Sternechus pinguis

Sternechus pinguis is a significant insect species belonging to the family Curculionidae (true weevils). This pest is predominantly recognized in South American agricultural landscapes, where it acts as a primary threat to soybean production. It is characterized by its specific feeding behavior and destructive impact on legume crops during their vegetative stages.

The primary host for this weevil is soybean. Adults primarily feed on the foliage and terminal buds, causing minor damage, but the larvae are the most destructive stage. They bore into the stems of soybean plants, creating internal galleries that disrupt the vascular system and compromise the structural integrity of the plant, often leading to reduced vigor and yield loss.

The biological cycle of this pest typically consists of the egg, larval, pupal, and adult stages. Females lay eggs directly into the soybean stems or near the crown. Once hatched, the larvae tunnel into the plant tissue, remaining protected from external environmental factors. The pupation phase usually occurs within the stem or in the soil, depending on the specific environmental conditions and the crop's developmental stage.

Damage symptoms include stem swelling (galls), necrotic lesions on the stem surface, terminal wilting, and in severe cases, the snapping of stems under wind pressure. By feeding internally, the larvae facilitate the entry of pathogens and weaken the plant's ability to transport nutrients and water, which ultimately results in diminished pod formation and lower grain weight.

Effective management strategies require an integrated approach (IPM). Key preventive measures include crop rotation to break the pest cycle, thorough destruction of crop residues post-harvest, and deep tillage to expose pupae to predators and environmental stress. When economic thresholds are surpassed, the application of systemic insecticides is necessary to target larvae within the stem, complemented by foliar treatments aimed at adult weevils before oviposition occurs.

• Regular field scouting during the early vegetative phase.
• Elimination of alternative weed hosts in and around fields.
• Application of seed treatments with systemic action.
• Strategic timing of insecticide applications based on beetle activity.