Alder flea beetle

The Alder flea beetle (Altica bimarginata) is a member of the family Chrysomelidae within the order Coleoptera. This species is a recognized pest that targets alder species, often causing significant aesthetic and physiological damage to forest and ornamental trees.

The host plants mainly include various species of the genus Alnus. When populations reach outbreak levels, the beetle can cause extensive defoliation, leading to stunted tree growth and increased susceptibility to secondary pests, pathogens, and drought stress.

The biology of Altica bimarginata involves a single generation per year. Adults overwinter in protected sites such as leaf litter or soil crevices. As temperatures rise in the spring, the beetles emerge to feed on developing foliage and subsequently lay eggs, beginning the reproductive phase.

The feeding damage is caused by both adults and larvae. Adults create small, shot-hole perforations in the leaf blades, whereas the larvae primarily skeletonize the leaves, feeding on the tissue between the veins. Severe infestations result in browning, drying, and premature leaf drop.

• Sanitation: Remove and dispose of infested leaf litter during autumn.
• Monitoring: Conduct regular checks during the spring leaf-flushing phase.
• Biological control: Encourage predatory insects and birds in the area.
• Chemical treatment: Apply selective insecticides only when the damage threshold is met.

Effective management of the Alder flea beetle relies on early detection and integrated pest management practices. By maintaining tree vigor and applying targeted controls when necessary, it is possible to mitigate the impact of this pest and protect the health of alder populations.