Hyperparasitism of the Pea Aphid Parasite Aphelinus semiflavus1 by Asaphes vulgaris2 in a Green house3

Abstract

While large numbers of the pea aphid, Acyrthosiphon piston (Harris), were being reared on peas, broad beans, and alfalfa in a greenhouse (18–21°C) at Kentville, for feeding Coccinella septempunctata L., during the autumn of 1967, a primary parasite, Aphidius pulcher Baker (= pisivorus Smith) was accidentally introduced. This parasite pupates within a light–tan-colored globular mummified pea aphid. Shortly afterward, Asaphes vulgaris Walker,4 a common secondary parasite of A. pulcher in the field in Nova Scotia, began to increase in numbers, predominantly on the broad beans and peas. During January, dark, flattened mummified pea aphids from which Aphelinus semiflavus Howard5 adults emerged, appeared on the alfalfa foliage. A sample of 100 mummies was individually reared in plastic culture tubes in the laboratory. The emergence was: A. semiflavus 56, A. vulgaris 12, and nonemerged 32.