刈割对苜蓿主要害虫种群数量动态的影响

在甘肃省定西市九华沟系统研究了刈割对苜蓿主要害虫种群数量动态的影响.结果表明，刈割对害虫种群数量的影响在不同害虫种类之间存在明显差异.刈割对苜蓿斑蚜、豌豆蚜和蓟马的控制效果非常明显.6月初第1次刈割能极显著降低其季节平均数量，并使其保持较低的种群密度水平，7月中旬第2次刈割对其季节平均数量的影响小于第1次刈割.刈割对盲蝽种群的影响有所不同，虽然第1次刈割初期盲蝽的种群数量显著低于未刈割田，但刈割后盲蝽的种群数量回升较快，到8月上旬其种群数量显著高于未刈割田.第2次刈割对其季节平均数量的影响大于第1次刈割.

Effects of cutting on the population dynamics of main insect pests on alfalfa.

A systematic investigation was made on the effects of cutting on the population dynamics of main insect pests on alfalfa in Dingxi of Gansu Province. The results showed that the effects of cutting varied significantly with the kinds of insect pests. The seasonal average population densities of Therioaphis trifolii, Acyrthosiphon pisum and thrips decreased significantly and maintained at a low level under the first cutting in early June, but less variation was observed under the second cutting in mid-July. Plant bug presented somewhat different picture. In the early period of first cutting, its seasonal average population density decreased significantly but increased then, and was significantly higher in early August, compared with that in uncut field. Opposite with T. trifolii, A. pisum and thrips, the seasonal average population density of plant bug was more affected by second cutting.