Aphid infestation and virus infection of peas and beans on the Central Tablelands of New South Wales

Abstract

Field Studies were made of aphid infestation, population behaviour and virus incidence on Pisum sativum, Vicia faba and Phaseolus vulgaris at Bathurst, New South Wales, from November 1969 to June 1970. The relative importance of the aphids Aphis craccivora, Macrosiphum euphorbiae, Myzus persicae and Aphis gosypii as vectors of subterranean clover stunt virus (SCSV) and bean yellow mosaic virus (BYMV) was obscured by the overwhelming incidence of A, craccivora. On the first two plantings, virus incidence exceeded 90 per cent and yields were almost nil. Virus incidence was low on peas and canning beans on the third planting. Late infection on broad beans was 82-96 per cent. BYMV incidence, negligible on the first two plantings, was 16 per cent on the third planting of broad beans. Migrating alate aphids were trapped and tested on subterranean clover; c. 10 per cent of A. craccivora carried SCSV, and about 10 per cent of M. eybhorbiae, late in the season, carried BYMV. Three species of coccinellids attacked A. craccivora but did not control aphids until plants matured. Spraying with fenitrothion reduced aphid populations in control plots but had little effect on virus incidence and greatly reduced coccinellids. Aphidiid parasites were few and had little effect on aphid populations.