Effects Of Seasonal Atmospheric Circulation On Northward Migration Of White-backed Planthopper In Spring And Summer

Insect migration is a comprehensive reflection of the biological and environmental characteristics of insects and an important life-history strategy for insects.Seasonal atmospheric circulation is a large-scale migration of air,often covering tens of thousands of square kilometers below or even a large part of the Earth.Some meteorological factors and phenomena have significant effects on the wind-driven migration of insects.In particular,wind and rainfall have a great impact on migrating insects.The Western Pacific Subtropical High(WPSH)is the most important semi-permanent climate affecting China’s meteorological conditions.Recent studies have shown that the northward migration of brown planthopper in summer is related to the intensity and location of the WPSH and its associated wind and rain patterns.At the same time,compared with the brown planthopper,the white-backed planthopper(WBPH,Sogatella furcifera(Horvath))has similar feeding habits,similar body shape and strong long-distance migration ability,so it can be inferred that the white-backed planthopper has similar migration patterns.However,there are few descriptions of long-term migration patterns of white-backed planthoppers and how they relate to climatic conditions.1 The northward migration of WBPH in spring and summer in China is significantly correlated with the WPSHAccording to the data of nearly 30 years(1977-2003),it shows that WBPH come to South China in April with the southwest airflow every year.With the slow northward movement of the WPSH,the southwest airflow gradually strengthened and maintained the northward movement,and South China also entered the Pre-flood season.Although there are suitable wind fields to enable the WBPH to move to the middle and lower reaches of the Yangtze River,it is difficult for the WBPH to move out or have a short distance migrating because of frequent and heavy rainfall during the preflood season.In this period,the WBPH in South China mainly migrated to the eastern coastal provinces and cities,such as Zhejiang and Fujian.Until the middle and late June,after the first abrupt jump of the WPSH,the rain belt moved to the middle and lower reaches of the Yangtze River,the southwest wind strengthened and moved northward.As a result,the WBPH moved into the middle and lower reaches of the Yangtze River under the weather condition.In late July,after the second northward jump of the WPSH,the WBPH moved into the Huaihe River Basin.2 The northward migration of WBPH in spring and summer in south China is hindered by the Preflood seasonIn addition,South China is one of the most important areas of WBPH in China.It is the first station for WBPH when they come to China,which affects the occurrence of WBPH in the later period of China.Thus,the preflood season in South China not only affects the rainfall situation in South China,but also affects the northward migration of WBPH in China.During the period from mid-May to mid-June,the amount of insects in South China was significantly correlated with rainfall(R2=0.54,p<0.005).The more accumulated rainfall in the relevant area,the more insects in South China.Moreover,when the migration distance of WBPH was calculated from May 16 to June 15,it was found that the migration distance of WBPH was shorter than the period when it is in Pre-flood season.Otherwise,with the increasing of distance,the volume of WBPH is reduced quicker.The purpose of this study was to explore the migration dynamics of WBPH in eastern China in spring and summer on a long time scale,to clarify the migration regularity of WBPH,and to explore the corresponding meteorological conditions of WBPH in a large scale and in a long time scale.It is not only helpful to understand the occurrence and development of WBPH in China,the ecological adaptability and evolutionary significance of insect migration,but also helpful to forecast,warn and implement targeted control measures for white-backed planthopper.