Root weevil

Root weevils of the genus Otiorhynchus (family Curculionidae) are among the most destructive pests affecting nursery stock, ornamental plants, and various berry crops globally. They are well-known for their nocturnal feeding habits and soil-dwelling larval stages.

These insects belong to the order Coleoptera. Their life cycle is complex, often spanning one or more years. Adults are flightless in many species, which leads to localized infestations that persist in the soil until successfully treated with specific control methods.

Damage is twofold: larvae feed on roots and root crowns, causing severe water stress, nutrient deficiency, and eventually plant death. Adult beetles feed on foliage, creating distinctive notched edges along the leaves, which significantly impacts the aesthetic value of ornamental plants.

The biological cycle involves eggs deposited in the soil near the host plant, followed by larval development underground. The pupal stage is also spent in the soil. Understanding the timing of adult emergence is critical for successful control programs to prevent egg-laying.

Integrated pest management (IPM) is essential for controlling root weevils. Key strategies include:

• Application of entomopathogenic nematodes (such as Heterorhabditis bacteriophora) in moist soil.
• Use of fungi like Beauveria bassiana.
• Night-time insecticide applications when adults are active on foliage.
• Frequent soil cultivation to expose larvae to natural predators.