Willow aphid

Systematic position: Macrosiphum laevigatae belongs to the order Hemiptera and the family Aphididae. It is a specialized aphid species that primarily targets members of the Salix genus. Its classification highlights its evolutionary adaptation to willow species, making it a recurring issue in both nursery management and landscape forestry.

Host plants: The primary hosts are various species of willow (Salix). The aphid is particularly significant for ornamental willow gardens, basketry willow plantations, and ecosystem restoration projects. It thrives in humid conditions where willow stands are dense and sheltered, allowing the colony to establish itself quickly.

Biology and life cycle: The life cycle of Macrosiphum laevigatae is complex, involving both sexual and asexual reproduction phases. Eggs overwinter on the bark of twigs. As temperatures rise in spring, fundatrices hatch and begin the cycle of rapid parthenogenetic reproduction, resulting in multiple generations throughout the growing season.

Damage and harmfulness: These aphids cluster on young, succulent shoots and the underside of leaves to extract phloem sap. This feeding process causes severe leaf curling, stunted shoot growth, and loss of aesthetic value for decorative willows. Furthermore, the honeydew secreted by the aphids serves as a substrate for sooty mold growth, further debilitating the host plant.

Protection measures: Effective management relies on early detection and integrated pest management (IPM) strategies:

• Regular monitoring of terminal shoots during the spring growth flush.
• Encouraging natural predators such as lady beetles, lacewings, and hoverfly larvae.
• Application of systemic insecticides during peak infestation periods if necessary.
• Pruning and destroying heavily infested branches to reduce the initial population size.