Population Fluctuation And Migration Dynamics Of Rice Planthopper In Hubei

The white-backed planthopper(WBPH),Sogatella furcifera(Horvath)and the brown planthopper(BPH),Nilaparvata lugens(Stal)are major rice pests in both temperate and tropical regions of East and South Asia.The rice planthoppers(RPH)migrate regularly northward in spring and summer and southward in autumn,that cause the huge loss on rice production in several countries,such as China,Vietnam,and Thailand.Hubei Province is located in central China,the middle reaches of the Yangtze River,north of the lake.This province is known as "land of plenty" in the world and is also one of the major rice producing areas in China.Due to its location in the middle of China,it is the northern boundary of the Rice Planthoper(RPH)occurred;it is also the starting station of back migration.So it is an important link in the whole chain of migration.The rice planthoppers occurrence dynamic is different from the area of Anhui,Jiangsu and other regions in the same areas.Now there is few study 'on source areas of rice planthopper in Hubei.So we are not clear on the migration trajectories of rice planthopper.In this study,we showed the distribution of definite mesoscale source areas of WBPH and BPH in Hunan from 2000 to 2013 and focused on its migration processes with multifactorial dynamic space-time analysis.We obtained the following results:1.The temporal and spatial distribution of rice planthoper migration periods in Hubei from 2000 to 2013In this part,we studied the temporal and spatial distribution of rice planthoper migration periods in Hubei from 2000 to 2013.The results were as follows:(1)The occurrence trend of WBPH and BPH were basically the same.But there were also a slight difference between them.The occurrence of WBPH was more than middle in the average in the past 14 years.The occurrence degree was more serious in 2005 and 2012.The occurrence of BPH was also more than middle in the average in the past 14 years.The both situation were very grim.(2)The average of first appearance time of rice planthopper in Hubei was middle to late in May and the average first appearance time of northern Hubei was 10-20d later than southern Hubei.We could not determine whether rice planthoper was seriously occurrence in a year due to the first appearance time.(3)When a year,rice was severe damaged by WBPH,light-trap catches of WBPH would be more than usual,and the first appearance time of WBPH in light-trap catches would be earlier.2.The mesoscale source areas of WBPH in Hubei ProvinceIn this part,we showed definite mesoscale source areas of migrant WBPH from 2000 to 2013 in Hubei.We obtained the following results:(1)The early immigration period of WBPH was appearance from early May to early June;and a large number of immigrations came in July;WBPH both moved in and moved out in August.(2)WBPH immigrated to Hubei mainly from Hunan,Guizhou,Chongqing and some other neighboring provinces,at the same time,some immigrant WBPH were from Guangxi.(3)WBPH from distant source areas were carried towards north by the south Low Level Jet,then clustered and forced to land by wind shear,cyclone and rainfall.Wind speed can usually reached 20m/s when immigration peaks of WBPH.3.Autumn migration of RPH in HubeiIn this part,the source areas of some region in Hubei were analyzed by HYSPLIT.We obtained the following results:(1)The northeasterly wind and east wind at 900hPa altitude in mid to end of September in Hubei were the suitable weather for WBPH migration to Hunan,Chongqing and Guizhou.(2)When the wind speed was larger,WBPH from Hubei can directly migrate to rice areas of Guangxi and Yunnan.A few of WBPH can land directly to the north of Vietnam.(3)In autumn,most WBPH migrated to Hunan,Chongqing and Guizhou by northeast airflow.When the wind speed was larger,WBPH from Hubei could directly migrate to Guangxi and Yunnan.A few of WBPH could land on the north of Vietnam.