The Banana scab moth, belongs to the family of Crambidae and is considered a serious pest in banana plantations. Its damage to the fruit can result in downgrading and/or rejection of the fruit thus great economic losses.
The adult moth is small, 25-30mm wingspan, tan to light brown in colour with small black spots on the wings.
Eggs are flattened and laid in clusters ranging from a few to 30 eggs. They resemble shiny overlapping fish scales.
Larvae are yellow to orange in colour and grow to about 25 mm before pupating.
Eggs are laid on or near to an emerging bunch and hatch after about 4days and the young larvae move under the tightly closed bracts where they feed on the young fruit. Larval development consists of five instars and is completed in an average of 14 days.
As the bracts and hands progressively lift from the bunch stalk during bunch development, larvae move progressively to the next closed distal hand. Development is usually completed under the bracts which remain attached to the distal male flower bud.
The larvae spin a thin silken cocoon, adding some rubbish, which helps to hide them. Inside the cocoons, the caterpillars turn into brown pupae. The cocoons are either on the banana plant or nearby in the leaf litter.
The pupal period lasts 8-10 days and is completed on the bunch, in trash or in old leaf axils on the pseudostem.
The life cycle is completed in 28 days under relatively hot wet conditions.
Adults are short-lived, they live for 4-5 days and have crepuscular habits.
Mating and egg laying takes place in the early evening.
Adult moths hide in trash and under old leaf axils during the day.
Upon emergence the larvae make their way to the bunch and start feeding on inflorescences and the surface of the developing fruit, causing unsightly cosmetic damage and loss of marketability.
Sometimes, they eat through the skin and feed on the banana pulp.
The larvae prefer to feed in sheltered positions, and concentrate their attack on fruit still protected by unsheathing bracts. As bracts begin to lift and fall, the larvae migrate down the bunch to the next bract-encased hand.
If larval development has not been completed by the fall of the last bract, larvae may either remain in the bell at the base of the bunch feeding on male inflorescences, or migrate back up the bunch feeding on the maturing fruit.
Black scabs and/or caterpillar droppings are seen on the skin.
Significant losses occur in severe cases of attack by the pest.
This pest is most active during the hot wet weather.
Several techniques can be used to control/and manage banana scab moth.
They include the following;
This involves the use of chemicals. The following insecticides are recommended for use against this insect pest’
- KINGCODE ELITE 50EC 10ml/20l
- PENTAGON 50EC 10ml/20l
- LEXUS 247SC 8ml/20l
- LEGACY 50EC 15ml/20l
- SINOPHATE 750SP 20g/20l
- PRESENTO 200SP 5g/20l
- ESCORT 19EC 10ml/20l
- PROFILE 440EC 30ml/20l
BACIGUARD 16WDG 15g/20l is a biological insecticide which acts by multiplying bacteria strain of Bacillus thuringiensis (Bt) on the moth’s body thus eliminating it.
This majorly entails the farm practices and include the following;
- Crop rotations with non-host plants
- Maintenance of field hygiene/sanitation
- Proper weed control
- Planting tolerant varieties
- Use of natural enemies like wasps
- Whenever spraying any insecticide, it is advisable to mix it with INTEGRA 3ml/20l. This is a sticker, spreader and penetrant which improves the efficacy of the product.
- Timely application of the insecticide is very critical for effective control of the moth.
- To avoid resistance build-up by the pest, several insecticides should be alternated throughout the crop season.