RESISTANCE TO CABBAGE APHID (BREVICORYNE-BRASSICAE) IN 6 BRASSICA ACCESSIONS IN NEW-ZEALAND

The literature concerning the breeding of brassicas resistant to cabbage aphid (Brevicoryne brassicae L.) and the interaction between different cultivars and various populations of the insect is reviewed. Six Brassica accessions selected for their different responses to a population of Brevicoryne brassicae in England were tested in the glasshouse against three New Zealand populations of the insect. All six brassicas were also tested in the field at Lincoln, New Zealand. Under caged conditions in the glasshouse accessions of Brassica fruticulosa Cyrillo and B. spinescens Pomel were shown to have high levels of antibiosis resistance to all three aphid populations expressed in terms of low production of young. In the field, very few aphids settled on the plants of these two Brassica species demonstrating high levels of antixenosis (non-preference) resistance. The cabbage 'Derby Day' and New Zealand rape 'Rangi' supported a rapid increase in aphid populations in the glasshouse and were heavily infested in the field. A collard cultivar 'Green Glaze Glossy' was heavily infested in the field but proved to possess partial levels of resistance in the glasshouse tests. An accession of B. insularis Moris was non-preferred in the field and possessed a level of antibiosis resistance similar to the collard. There was no evidence of the existence of cabbage aphid biotypes to overcome resistance in the three populations studied.