Acyrthosiphon pisum (pea aphid).

Abstract A. pisum is a major pest of pea, lucerne and clover. Severe damage can occur to peas due to direct feeding and virus spread. Direct feeding on pea results in sap being removed from terminal leaves and the stem. Heavy infestations on pea can cause stunting, deformation, wilting and even death. Plants smaller than 15 cm can easily be killed by aphid infestations, although plants bigger than 15 cm usually suffer only relatively minor damage due to direct feeding. Aphids can also feed on pods, causing them to curl, shrink and only partially fill. Direct feeding therefore leads to yield loss and reductions in crop quality. Bommarco (1991) calculated economic losses in pea through a number of seasons due to A. pisum; with observed yield losses of up to 230 kg/ha. Although direct feeding damage is significant, this aphid is primarily an economic pest on pea due to its ability to transmit viruses. Broad beans and a range of other bean crops can also suffer yield losses, through similar direct feeding impacts, from heavy infestations of A. pisum. On peas and beans, A. pisum secretes honeydew from its siphunculi, which can coat plants, reducing photosynthetic efficiency and resulting in the growth of unsightly sooty moulds.