Banana Weevil (Cosmopolites sordidus)
The banana weevil is the most destructive insect pest of banana plants worldwide. The adult is a dark brown to black weevil about half an inch long that is active at night. Damage is caused by the larvae, which tunnel into the rhizome (corm) and pseudostem base, weakening the plant and creating entry points for disease.
Symptoms
- Tunnels and galleries visible when the pseudostem base or rhizome is cut open
- Yellowing, wilting, or toppling of the pseudostem
- Slowed growth
- Reduced or failed fruiting (Not Fruiting)
- Jelly-like sap oozing from the pseudostem base
Prevention
- Use clean planting material — inspect rhizomes for tunnels before planting. Tissue culture plants are guaranteed pest-free.
- Remove and destroy old pseudostem stumps after harvest — they are breeding sites
- Keep the area around plants clean of plant debris
- Trap adults using pseudostem sections laid cut-side down on the soil — check and destroy trapped weevils daily
Treatment
Infested plants can be treated by paring away damaged rhizome tissue and applying insecticide to the corm. Beneficial nematodes (Steinernema and Heterorhabditis species) are an effective biological control when applied to the soil around the base of the plant. In severe infestations, systemic insecticides may be necessary.