2019年北京市延庆区草地贪夜蛾种群动态与虫源分析

Population dynamics and trajectory simulation of migratory moths of fall armyworm Spodoptera frugiperda in Yanqing of Beijing in 2019

为了解草地贪夜蛾Spodoptera frugiperda的迁飞规律,于2019年利用高空探照灯和性诱捕器在北京市延庆区开展其成虫监测,借助气象资料和昆虫轨迹模拟方法分析延庆区草地贪夜蛾迁入时的天气背景场,并探究其潜在虫源地分布。结果表明,北京市延庆区于9月9日晚首次性诱到2头草地贪夜蛾成虫,比高空探照灯见蛾时间早2 d。高空探照灯于9月12日首次见蛾,至10月4日最后1次见蛾,共有12晚见蛾,其中9月仅零星见蛾,10月3日晚虫量最多,达21头,当晚雌雄比为14∶7。后半夜诱蛾量占总诱蛾量的75.0%,符合迁入型昆虫的扑灯节律;天气背景场显示,偏南气流和偏北气流均可诱集到草地贪夜蛾,偏南风时段诱蛾量占总诱蛾量的86.1%,明显多于偏北风时段;下沉气流时段诱蛾量占总诱蛾量的91.7%,表明下沉气流利于其降落。轨迹模拟结果显示,迁入种群借助高空运载气流可能来自延庆区以南的山西、河北、河南等省。北京市延庆区是2019年草地贪夜蛾入侵我国的最北端,偏南气流是该虫北迁的主要运载动力,风切变、下沉气流和降水是其迫降的主要天气条件,其迁飞到达延庆区的时间明显晚于在美国到达同纬度地区的时间,且单一的灯诱和性诱都不能准确反应其到达时间,需进一步开展监测研究。

In order to understand the migration of fall armyworm Spodoptera frugiperda and related factors, moth trapping was carried out in Yanqing, Beijing in 2019 by searchlight and pheromone traps.Based on meteorological data from WRF model, the 3-D insect trajectory analysis program and GrADs were performed to illustrate the weather background and original places of migratory moths of S. frugiperda trapped in Yanqing. The results showed that two male adults of S. frugiperda were attracted on the night of September 9, 2019, two days earlier than the date when the first moth appeared in searchlight trap. In searchlight traps, there were 12 nights from September 12 to October 4 when migratory moths of S. frugiperda were trapped, and from then on, no migratory moths of S. frugiperda was trapped. The maximum number of trapped moth of S. frugiperda appeared on the night of October 3, and 14 females and seven males were trapped. The trapped data showed that 75.0% of the trapped moths appeared in late nights, which was in line with the immigration characteristics. The weather background showed that migratory moths of S. frugiperda could be trapped during the southwards and northwards wind;the catches accounted for 86.1% in southwards periods, obviously more than in northwards periods. In addition,91.7% of the trapped moths appeared along with downdraft that contributed to landing. The trajectory simulation showed that the migratory individuals might come from Shanxi, Hebei, Henan and the south of Beijing with the transport of south winds at high altitude. Combined with the information of S. frugiperda from other provinces, Yanqing was the most northern place for the invasion of S. frugiperda in 2019. S.frugiperda was also a windborne migratory insect species and southwards wind was the main transport force. Wind shear, downdraft and precipitation were the main weather factors for its forced landing. The date when S. frugiperda immigrated to Yanqing was significantly later than the arrival time of this species at the same latitude in the United States. The trapping results indicated that neither searchlight trap nor pheromone trap could reflect the time of its arrival accurately, and therefore further research is needed.