Hazel aphid

The hazel aphid (Myzocallis coryli) is a specific insect species classified within the order Hemiptera and the family Aphididae. It is a monophagous pest that thrives exclusively on species of the genus Corylus, posing a consistent challenge for hazelnut growers worldwide.

The primary hosts of this aphid are cultivated hazelnuts and wild hazel species. Large colonies typically establish themselves on the underside of leaves, where they feed on phloem sap, impacting the overall vitality and nutrient balance of the host plant.

The life cycle begins with overwintering eggs deposited in bark crevices during the autumn. Once temperatures rise in spring, nymphs emerge to begin the cycle of growth. The species produces multiple generations throughout the season, characterized by both wingless and winged forms that facilitate rapid colonization of orchard sections.

Feeding damage results in leaf curling, yellowing, and necrotic spots. Furthermore, the excretion of honeydew promotes the growth of sooty mold, which blocks sunlight from leaf surfaces and reduces the plant's photosynthetic capacity, ultimately leading to smaller nut yields and lower kernel quality.

Integrated Pest Management (IPM) is essential for maintaining healthy orchards. Growers should focus on the following strategies:

• Monitoring aphid populations regularly to determine if the economic threshold has been reached.
• Applying dormant oil treatments in early spring to eliminate overwintering eggs.
• Encouraging biological control agents like ladybird beetles, lacewings, and parasitic wasps.
• Utilizing selective insecticides that preserve beneficial insect populations during the active season.