Buckthorn-potato aphid

Aphis nasturtii 

1. Identification

• Common name: Buckthorn aphid
• Scientific name: Aphis nasturtii Kaltenbach
• Order: Hemiptera
• Family: Aphididae

2. Pest description

• Apterous adults: Small, oval body; dark green to brownish-green colouring; dark, relatively short siphunculi; pale cauda.
• Alate adults: Darkened head and thorax; transparent wings; body darker than the apterous forms; wing venation typical of the genus Aphis.
• Nymphs: Similar to apterous adults, but smaller and with more uniform colouring.

3. Main hosts

• Species of Crataegus (buckthorn).
• Also recorded on currant, watercress and other herbaceous plants.
• May occur in horticultural crops close to primary hosts.

4. Symptoms and damage

• Curling and deformation of young leaves.
• Reduced vegetative vigour and stunted growth.
• Excretion of honeydew, favouring the development of sooty mould.
• Formation of dense colonies on shoots and tender leaves.
• Potential for transmission of phytopathogenic viruses on secondary hosts.

5. Biological cycle

• Species with several generations per year.
• Parthenogenetic reproduction during much of the year.
• Frequently heteroecious cycle, alternating between woody and herbaceous hosts, depending on the region.
• Populations increase in mild climates and low presence of natural beneficials.

6. Monitoring

• Direct observation of the underside of young leaves and shoots.
• Assessment of the presence of colonies, honeydew and sooty mould.
• Counting of individuals per leaf or per shoot to support decision-making in integrated protection.

7. Management measures

• Cultural: Removal of heavily infested shoots; elimination of alternative hosts; management of wild vegetation.
• Biological: Conservation of beneficials such as Coccinellidae, Syrphidae and parasitoids Aphidiinae.
• Integrated protection: Intervention only when population levels justify it; preference for selective methods compatible with beneficials.

Bibliographic references

• Blackman, R. L., & Eastop, V. F. (2000). Aphids on the World’s Crops: An Identification and Information Guide. Wiley.
• Blackman, R. L., & Eastop, V. F. (2006). Aphids on the World’s Herbaceous Plants and Shrubs. Wiley.
• van Emden, H. F., & Harrington, R. (2017). Aphids as Crop Pests (2nd ed.). CABI.
• Dixon, A. F. G. (1998). Aphid Ecology: An Optimization Approach. Chapman & Hall.