粘虫迁飞的种群动态监测与夜间扑灯节律研究

Population dynamics and temporal patterns of abundance of Mythimna separata during migration

【目的】明确北京北部山区粘虫Mythimna separata(Walker)的种群动态和扑灯规律,探索粘虫的早期监测预警技术。【方法】2011年,在北京延庆利用时控开关控制探照灯诱虫器对粘虫的种群动态进行监测,并对整夜诱虫数量自动分时段取样。获得逐日种群动态数据和相关的生物学参数,使用Grads分析粘虫数量与空中风场的关系。【结果】全年诱集粘虫蛾9 699头,单日诱蛾最高1 366头。全年诱蛾可分为3个世代,各个世代种群均由多个高峰组成,并非陆续增加。性比分析发现雌虫数量显著多于雄虫。分时段数据显示粘虫整夜的扑灯节律可分为迁入型、迁出型或本地繁殖型、过境型和迁入迁出混合型。风场分析表明,诱虫高峰与空中风场偏南气流的频率与持续时间高度一致。【结论】北京延庆全年发生粘虫3个世代,二代幼虫造成的危害最大。一代和二代诱蛾数与空中是否存在偏南气流密切相关。雌虫可能具有更强的迁飞能力。对粘虫扑灯节律数据深入分析,可为迁飞种群是否在本地降落繁殖提供参考依据。

[Objectives]To determine the population dynamics ofMythimna separata (Walker)and the temporal pattern of abundance of this pest in the north of Beijing,and to identify better methods for the early monitoring and forecasting of outbreaks.[Methods]Population information was obtained using searchlight traps operated with an exclusive time-switch. After population dynamics information was available,Grads was used to analyze the relationship between catches and the frequency of northward airflow at 925 hPa.[Results]In 2011,a total of 9699 M.separata moths from 3 generations were trapped.The highest number caught on a single night was 1366.Numbers of each generation did not increasing gradually,but rather had a temporal distribution pattern of many successive small peaks.Significantly more females were captured than males.Time-section-samples were used to classify nocturnal catches by searchlight traps into four types;immigration,emigration or local breeding population,stopover,and a combination of immigration and emigration.Peak catches were highly correlated with the frequency and duration of northwards airflow.[Conclusion]There are 3 generations of Mythimna separata in the north of Beijing and larvae of the second generation cause serious damages to local maize crops.Peak captures of moths of the first and second generation are closely related to the frequency of northward airflow at 925 hPa.Females may have a stronger migration capacity.Intensive study of temporal peaks of abundance in searchlight traps of nocturnal, high-flying migrating armyworm moths will provide better evidence of whether the migrating population lands or not.