Chestnut aphid

Systematic position: The chestnut aphid (Thelaxes castaneae) is a member of the order Hemiptera and the family Thelaxidae. This insect is a specialized feeder known for its specific host plant association, making it a distinct pest in both natural chestnut forests and cultivated chestnut plantations.

Host plants: The primary host for this species is the sweet chestnut (Castanea sativa). Its distribution is largely dictated by the presence of these trees, making it a notable concern for arborists and orchard managers in regions where chestnut production is significant.

Biology and lifecycle: The lifecycle of Thelaxes castaneae is adapted to the growth pattern of its host tree. The aphids typically aggregate on the undersides of leaves. Overwintering occurs in the egg stage, which is usually deposited in the crevices of the bark on young shoots, ensuring the survival of the population during the dormant period.

Damage and severity: The feeding activity of these aphids extracts essential plant sap, which leads to leaf curling, chlorosis, and reduced vigor of the tree. The production of honeydew often triggers the growth of sooty mold, which creates a dark coating on the leaves and interferes with photosynthesis, potentially impacting the overall yield of nut-bearing trees.

Control measures: Management strategies should focus on early detection and maintaining tree health. Key control methods include:

• Pruning and removal of heavily infested shoots during the dormant season.
• Encouraging natural predators such as lady beetles and lacewings.
• Applying systematic insecticides if the population levels threaten tree vitality.
• Monitoring the health of chestnut stands to prevent secondary infections.