The Ecology of Myzus persicae

This review has been suggested by the Scientific Committee of the In­ ternational Biological Programme as part of a project on the population dy­ namics and biological control of Myzus persicae. In order to contain this review within a reasonable number of pages, information on transmission of virus diseases is virtually omitted; it could easily form a review of equal length. Work on other aphids which is relevant to the ecology of M. persi­ cae has been included in sections where knowledge of M. persicae is lacking or inadequate. A few insect species seem very well adapted to exploit the ephemeral crop environment. They include some aphid species of regional (Aphis fabae, A. gossypii, A. craccivora and Rhopalosiphon maidis as well as other grass aphids) or of almost world-wide importance (Brevicoryne brassicae, Macrosiphum euphorbiae, Myzus persicae) (2). M. persicae is outstanding in distribution, in host plant range (57, 67, 81, 103,148, 149,221,389,422,428,432,444, 525), and as a pest which causes not only direct damage but is able to transmit over 100 virus diseases of plants on about thirty different families including many major crops such as beans, sugar beet, sugar cane, brassicas, potatoes, tobacco and citrus (281). The use of chemical methods to prevent spread of viruses by controlling their aphid vectors has been either unsuccessful or only partially successful. Thus, there is a special need for the integrated control approach which will lower the numbers of the vector especially at times when viruses are spread. Control of the aphid by natural enemies in the noncrop or alternative crop habitat is therefore particularly important, but biological control by natural enemies and by manipulating the host plant could also be enhanced in the crop. Although there is a large background of knowledge on the biology of natural enemies of aphids, their significance in control in both the funda­ mental and applied senses is little understood, except perhaps for Thel'­ ioaphis maculata in California. Quantitative effects of natural enemies and of other factors which help to regulate numbers are partly understood for a few aphids (A. fabae, B. brassicae) during periods when they are pests on crops, but little relevant data is available for M. persicae. Even less atten-