我国甜菜夜蛾间歇性暴发频度的大尺度地理差异及其成因分析

【目的】为探索我国甜菜夜蛾Spodoptera exigua(Hübner)间歇性大暴发频度的大尺度地理差异及其成因,作者研究和分析了我国1956—2008年52年间共发生的121次甜菜夜蛾大暴发频次地理分布的行政区域特征、纬度特征和经度特征。【方法】首先查阅和整理我国历代以来有关甜菜夜蛾记载和研究的文献,并按时间序列方式进行归纳和总结,得出中国1956—2008年52年间共发生甜菜夜蛾大暴发频次为121年次,然后分别按中国省级行政区域、纬度分级区域和经度分级区域进行重新整理分析,在此基础上,进一步细分出中国不同省区及不同经纬度地区甜菜夜蛾有暴发记录的历年总频次数,然后进行统计分析。【结果】分析结果表明:按省级行政区域进行统计,中国有17省(直辖市)有甜菜夜蛾暴发的记录;按暴发频次多少可分为低频暴发区(记录1~4次的共有8省市,即天津1、北京1、海南1、湖南1、云南2、广西3、辽宁3、福建3)、中频暴发区(记录5~9次的共有5省市,即湖北5、安徽7、上海8、江西8、陕西8,占总频次的29.8%)和高频暴发区(记录10次以上的4省市,即山东10、河南13、浙江13、江苏34,占总频次的58%)。按经纬度值进行统计,中国甜菜夜蛾有暴发记录的纬度范围为21.44°~41.97°N,即从中国南部的福建莆田至北部的辽宁抚顺都有甜菜夜蛾暴发的记录,经度范围为107.09°~123.97°E,即从中国西部的陕西关中至东部的辽宁抚顺都有甜菜夜蛾暴发的记录。而暴发最频繁的纬度范围是28°~38°N,约占总频次的89.3%;暴发最频繁的经度范围是113°~121°E,约占总频次的81.8%。【结论】中国甜菜夜蛾间歇性暴发区以华北平原和长江中下游平原地区为主,暴发寄主以蔬菜和棉花为主,暴发季节以7—10月为主。甜菜夜蛾间歇性高频暴发区,其地理特征主要为低海拔地区,即平均海拔低于500 m(也有极少部分发生在平均海拔为1 000~2 000 m之间的盆地);其气候特征主要为暖温带3 400℃≤活动积温≤4 500℃及亚热带地区4 500℃≤活动积温≤8 000℃、湿润(年降水量≥800 mm)及半湿润地区(400≤年降水量≤800 mm)和亚热带及温带季风气候区(该两个气候区的共同特点是夏季高温多雨,冬季低温少雨或寒冷干燥)。

Large-scale geographical variation and cause analysis on the frequency of intermittent outbreak of the beet armyworm,Spodoptera exigua

Objectives] The author explored the large-scale geographical variation in the frequency of intermittentoutbreaks of the beet armyworm, Spodoptera exigua （Htibner） in China, in order to determine the causes of outbreaks. Methods] This was done by analysis of the characteristics of administrative regions, including latitude and longitude, within the geographical distribution of 121 large-scale outbreaks of beet armyworm which occurred in the 52 year period from 1956 to 2008. Results] Records from each administrative region indicate that outbreaks occurred in 17 provinces or municipalities. These were divided into 3 groups based On the frequencies of outbreaks they experienced： low frequency （1 to 4 outbreaks）, regular （5 to 9） and high frequency （10 or more）. The number of outbreaks experienced in low outbreak frequency regions were 1 in each of Tianjing, Beijing, Hainan and Hunan, 2 in Yunnan and 3 in each of Guangxi, Liaoning and Fujian. The numbers of outbreaks in regular outbreak frequency regions were 5 in Hubei, 7 in Anhui and 8 in each of Shanghai, Jiangxi and Shanxi. The regular outbreak frequency regions accounted for 29.8 percent of total outbreaks. The numbers of outbreaks in the high outbreak frequency regions were 10 in Shandong, 13 each in Henan and Zhejiang and 34 in Jiangsu, together accounting for 58 percent of total outbreaks. Outbreaks occurred across latitudes 21.44°-41.97°N, from Putian in Fujian Province to Fushun in Liaoning province. The latitude range of the most frequent outbreaks was 28°-38°N, where almost 89.3 percent of outbreaks occurred. The range of longitudes in which outbreaks occurred was from 107.09° to 123.97°E, which is from Guangzhong in Shanxi to Fushun in Liaoning province. The longitude range of the most frequent outbreaks was 113°-121°E, in which around 81.8 percent of outbreaks occurred. Conclusion] The major outbreak region was the Huabei Plain and the middle and lower reaches of the Yangtze River. The main outbreak hosts were vegetables and cotton, and the outbreak season was from July to October. The main geographical feature of high outbreak frequency areas was low altitude; that is, an average altitude of less than 500 m （a very small proportion of outbreaks occurred in a basin with an average altitude of 1 000-2 000 m）. Climatic characteristics of this area include a temperature range from warm temperate （3 400℃ ≤ active accumulated temperature ≤ 4 500℃） to subtropical （4 500℃≤ active accumulated temperature ≤ 8 000℃）, and moisture range from moist （annual precipitations〉 800 nun） to sub-humid （400 mm≤ annual precipitations〈 800 mm）. High outbreak areas had sub-tropical and temperate monsoon climate zones with hot, rainy Summers and cold, dry winters.