Cotton stem weevil

The Pempherulus affinis is a destructive beetle species classified under the order Coleoptera and the family Curculionidae. It is widely recognized as a serious pest of cotton crops, causing significant economic losses in various tropical and subtropical agricultural areas where this fiber plant is cultivated.

This pest exclusively targets members of the Malvaceae family, with cotton (Gossypium) being the primary host. The insect thrives in warm climates, often reaching high population densities in monoculture systems, where it continuously impacts the developmental stages of the host plants.

The biology of the pest is defined by its endophytophagous nature. The female beetle lays eggs into the plant stem, and upon hatching, the larvae burrow into the tissue to feed. This internal lifestyle makes them difficult to target with conventional contact-based pesticides during the peak of their larval development phase.

Visible damage is characterized by the formation of galls or swelling on the main stem and branches. This mechanical injury interferes with the plant’s ability to transport water and nutrients, resulting in stunted growth, yellowing, poor fiber quality, and in severe cases, the lodging or death of the entire plant.

Management strategies require a multi-faceted approach to reduce pest pressure.

• Deep plowing of fields after harvest to destroy dormant life stages.
• Immediate removal and destruction of infested plants to prevent population buildup.
• Application of systemic insecticides specifically timed with adult egg-laying activity.
• Utilization of crop rotation to break the pest's reproductive cycle.