Sweet potato hornworm

Systematic position: Herse cingulata (commonly known as the sweet potato hornworm or Agrius cingulata) belongs to the order Lepidoptera and the family Sphingidae. These moths are recognized by their streamlined bodies and long, narrow wings, often displaying distinctive pinkish or greyish patterns.

Affected crops: This pest primarily targets plants within the Convolvulaceae family. While the sweet potato (Ipomoea batatas) is its most significant agricultural host, the insect is also frequently found on various morning glory species and related ornamental vines.

Biology and life cycle: The life cycle progresses through egg, larval (caterpillar), pupal, and adult stages. The female moth lays eggs individually on the underside of leaves. Upon hatching, the larvae go through several developmental instars. Once mature, the caterpillars descend into the soil to pupate, which is a critical phase for overwintering or entering a quiescent state.

Damage and severity: Hornworms are notorious for their voracious appetite. Caterpillars consume large quantities of foliage in a very short time. Severe infestations can result in total defoliation of the plants, which disrupts energy storage in the tubers, leading to significant yield loss and reduced root size.

Control measures: Integrated pest management is recommended for effective suppression.

• Regular field scouting to detect the presence of egg clusters or early-instar larvae.
• Application of selective microbial insecticides, such as products containing Bacillus thuringiensis, which target larvae without harming beneficial insects.
• Sanitary practices, including the removal of wild host plants from field borders.
• Post-harvest soil tillage to disrupt and destroy pupae residing in the upper layers of the soil.