Clay-colored weevil

Systematic position. The clay-colored weevil (Otiorhynchus dubius) belongs to the order Coleoptera and the family Curculionidae. It is a significant agricultural and horticultural pest known for its ability to damage a wide variety of plants, particularly in temperate climates across Europe and beyond.

Host plants. This species is highly polyphagous, meaning it feeds on a broad range of host plants. It commonly impacts berry crops like strawberries and raspberries, as well as various ornamental shrubs, perennial flowers, and nursery-grown woody plants, causing significant economic losses in commercial nurseries and private gardens.

Biology and life cycle. The life cycle involves egg, larval, pupal, and adult stages. Adult weevils are flightless and nocturnal, hiding in the soil or under debris during the day. Eggs are laid in the soil near the host plant, and the resulting larvae live underground, feeding on the root system throughout their development, which can span several months.

Damage and harm. The primary symptoms of adult activity are the notched or scalloped edges of leaves, caused by feeding. The larval stage is far more destructive, as they consume root hairs and main roots. This root damage inhibits the plant's ability to absorb water and nutrients, leading to stunted growth, yellowing foliage, and eventually the death of the plant.

Control measures. Integrated pest management (IPM) is essential for effective control. Cultural practices such as crop rotation, soil cultivation to expose larvae, and manual removal of adults at night are useful. Chemical control involves the application of appropriate insecticides during the adult feeding phase or the use of biological control agents, specifically entomopathogenic nematodes applied to the soil to target the larvae.