季风进退和转换对中国褐飞虱迁飞的影响

Abstract

Based on the daily reanalyzed meteorological dataset of the National Center of Environment Predicting(NCEP) in USA and the pentadly lighting catches of brown planthoppers(BPH) in China,in this paper,the temporal and spatial relationship between the selected monsoon index and the immigrations of BPH was investigated to explore the influence of monsoon advancing,retreating and conversion on the immigrations of BPH in China.The results showed as follows:(1) The middle ten days and the last ten days of March in a year is a conversing period from the north monsoon to southwest monsoon and the first large-scale migration northward of BPH′s populations occurs in the first ten days of April after the beginning of the southwest monsoon.The main landing regions of BPH′s populations in this large-scale migration northward are the rice-growing regions in the South and the Southwestern China.Then,the BPH′s populations migrate to the other northern parts subsequently.(2) From the middle ten days of June to the middle ten days of August in a year,the south monsoon index reach its maximum of the positive values while the migrations northward of BPH occur most frequently,the populations land in the all four main rice-growing regions,the peaks and landing heads of BPH′s immigration northward amount to the summit.(3) From the last ten days period of August to the middle ten days of September in a year is a conversing period from the south monsoon to the north monsoon and it is the ending period of BPH′s immigration northward and the beginning period of the immigration southward.The first large-scale migration southward of BPH′s populations occurs in this period and the main landing regions are the rice-growing regions between the Yangtze River and the Huaihe River and the rice-growing regions between the Yangtze River and the Nanling Mountain.(4) From the last ten days of September to the middle ten days of October is the strengthening period of the north monsoon and the weakening period of the south monsoon and it is the peak period of BPH′s immigration southward of all rice-growing regions.(5) In the last ten days of October,the south monsoon begins the evacuating from the mainland of China and the north monsoon begins controlling the mainland and the ending dates of BPH′s immigrations appear in each rice-growing region successively from north to south.(6) In the years of BPH′s abnormal occurrence,the sooner or later advancing northward of the southwest monsoon decided on the beginning dates of BPH′s immigration and the expanding southward some time or later of the north monsoon determined the ending dates of BPH′s immigration coming earlier or later.(7) The beginning date of BPH′s immigration falled behind the change of the southwest monsoon and the ending date of immigration lagged behind the change of the north monsoon and their delaying times were 5 to 15 days.