大豆蚜自然天敌种群动态及其控蚜作用研究

The population dynamics and control effect of important natural enemies of the soybean aphid, Aphis glycines

2008-2010年间,分别在辽东山区和辽西半干旱丘陵地区设置试验田,采用系统调查的方法,对大豆蚜Aphis glycines Matsumura自然天敌种群动态及控蚜作用进行研究。共鉴定辽宁地区大豆蚜天敌7目、16科、44种,其中优势天敌异色瓢虫Leis axyridis(Pallas)居首位。田间试验结果表明,大豆蚜天敌田间消长表现连续6个阶段,即初见期、波动期、上升期、盛期、下降期和消退期;田间3年平均大豆蚜数量与天敌(天敌单位)总体呈极显著的相关关系,各年度百株蚜量与天敌单位也均呈极显著相关关系。辽东地区天敌跟随紧密并随蚜虫数量变化波动,具有明显的自然控蚜作用。其中,7月11-21日天敌发生盛期与蚜虫高峰期吻合,蚜虫急剧下降;7月下旬后,受高温、多雨、蚜霉菌作用、植株老化等影响,蚜虫种群逐步下降、消退,天敌也陆续迁出豆田。辽西地区天敌迁入豆田比蚜虫晚10～15d,对前期蚜虫控制弱,且天敌峰期滞后蚜虫5d左右,一般年份蚜虫发生较重。

The population dynamics and the control effect of important natural enemies of the soybean aphid were systematically investigated during 2008 to 2010 in mountain regions of eastern Liaoning Province and semi-arid hill regions of western Liaoning Province, China. Forty four species of natural enemies from 16 families and 7 orders were identified, among which Leis axyridis （Pallas） was the dominant species. The results of field experiments indicate that populations of important natural enemies of aphids in soybean fields went through six consecutive stages; initial, fluctuating, rising, peak, declining and subsiding. Significant positive correlations were found between the mean population size of soybean aphids and overall numbers of their natural enemies in three years. A significant sub-annual correlation was also found between the overall number of natural enemies and the aphid population per 100 plants. In eastern Liaoning, the population dynamics of natural enemies fluctuated closely with those of soybean aphids, suggesting that the former had a significant controlling effect on the latter. The population peaks of natural enemies and soybean aphids were well matched from 11 to 21 of July, resulting in a sharp decline in soybean aphids after that period. After late July, soybean aphid numbers declined gradually due to high temperature and rainfall, fungal infections and plant aging effects which caused their natural enemies to progressively move out of soybean fields. In western Liaoning, natural enemies moved into soybean fields 10 to 15 days later than soybean aphids and consequently had a relatively weak controlling effect on early soybean aphids. Populations of natural enemies also peaked about 5 days later than that of the soybean aphids resulting in relatively serious infestations of soybean aphids in this region.