Abstract
The life cycle of Aphis nerii and its natural enemy complex were studied at two hedges of Nerium oleander var. indicum in Kyoto in 1990-1993. A. nerii overwinters parthenogenetically in Kyoto, with a dormant period of about 2 months beginning early February. It starts to disperse in early May and then follows a typical seasonal abundance trend with two major peaks in early June and early August, and a minor peak in September. From October on, outbreaks occur only if plants are pruned in autumn. Fifteen aphidophagous species composed of Coccinellidae (3spp.), Syrphidae (4spp.), Chamaemyiidae (1sp.), Chrysopidae (3spp.), Hemerobiidae (1sp.), Aphidiidae (2spp.) and Aphelinidae (1sp.) feed on A. nerii. From late May to mid-September, Cheilomenes sexmaculatus is the aphid's major natural enemy. The rapid decline in A. nerii populations after the first and second peaks are attributed mainly to predation by this coccinellid. From late September on, syrphids and parasitoids, particularly Aphelinus sp., become dominant predators. However, these insects appear to have little effect on A. nerii populations. The toxicity of this aphid to its natural enemies is discussed.
