Cotton Aphid

Aphis gossypii 

1. Identification

• Common name: Cotton aphid
• Scientific name: Aphis gossypii Glover
• Order: Hemiptera
• Family: Aphididae

2. Pest description

• Apterous adults: Small, oval body; colouring varying between light green, yellowish-green, brown or almost black; dark, relatively short siphunculi; pale cauda.
• Alate adults: Darkened head and thorax; transparent wings; body generally 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

• Horticultural crops: Cucurbits (melon, watermelon, cucumber, squash), solanaceous and other horticultural crops.
• Industrial crops: Cotton.
• Ornamental and wild plants: Various herbaceous and shrubby species.

4. Symptoms and damage

• Curling and deformation of young leaves.
• Reduced vigour and stunted growth.
• Abundant excretion of honeydew, favouring the development of sooty mould.
• Transmission of various phytopathogenic viruses, especially in cucurbits.
• Formation of dense colonies on leaves, shoots and flowers.

5. Biological cycle

• Highly polyphagous species, with multiple generations per year.
• Predominantly parthenogenetic reproduction in temperate regions.
• Rapid development, favoured by mild temperatures and low pressure from beneficials.
• High dispersal capacity due to the frequent production of alate forms.

6. Monitoring

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

7. Management measures

• Cultural: Removal of heavily infested plants; elimination of wild hosts; appropriate management of planting density.
• Biological: Conservation of beneficials such as Coccinellidae, Chrysopidae, 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.