| Due to differences in body size and flight ability of different insect species,different behavioral strategies will be adopted to maximize the transfer revenue.Small insects use a single,uninterrupted move,while large insects use multiple nights to migrate continuously.At the same time,there are significant directional behaviors in large insects.Migration is the result of long-term adaptation of insects.Therefore,it can be speculated that:The different migration strategies are the result of insects' long-term adaptation to the spatial and temporal characteristics of atmospheric environment according to their own flight ability.In this paper,the differences between the strategies and the characteristics of the atmospheric environment were compared and analyzed so as to verify the above inference.The Armyworm,Brown plant hopper and white-backed plant hopper are important migratory pests that affect rice production in China.To clarify the differences and causes of the migration of three kinds of insects not only can help to understand the relationship between evolution and atmospheric environment,but also could provide the theoretical basis for the prediction and prevention of this three kinds of agricultural pests above.In the same migration environment of east Asian,in order to clear the difference of time and range of migration and explore how they use their own conditions to choose different migration strategies to form a regular migration.In this paper,the light catches data and meteorological data of four sites in Feicheng,Zhangqiu,Jingjiang and Huizhou were selected from 2003 to 2013 for research(Feicheng,zhangqiu represent the armyworm site,Jingjiang,Huizhou represent Brown planthopper and White-backed plant hopper site).The main research methods include WRF model simulation,trajectory analysis,Watson-Wheeler test,t test and other methods to analyze the first north migration process of the three pests in spring.Now compare the difference between different schemes(A:not considering the self-flying speed of armyworm,Brown planthopper and White-backed planthopper;B:consider the speed of their own flight speed;C:consider the speed of their own flight speed and drift angle)of the end distance and the drift angle so as to clear the different migration strategies of the three pest above.The main results were as follow:(1)The peak days distribution of the Armyworm during the first migration period in spring was more orderly and concentrated while Brown planthopper and White-backed planthopper were more dispersed.(2)The meteorological conditions of the three migratory pests above in the peak period were stable.However,there is a certain difference in the meteorological conditions between the Armyworm and the rice planthopper,which the wind direction was more broad(182.08±29.79°)and the wind speed was small(6.76±0.17m/s)while the wind direction of Brown planthopper and White-backed were more concentrated(233.99±19.76°)and the wind speed were greater(9.61±0.33m/s).But what's interesting for Armyworm has:Migration speed=wind speed+its self-powered speed?6.76m/s+3.5m/s=10.26m/s;It is similar to the flying speed of rice planthopper.(3)The distance of the third nights of the Armyworm under A-B and A-C is about 245.51±7.53km and 251.14±7.47km while the Brown planthopper and White-backed planthopper were 33.7±1.83km in 36h.It shows that the Armyworm could better utilize its own fly speed to maximize the flight distance during flight.However,the average distance between the B-C schemes was found to be only about 60.17±4.09km and the angle only have 7.13°.This shows that the self-directed behavior of the Armyworm does not effectively modify its own migration trajectory to expand the range of migration,and the directional behavior may only to keep it in the correct direction of migration. |
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