广西玉米主要种植区草地贪夜蛾发生及为害情况调查

【目的】明确草地贪夜蛾（Spodoptera frugiperda）在广西玉米主要种植区的种群动态及发生为害规律，为草地贪夜蛾周年繁殖区和其他玉米主产区草地贪夜蛾的预测预报和精准防控提供科学依据。【方法】2020年在广西崇左市、南宁市和河池市选择7个固定调查监测点，采用对角线五点取样法，在玉米生长期每隔7 d调查草地贪夜蛾幼虫数量及对玉米植株的为害特征，计算植株受害率和百株虫量；在7个调查监测点各放置2组桶型诱捕器和诱芯，每隔7 d调查记录1次诱虫情况，统计成虫数量。【结果】各调查点草地贪夜蛾幼虫发生量春秋季各有1次高峰，春秋季百株虫量最高值分别为35.00头和64.67头，秋季虫量明显高于春季。幼虫发生动态呈区域性差异，崇左市扶绥县、南宁市江南区和武鸣区幼虫发生期较短且集中，3个点春季百株虫量和峰值均较高。玉米各生育期均受幼虫为害，苗期以低龄幼虫为主，开花期和成熟期以5~6龄幼虫为主，其他生育期可见各龄期幼虫，世代重叠明显。各调查点春季草地贪夜蛾成虫数量总体上呈抛物线增加趋势，春季每诱虫桶最高虫量为25.33头；秋季虫量呈波浪状，约21 d出现一次峰值，每诱虫桶最高虫量为34.67头；秋季成虫数量总体上高于春季。【结论】草地贪夜蛾在广西全年均可发生，年发生代数在7代及以上，秋季虫量明显高于春季，发生程度随温度升高而加重。幼虫发生期和虫量存在区域差异，幼虫可为害各生育期玉米。草地贪夜蛾严重为害玉米生长，应进一步加强监测预报，根据区域气候和玉米长势，强化低龄幼虫和成虫高峰期的防控力度，以降低草地贪夜蛾造成的危害。

Investigation on the occurrence and damage of Spodoptera frugiperda in the main maize production areas of Guangxi

【Objective】In order to provide scientific reference for forecast and precision control of fall armyworm, Spodoptera frugiperda in its year-round breeding area and other main maize production regions of China, the population dynamics and damage of fall armyworm in the main maize-growing areas of Guangxi were investigated.【Method】Seven fixed monitoring and investigation points were selected in Chongzuo, Nanning and Hechi in 2020. The number of fall armyworm larvae and its damage characteristics to maize were investigated every 7 d during corn growing season by the diagonal five-point sampling method, the damage rate of plants and the number of larvae per 100 plants were calculated. Every two barrel-shaped traps with sex-induced cores were placed in the seven fixed monitoring and investigation points respectively, then the trapping situation was investigated and recorded every 7 d, the number of fall armyworm adults was counted.【Result】The occurrence of fall armyworm larvae in each investigation point peaked once in spring and autumn respectively. The highest number of larvae per 100 plants in spring and autumn were 35.00 and 64.67 respectively. The number of larvae in autumn was higher than that in spring. The occurrence dynamics of larvae differed from region to region, the larval emergence period in Fusui of Chongzuo, Jiangnan District and Wuming District of Nanning was short and concentrated, the number of larvae per 100 plants and the peak value of the three points were higher. Fall armyworm larvae could damage all growth stages of maize. The seedling stage was damaged mainly by young larvae, while the flowering and maturity stages were damaged mainly by 5th-6th instar larvae. Various instar larvae damaged other maize growth periods with overlapped generations. The number of fall armyworm adults in spring showed a parabolic increase trend in each investigation point with a maximum value of 25.33 adults per barrel-shaped trap. The number of adults in autumn fluctuated with a small peak every 21 d, and the maximum value was 34.67 adults per barrel-shaped trap. The number of adults in autumn was generally higher than that in spring.【Conclusion】Fall armyworm can occur throughout the year in Guangxi with no less than seven generations per year. The number of fall armyworm in autumn is obviously higher than that in spring, and the degree of occurrence increases with temperature. Region-specific differences are observed in the occurrence period and number of larvae. Maize can be damaged by fall armyworm larvae at different growth stages. Fall armyworm seriously damages the growth of maize, so the monitoring and forecasting should be strengthened. The prevention and control of young larvae and adults in peak period should be strengthened according to the growth of maize and the regional climate to effectively reduce the damage caused by fall armyworm.