Effect Of Environmental And Meteorological Factors On The Outbreaks Of The Oriental Migratory Locust In Henan Province

By the use of 1950-2000 data of population dynamics of the Oriental Migratory Locust (Locusta nugmtotia mantfmsu Meym) in Henan Province, and the data of environmental and meteorological factors in the same district, it is studied that effects of environmental and meteorological factors on the locust, and found a way to identify the severity degree of plague. Some results showed as follows.(1) It was found that the time series of outbreak of the locust in Henan Province was stochastic sequence using the way of time series analysis. The degree of the outbreak of the autumn locust had more fluctuant that of summer locust.(2) Contrasting the catastrophe analysis of climate in henna with that of outbreak of the locust, it showed that the outbreak of the Oriental Migratory Locust is strictly connected with environmental and meteorological factors, and climate change may be one of the reasons on the frequent plagues.(3) The study on effects of environmental and meteorological factors on the locust by the key time method, it showed as follows ?㏕here would be an plague of the Oriental Locust in the year after the higher relative sunspot numbers. ?However, El Nino and La Nina episodes had no obvious effect on the outbreak of the Migratory Locust.?Less precipitation than usual in April (drought) was one of the main derivational factors, which caused plagues of the pest. Moreover, the mean area rainfall in April played more important role in the outbreaks of the summer locust than that of the autumn locust. ?There was a new concept 梩he optimum rainfall. It would be advantageous to become a plague when the rainfall was in the range of the optimum rainfall. There was a larger scope of the optimum rainfall of autumn locust than that of summer one. ㏕he mean temperature on the high side in the last November also contributed to the outbreaks of the summer locust in this year.﹖he laws of the outbreak of pest would had been changed as a result of locust control.According to the principal component analysis on the data of the pest, results showedthat density of locust eggs, the area of the remains of last autumn locust, the area of the maximum density about summer locust and the area of the outbreaks of summer locust are die four factors which expressed the extent of the outbreaks of summer locust. However, the autumn one needs three factors, that is, the density and the area of the remains of last autumn locust, and the area of the outbreaks of autumn locust. The scores of the first principal component may approximately represent the extent of the outbreaks of pest. Therefore, a comparatively objective method was found to identify the extent of the outbreak of the pest.