Responses of summer cereal aphid populations to reduced rate aphicide applications in field plots of winter wheat

Abstract

Abstract 1 Recommended and reduced rate applications of pirimicarb and alpha‐cypermethrin were applied to winter wheat crops to control summer infestations of grain aphid (Sitobion avenae) and rose‐grain aphid (Metopolophium dirhodum).2 Aphid numbers were assessed weekly and the yield response to treatment application was compared with accumulated aphid days on the crop.3 Responses to aphicide treatment varied between sites according to variations in the subsequent development of aphid populations under varying weather conditions and differential pressures from aphid natural enemies.4 Alpha‐cypermethrin treatment reduced spider density at most sites, and also resulted in a resurgence of aphid populations at three sites.