The rosy apple aphid, Dysaphis plantaginea, is a serious apple pest. It is widespread in Europe and also occurs in Africa, North and South America, and Asia and can cause severe damage to both shoots and fruits.
Life cycle and appearance of Rosy apple aphid
Aphids have a complex life cycle, with both winged and wingless forms of adults, and a great variety in colour. They moult four times before reaching adulthood. With each moult they shed white skin, betraying their presence in the crop.
Adult viviparous (wingless) females of the rosy apple aphid are 2.1-2.6 mm long and pink to dark bluish grey, with a powdering of white wax. The siphunculi are black and tapered, the cauda is dark, short and triangular.
Dysaphis plantaginea lays eggs in autumn in bark crevices on spurs and smaller branches, and on the base of buds of apple trees. The eggs hatch in spring and at first the aphids attack buds, spur leaves and rosette leaves. Later the infestation spreads to young shoots. In spring and summer, reproduction takes place by parthenogenesis, with unfertilized viviparous females continuing to produce new generations of females. By late May or June (in the northern hemisphere) multiple large colonies may be present on the trees. Winged aphids are produced in June or July. They move to plantain trees (Plantago spp.), the summer host. However, breeding on apple can continue until August. In early autumn, winged rosy apple aphids move back to apple for egg-laying.
Infested apple leaves are severely curled downwards and disfigured. They sometimes turn yellowish or brown. Attacked shoots are stunted and twisted. Heavy attack can lead to premature leaf fall and death of shoots.
Fruits from infested trusses are small and malformed and ripen prematurely. Feeding of aphids directly on fruits causes reddish blotches on the skin.