The incidence of parasitism and disease in some populations of the cabbage aphid (Brevicoryne brassicae L.) in New Zealand

Abstract

The incidence of parasitism in field populations of the cabbage aphid (Brevicoryne brassicae L.) over several seasons wa:.; frequently low. Rearing of field-collected material showed that three secondary parasites, Charips brassicae (Ashm.), Lygocerus niger (How.), and Pachyneuron sp. (?siphonophorae (Ashm.)), were associated, at various levels, with the primary parasite Diaeretiella rapae (M'Intosh). Incidence of the entomophagous fungus Entomophthora aphidis Hoffman reached a significant level only during the autumn population peak of the aphid.