the use of scanning insect radar for the monitoring of migratory pests and M.separate has extremely high reliability,which improves the accuracy of predicting and forecasting the M.separate.This study also realized the insect radar from research type to practical type the transformation.