Effect of planting date on the population dynamics of the soybean aphid and its natural enemies
Author of the article:XIA Ji-Xing YANG Fan LIU Yu LI Xin-Min XU Wei-Jun***
Author's Workplace：Plant Protection Institute, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
Key Words：Aphis glycines, planting date of soybean, natural enemy, dynamic of population, correlation degree
Abstract： [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.