Learn about the pests that damage banana and its control.
1. Banana Scale Moth, Nacoleia Octasema (Meyrick) (Lepidoptera: Pyralidae):
The caterpillars of the banana scale moth feed on the inflorescence of banana. They can also develop on Manila hemp, maize and some wild plants. This pest occurs in Indonesia, eastern Australia, New Guinea, Solomon Islands, Fiji, Tonga, Samoa and Queensland. The moth has a wing span of 22 mm and its colour varies from light brown to dark brown.
Life-Cycle:
The activity of the moths coincides with the growth of banana plants. The female moths lay pale greenish-white eggs on or near the flag leaf of banana plant just before the bunch emerges. The eggs hatch in about 4 days and the small transparent yellow caterpillars crawl under the closed bracts of the young banana bunch and begin feeding there. After completing this development the larvae may pupate right on the plant or more often in the debris near the base.
The caterpillars are attacked by Sisyropa panci (Tachinidae), Macrocentrus sp. (Braconidae) and Argyrophylae sp. (Tachinidae) which are the larval parasites of this pest.
Damage:
The gregarious caterpillars feed on the young female flowers and leave scale-like scars on the young fruits. They feed so voraciously that the inflorescence is soiled with frass and refuse of the larvae, and gives an ugly appearance.
Control:
Spray 2.5 kg of carbaryl 50WP in 1250 litres of water per ha directing the spray towards the bracts of the inflorescence.
2. Banana Stem Borer, Odoiporus Longicollis (Olivier) (Coleoptera: Curculionidae):
It is a serious pest of banana in North-east India. The adult is a robust reddish brown weevil about 1.5-2.0 cm long. The grub is apodous, yellowish with reddish head.
Life-Cycle:
The eggs are laid in small burrow in the rhizome or within leaf sheaths just above the ground. Eggs hatch in 3-5 days in summer and 5-8 days in winter. The larva bores into pseudostem making tunnels within and cutting holes on its outer surface. The larval duration is 26 days in summer and 68 days in winter with five larval instars. It pupates in tunnel towards the periphery. The pupal period lasts 20-24 days in summer and 37-44 days in winter. The adult lives for a period of upto two years.
Damage:
Both the grubs and adults cause the damage. Grubs bore into the rhizome and make tunnels within it. Adults also tunnel within the stem, feeding on its internal tissues as a result of which the internal shoot is killed. Infested plants show premature withering, leaves become scarce, fruits become undersized and their suckers are killed outright.
Control:
(i) Uproot and burn the infested plants.
(ii) Suckers should be dipped in a solution of lindane (0.2%) to kill eggs inside.
(iii) Spray 2.5 kg of carbaryl 50WP in 1250 litres of water/ha.
3. Banana Aphid, Pentalonia Nigronervosa Coquerel (Hemiptera: Aphididae):
It is not a serious pest of banana, but it is notorious as the vector of the virus causing the bunchy top disease in banana. The aphid is brownish in colour and has black-veined wings. Apart from banana, it also attacks cardamom, large cardamom and Colocasia antiquorum.
Life-Cycle:
The aphid lives in colonies within the leaf-axils, or tender leaves and at base of the culm at the ground level. Young ones are given birth by alate and apterous females by parthenogenetic development. An aphid is capable of producing 30-50 nymphs in its life time of 27-37 days. The nymph undergoes four instars of 2-3 days duration each. Total life-cycle is completed in 8-9 days. From 30 to 40 generations are completed during a year under South Indian conditions.
Damage:
Both nymphs and adults suck the sap from the tender leaves. The pest is very important because it transmits the bunchy top virus.
Control:
Spray 1.70 litres of dimethoate 30EC or 1.25 litres of oxydemeton methyl 25EC in 1250 litres of water/ha.
4. Banana Weevil, Cosmopolites Sordidus (Germar) (Coleoptera: Curculionidae):
The larvae of the banana weevil, also known as the banana beetle and banana borer, bore into the corm of the banana plant. This species although native to South-east Asia, has attained wide distribution on cultivated bananas of the world. Its present distribution, in addition to India and South-east Asia, covers parts of Australia, the Hawaii Islands, tropical and South Africa and tropical America.
Life-Cycle:
The female weevil bites a small hole in the corm, lays a single egg and continues this activity on other plants throughout the year. A female can lay 10-50 eggs during its life of a few months. The larvae emerge from the eggs in about a week and bore into the corm, where they feed, making a tunnel.
When full-grown in 2-6 weeks, the larvae pupate in the same tunnel. The pupal stage lasts about a week. The adults, on emergence, remain in the soil for some time, feeding on the underground parts of the plants. Later on, they visit the growing point for oviposition.
Damage:
This insect attacks only members of the genus Musa. The damage done by the weevil is through the destruction of the corm tissue. The seedlings are killed as a result of the borer attack when the larvae approach the growing-point. The tunnelled corms sometimes break out, since the weevils do not attack the roots, they do not cause toppling over.
Control:
(i) Out of the various methods of control, cultural operations are the most important. They consist in destroying the sheltering and feeding places of the adult weevils. The pseudostems, from which the bunches have been cut, are chopped up and scattered in the plantation so that they rot quickly. Also, the pesudostems should be cut close to the ground and the infested suckers should not be used for planting,
(ii) Suckers should be dipped in 0.1 per cent quinalphos emulsion before planting. In case of attack, spray 315 ml of phosphamidon 100 or 625 ml of dimethoate 30EC in 625 litres of water per ha, around the base of the plants or clumps.