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Direct damage due to sap removal

This is related simply to the extraction of the plant’s nutrients. The aphids, being piercing and sucking insects, feed themselves by taking up and absorbing their host’s sap. This weakens the plant, which grows poorly, wilts and can dry out completely. The damage starts to show, depending on the stage of the plant, by diminished growth, poor fructification (aborted fruit) or a decrease in the number of seeds (yield loss). The damage will depend on the duration of the aphids’ presence and their numbers on the plant for each stage of development, also on the plant’s level of sensitivity to these insects.

Direct damage due to saliva secretions

Aphid saliva exerts an irritant, toxic action: the plant reacts to the piercing for food and to the presence of saliva, often in a specific way. It may be leaf deformation, whereby leaves fold up and wrinkle, roll up, shrivel, show an embossed effect, crinkle, thicken, blister, swell, become corrugated, with or without colour change. Sometimes shoots become stunted and shrivel, twist, the internodes are short, flowers abort and dry up, the leaves fall, fruit look dented, hardly grow in size and lack flavour. Moreover cankers appear on branches or roots, galls form on leaves or stems.

Aphis fabae damage on artichoke	Aphis gossypii damage on courgette	Brevicoryne brassicae damage on rape	Myzus cerasi damage on cherry

Aulacorthum solani damage on Calceolara	Brachycaudus helichrysi damage on sunflower	Dysaphis plantaginea damage on apple	Pemphigus spyrothecae gall