Incidence and parasitism of insect pests of cruciferous crops in the North Island—evaluation of data, 1955–58 seasons

Abstract

Damage to crucifer crops in Hawke's Bay, Wairarapa, Manawatu, Rangitikei, and Taranaki, during 1957–58, was extremely slight and in most cases confined to margins of crops. Virus disease (symptoms of which are described) caused heavy mortality of white butterfly, Pieris rapae (L.), during the latter part of the season, when parasitism by Pteromalus puparum also reached a high level. The larval parasite Apanteles glomeratus (L.) appears to exercise no control. The diamond-back moth, Plutella maculipennis Curtis, was effectively controlled by the parasites Angitia cerophaga (Gravenhorst) and Diadromus collaris (Gravenhorst), particularly the former. A fungus is also effective in the autumn. Populations of the cabbage aphid Brevicoryne brassicae (L.) were very small in all districts.