Effect of parasitization by aphidius platensis brèthes on the developmental physiology of its host, aphis craccivora koch
1959
Johnson, Bruce
Parasitization of nymphs of Aphis craccivora by Aphidius platensis results in interference with their normal developmental physiology. Different stages of growth of the parasite have opposite influences on the host: unhatched parasite eggs exert a “juvenilizing” effect, producing metathetely; whereas parasite larvae sometimes cause the premature appearance of adult characters (prothetely). When winged nymphs of the host are parasitized, the differentiation of alatiform structures is inhibited. This results in the production of aphids intermediate in form between normal alatae and aptcrae; the extent of development of alatiform structures is determined by their degree of differentiation at the time of parasitization and whether one or more parasite eggs are deposited. It is suggested that parasitic metathetely in aphids is brought about by interference with the titre of juvenile hormone, and that alate-apterous polymorphism in aphids generally is controlled by the same hormone system as is concerned in moulting and metamorphosis.
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