Beet stem weevil

Systematic position: The beet stem weevil (Cleonis stratus) belongs to the order Coleoptera and the family Curculionidae. This pest is a specialized herbivore characterized by a distinctive elongated snout and a greyish-brown body covered in scales, which allows it to blend perfectly with its host plants and soil surfaces.

Host crops: The primary target of this pest is sugar beet. It also infests fodder beet and table beet. In addition to cultivated crops, several wild species of the Amaranthaceae family can host the beetle population, acting as reservoirs in the field environment during non-crop seasons.

Biology and life cycle: Adult weevils overwinter in the soil or under dense plant debris at depths up to 10 cm. When soil temperatures rise in the spring, adults emerge to feed on plant tissues. Females lay eggs in the leaf stalks or the crown of the root crop, where the larvae hatch and begin tunneling into the plant structure.

Nature of damage: Adults feed on the edges of leaves, causing minor damage; however, the larvae are significantly more destructive. By boring into the petioles and the root crown, larvae disrupt nutrient transport and structural integrity. This leads to stunted growth, wilting, and a substantial decrease in yield and sugar content, making the crop vulnerable to secondary infections.

Control measures: Integrated pest management (IPM) is crucial. Key agronomic practices include crop rotation to distance fields from previous seasons' sites and deep autumn plowing to disturb overwintering sites. Monitoring the threshold of the pest population is essential, and if necessary, authorized systemic or contact insecticides should be applied during the early growth stages to minimize damage.