桃蚜、萝卜蚜的种内密度和种间竞争效应

在温室内不同密度条件下，研究了桃蚜和萝卜蚜在甘蓝上的种内密度效应和种间竞争作用。结果表明：单独饲养时，在5头／株和10头／株密度下，两种蚜虫种内密度效应均较弱；而在15头／株时，桃蚜和萝卜蚜的寿命和产蚜量都随之显降低，说明当两种蚜虫达到一定的拥挤程度时，种内密度对种群均产生一定的负效应。两种蚜虫共存时，单头产蚜量均比单独饲养时显下降，种问竞争作用明显。在10、15头／株密度下，桃蚜的竞争作用大于萝卜蚜，萝卜蚜的寿命和单头产蚜量都极显低于桃蚜。

Intra-and interspecific relationship of Myzus persicae (Sulzer) and Lipaphis erysimi (Kaltenbach) on cabbage

The intraspecific and interspecific relationship of Myzus persicae and Lipaphis erysimi on cabbage were studied under the conditions of greenhouse. The density-dependent effects of M.persicae and L.erysimi were weak at the density of 5 and 10 aphids per plant; longevity and progeny of this two species of aphids at the density of 15 aphids per plant were significantly lower than that of the density of 10 and 5 aphids per plant. The negative density-dependent effect was observed in this two species of aphids. The fecundities of M.persicae and L.erysimi were significantly higher when reared alone than that when reared toghter, indicating that the population of this two species of aphids was affected by interspecific competition. Longevity and progeny of L.erysimi were significantly lower than that of M.persicae when they reared together at the density of 10 and 15 aphids per plant in each species, indicating that the interspecific competition of L.erysimi was less than that of M.persicae.