Sweet potato stem borer

The sweet potato stem borer (lat. Cylas femoralis) is a significant agricultural pest that specifically targets sweet potato crops. Classified within the order Coleoptera and the family Brentidae, this beetle is known for its destructive impact on both commercial and subsistence farming of Ipomoea batatas.

The primary host for this pest is the sweet potato. The insect infests the stems, crowns, and tubers of the plant, causing severe physiological stress and destruction of the edible storage roots, which can lead to catastrophic losses if left unmanaged.

The biological cycle of Cylas femoralis is characterized by internal feeding. Females deposit eggs into small cavities they create in the stems or tubers. The emerging larvae are legless and burrow throughout the plant tissues, feeding exclusively internally until they pupate within the excavated tunnels.

The resulting damage is characterized by intricate tunnels filled with frass, which often leads to secondary infections by bacteria and fungi. This makes the tubers unfit for human consumption, as the feeding causes bitterness and structural decay, significantly lowering the quality and marketability of the crop.

Effective management requires a combination of cultural and chemical strategies to reduce population pressure. Recommended practices include:

• Utilizing healthy, pest-free planting slips for new crops.
• Implementing strict crop rotation to move away from infested soil patches.
• Practicing thorough sanitation by removing and destroying crop residues immediately after harvest.
• Applying registered insecticides during the vegetative growth phase to prevent egg-laying.