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.