Sudan bollworm

The Sudan bollworm, belonging to the genus Diparopsis and the family Noctuidae (order Lepidoptera), is a significant agricultural pest that primarily targets cotton crops. Known for its host-specific behavior, this insect can cause severe economic damage to cotton production in tropical and subtropical regions, particularly in Africa.

The primary host for Diparopsis is cotton (Gossypium spp.). Larvae are highly specialized feeders that attack the generative organs of the plant. They demonstrate a strong preference for flower buds and developing cotton bolls, which are essential for yield formation. Without proper control, the damage can lead to substantial reductions in fiber quality and total output.

The life cycle follows a complete metamorphosis: egg, larva, pupa, and adult. Eggs are typically laid individually on the leaves or buds. Upon hatching, the larvae immediately seek out the reproductive parts to bore inside. A critical feature of its biology is the ability of pupae to enter a diapause state in the soil, which allows the species to survive between cropping seasons and ensures population continuity.

Damage assessment reveals that the presence of Diparopsis leads to "flared" squares (damaged buds) and bored bolls. These damaged bolls are prone to secondary infections from fungi and bacteria, which cause them to rot prematurely. The larvae's habit of feeding inside the boll protects them from many external threats, making control a challenging task.

Integrated Pest Management (IPM) is essential for controlling this pest and should include:

• Crop rotation to reduce larval survival in the soil.
• Deep plowing at the end of the season to expose pupae to predators and desiccation.
• Manual removal and destruction of infested buds and bolls during the season.
• Targeted application of insecticides during the early larval stage, before they bore into the bolls.