Beitrag zur Kenntnis der Bionomie und Morphologie der Hanfblattlaus Phorodon cannabis Passerini, 1860 (Homoptera: Aphididae).

Abstract

Field studies have shown the hemp aphid, Phorodon cannabis Passerini, to be widespread in the German Democratic Republic wherever hemp is cultivated. Mass infestation appaers, however, not earlier than in August because the buildup of the populations is retarted owing to the very small initial occurrence in spring. The oviparus females lay their eggs preferably on the seed capsules of the hemp plants. Cultivated hemp is an annual plant and practically the only host in Central Europe hence host finding is rendered extremely difficult for the hatching fundatrices. On Cannabis sativa Linnaeus fundatrices have been found in the field as well as reared in the insectary. The two generations following the fundatrix contained 78 per cent alatae or more. The oviparous females are the progeny of both apterous and alate mothers. All morphs of P. cannabis are described. They are compared with the corresponding morphs of the hop aphid, Phorodon humuli (Schrank).