Kunming Institute of Zoology, Academia Sinica, Kunming, Yunnan (China).
A comparison of intrinsic rates of natural increase of the populations of woolly apple aphid, Eriosoma lanigerum (Hausm.) was studied during different seasons in Yunnan province of China. Their r values determined under given experimental conditions were 0.139, 0.1542, 0.2647 and -0.0591 for spring, summer, autumn, and winter populations, respectively. The negative growth of winter population was probably relevant to temperature and poor nutritional condition of apple twigs. The r values of summer and autumn populations showed that apple twigs during summer and autumn could support higher growth rates as compared to spring twigs. However, the highest peaks of aphid natural population occurred in April or May. This could be due to atmospheric temperature and rainfall. Rainfall, perhaps, was of special significance to natural population size during aphid growth season, while natural enemies had relatively less effect on it.
