Hawthorn-parsley aphid

Rhopalosiphum oxyacanthae

1. Identification

• Common name: Apple-grass aphid / Holly aphid / Hawthorn aphid (designations frequently used in technical literature).
• Scientific name: Rhopalosiphum oxyacanthae Schrank
• Order: Hemiptera
• Family: Aphididae

2. Pest description

• Apterous adults: Oval body, yellowish-green to greyish-green; relatively short and dark siphunculi; pale cauda.
• Alate adults: Dark head and thorax; transparent wings; yellowish-green abdomen.
• Nymphs: Similar to apterous adults, but smaller and with a paler colouration.

3. Main hosts

• Primary hosts: Crataegus spp. (hawthorn) and Sorbus spp.
• Secondary hosts: various grasses, including wild and cultivated species.
• It may occur in orchards near areas with primary hosts.

4. Symptoms and damage

• Rolling and deformation of young leaves on the primary hosts.
• Formation of dense colonies on the underside of the leaves.
• Excretion of honeydew, favouring sooty mould.
• On grasses, it may reduce vigour and affect growth, especially in young plants.
• Potential vector of viruses associated with cereals.

5. Biological cycle

• Holocyclic and dioecious species, alternating between woody hosts (primary) and grasses (secondary).
• It overwinters as an egg on the primary hosts.
• The first generations develop in spring, later migrating to grasses.
• In autumn, it returns to the primary hosts to lay the winter eggs.

6. Monitoring

• Observation of rolled young leaves on the primary hosts in spring.
• Counting of colonies on grasses during the summer.
• Assessment of the presence of honeydew and natural enemies.
• Regular monitoring in areas with a high presence of Crataegus spp.

7. Management measures

• Cultural: Removal of heavily infested shoots on the primary hosts; management of wild vegetation, especially grasses; avoid excess nitrogen.
• Biological: Conservation of beneficials such as Coccinellidae, Syrphidae, Chrysopidae and Aphidiinae parasitoids.
• Integrated protection: Intervention only when necessary; preference for selective products compatible with beneficials.

Bibliographic references

• Blackman, R. L., & Eastop, V. F. (2006). Aphids on the World’s Herbaceous Plants and Shrubs. Wiley.
• Blackman, R. L., & Eastop, V. F. (2000). Aphids on the World’s Crops: An Identification and Information Guide. 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.