The buckthorn-potato aphid, Aphis nasturtii, has a nearly cosmopolitan distribution and is a major pest of potatoes, where it also transmits viruses. It also attacks a large number of other crops, for instance sweet pepper, tomato, aubergine, strawberries and gerbera and worldwide distribution.
Life cycle and appearance of Buckthorn-potato aphid
Aphids have a complex life cycle, with both winged and wingless forms of adults and a great variety in colour. In greenhouses, reproduction takes place by parthenogenesis, with unfertilized viviparous females continuing to produce new generations of females. Aphids moult four times before reaching adulthood. With each moult they shed white skin, betraying their presence in the crop.
Wingless females of the buckthorn-potato aphid are 1.1-2.4 mm long and bright pale green to yellowish green. The antenna are relatively short and barely exceed half the body length.
The aphids overwinter as eggs on buckthorn. After emerging in spring, the aphids mainly feed on the underside of leaves of their summer hosts and start to reproduce parthenogenetically. Both wingless and winged forms are produced parthenogenetically. They are usually found in the lower parts of the plants and are not very mobile. In autumn, winged males and females are produced, which return to the primary host buckthorn where they lay eggs for overwintering.
Direct damage, caused by sucking of sap is rarely seen. Sometimes, large populations build up on potatoes or other hosts, which can cause growth retardation. Buckthorn-potato aphid does not cause plant deformation. The major problem in potatoes is the transmission of viruses.