Andean potato weevil

The Andean potato weevil (Premnotrypes pusillus) is a significant insect pest belonging to the order Coleoptera and the family Curculionidae. It is recognized as one of the most destructive pests affecting potato production in the Andean regions, causing substantial economic losses annually.

The primary host plant is the potato, although other Solanaceae species can also serve as hosts. Adult weevils feed on the foliage by notching the leaves, but the major damage is caused by the larvae, which bore into the potato tubers. This life stage is particularly difficult to control due to its cryptic behavior inside the tuber.

The life cycle involves the female laying eggs in the soil or at the base of the plant stem. Upon hatching, the larvae move into the soil to find tubers and burrow into them. Within the tuber, they create galleries while feeding, which compromises the integrity and marketability of the harvest.

The damage is often characterized by hidden galleries filled with frass, which lead to rapid decay of the tubers once secondary fungi and bacteria invade. Because the damage occurs internally, farmers often do not realize the extent of the infestation until the tubers are sliced or stored, where further rotting may occur.

Effective management strategies for this pest include:

• crop rotation with non-host crops to interrupt the life cycle;
• utilizing certified pest-free seed potatoes;
• application of soil-incorporated insecticides at planting or earthing-up;
• deep tillage to expose larvae and pupae to predators and environmental stress;
• monitoring adult activity using manual collection or traps to time control interventions.