播期对大豆蚜及其天敌种群动态的影响

【目的】研究大豆播期对大豆蚜Aphis glycines Matsumura及其天敌的影响。【方法】试验在2012年、2013年进行,设置了3个大豆播期处理。每周调查播期处理田大豆蚜种群及天敌种类和数量,分析大豆蚜种群数量、种群增长率的时序动态、大豆蚜和天敌的关联度。【结果】不同播期条件下大豆蚜有翅蚜及无翅蚜的种群动态趋势基本一致,有翅蚜蚜量高峰期要早于无翅蚜1周。处理间的大豆蚜田间始见期与终见期随着播期推后而延迟,大豆蚜在田间扩散和消退的时期也随着大豆播期延后。晚播的两个处理高峰期蚜量多于或等于正常播期处理的蚜量。大豆蚜与天敌关联度随着播期的推后而变高。在调查的7种天敌中大豆蚜与异色瓢虫的关联度最高,草蛉、小花蝽和蚜茧蜂也表现较高的关联度。【结论】播期会显著影响大豆蚜的田间始见期和终见期,随着播期的推迟大豆蚜种群高峰期蚜量以及大豆蚜与天敌的关联度都会提高。

Effect of planting date on the population dynamics of the soybean aphid and its natural enemies

Objectives] To determine the influence of planting date on the population dynamics of the soybean aphid （Aphis glycines Matsumura） and its natural enemies. Methods] Soybeans were planted on three different dates and the numbers of aphid and natural enemies on soybean plants were recorded weekly. The population dynamics of apterate and alate A. glycines, the rate of increase and the correlation between numbers of soybean aphids and their natural enemies were analyzed. Results] There was no difference in the population dynamics of soybean aphids between the three planting date treatments. The peak period for alates was earlier than that for apterates. The appearance and disappearance of aphids on soybean plants was delayed by the planting date, as was their general spread and decline. Numbers of aphids on plants with a delayed planting date was more than, or equal to, that of those on plants with a normal planting date. The degree of correlation between aphids and natural enemies increased with planting date. The correlation was highest between aphids and Harmonia axyridis and was also high between aphids and Oruis sauteri, Chrysopa spp., and Aphidiidae spp. Conclusion] Planting date had a strong effect on when aphids appeared and disappeared from soybean plants. Peak aphid numbers and the correlation between aphid numbers and those of their natural enemies increases if the planting date delayed.