Damage of the green pepper plant, capsicum annuum (L.), caused by the green peach aphid, myzus persicae (sulzer) (homoptera:aphididae)

Abstract

Damage of the green pepper plant, Capsicum annuum (L.) (cv. Nockwang) caused by the green peach aphid (GPA), Myzus persicae (Sulzer) was assessed to develop the economic injury level of the GPA for pepper management. Plant damage was assessed with different initial GPA densities and different feeding duration periods at different plant growth stages (15 and 30 days after transplanting [DAT]). Plant damage increased as initial aphid density and feeding duration increased. At initial density of 5 GPA at 15 DAT plant stage, leaf area, plant height and node number were reduced by approximately 75, 25 and 52 %, respectively by 30-day-feeding: 35,000-45,000 cumulative aphid days [CAD] resulting in 100 % flower abscission rate. Plant damage by 30-day-feeding of the GPA population was higher at early plant growth satge (15 DAT) than late plant growth stage (30 DAT). The fresh weights of leaf, stem, root and fruit decreased by 7, 11, 21 and 84%, respectively at 15 DAT, and by 49, 22, 28 and 47%, respectively at 30 DAT. Plant damage by the GPA and plant recovery after removal of the GPA populations occurred faster at early season than at late season. Fruit fresh weights also decreased linearly as cumulative aphid-days increased. In conclusion, damage of the green pepper plants by 10,000 CAD was not significant, and damage by 35,000-45,000 CAD considerably increased, so I recommend appropriate control densities as 5,000-15,000 CAD corresponding to 30-70 aphids per cluster per plant.