Basic biology of the buckthorn–potato aphid

Buckthorn–potato aphid is a relatively minor pest of potato because populations rarely grow large enough to cause economic damage through direct feeding. However, very heavy infestations can seriously damage the haulm and reduce yields, and the aphid can transmit non–persistent viruses. 

• Warm conditions in late spring/early summer can promote large populations
• Most direct damage is caused during tuber bulking in late July and August

Scientific name: Aphis nasturtii 

Wingless adults are relatively small (1–2 mm) and bright yellow–green. 

Oct–May: Eggs overwinter on buckthorn. 

May–Oct: Winged adults move into crops in May/June and reproduce throughout the summer. 

Oct–Nov: Winged adults migrate to buckthorn to lay eggs. 

Potato virus Y (PVY) infections result in leaf drop streak, whereby the lower leaves develop black streaks on their underside veins and eventually collapse – hanging off the stem by a thread. Younger leaves may develop necrotic spotting.  

Potato virus A (PVA) infections usually cause mild mosaic symptoms. 

Non-chemical control 

Natural enemies include parasitic wasps, ladybirds, hoverflies, lacewings, and insect-pathogenic fungi, which may help control aphid numbers. However, they may not be effective in preventing virus transmission, as this can occur even at low aphid densities. 

The use of seed potatoes certified by the British Seed Potato Classification Scheme reduces the virus risk and its subsequent spread by aphids. Potato varieties differ in their susceptibility to aphid infestation and virus infection. If the crop is grown in a high-risk area, seek expert advice about which crop variety to choose.  

Monitoring 

Buckthorn–potato aphids are rarely caught in suction traps, so winged migration data is not available.  

Thresholds 

None established. Control measures are usually unwarranted. 

Insecticide resistance 

None known.