1. Rhizome weevil: Cosmopolites sordidus (Curculionidae: Coleoptera)

Distribution and status: India, South East Asia, Australia, Hawaii Islands, Tropical South Africa and Tropical America. Major pest.

Host range: Banana, cocoa

Damage symptoms

Grubs bore into the rhizome causing death of unopened pipe, withering of outer leaves and finally death of the plant.

Bionomics

Eggs laid in small burrows scooped out by the beetle on the root stock or within leaf sheaths, egg period 5-8 days. Grub is apodous and yellowish with reddish head becomes full-grown in 25 days. Grub pupates within chamber made near the outer surface of the rhizome, pupal period 5-6 days. Adult tunnels within stem, feeding on its internal tissues and lives for one year.

Management

• Use healthy and pest free suckers
• Trap the adult weevils by placing chopped pseudostem in the cropped area
• Uproot and destroy infested rhizomes
• Select infestation - free suckers
• Under take soil incorporation of lindane 1.3 D 20 g/plant or carbaryl 5D 10-20 g/plant or carbofuran 3G 20 g/plant or phorate 10 G 10 g/plant around pseudostem.
• Adopt paring and pralinage of banana suckers before planting.