Abstract

The impact of infestation by bluegreen aphid, Acyrthosiphon kondoi, cowpea aphid, Aphis craccivora, and/or green peach aphid, Myzus persicae, on grain production of narrow-leafed lupin (Lupinus angustifolius) and yellow lupin (Lupinus luteus) was assessed at 4 sites in the Western Australian grainbelt. Yield losses caused by naturally occurring aphids on 4 cultivars of narrow-leafed and 2 cultivars of yellow lupins were measured by applying the systemic insecticide imidacloprid as a seed dressing and/or as foliar sprays throughout the plant growth phase and compared with untreated control plots. The extent of damage caused by aphids varied greatly but was significantly influenced by lupin cultivar, and yields for the same treatment combination varied between geographical locations. Bluegreen aphid was the most abundant species wherever large colonies of aphids developed. Yellow lupin Wodjil was the most infested and suffered severe losses in grain yield, whereas narrow-leafed lupin Kalya was largely resistant to aphids and there were negligible losses in grain production from plots not treated for aphids. In a fifth experiment, a single foliar spray of the insecticide pirimicarb controlled abundant aphids and increased yield by as much as 95% (0.65 t/ha) in Wodjil. Lupin growers need to be aware of the potential losses aphids can cause and that applying foliar insecticidal sprays to susceptible cultivars can prevent such losses.