The red palm weevil is one of the most destructive pests of coconut, oil palms and ornamental palms. Identification of the pest eggs are oval and creamy white in colour and are laid in scooped out small cavities, wounds and other cut injuries in the trunk.
The grub is light yellowish without legs. It is stout and fleshy with a conical body bulged in the middle and tapering towards the end. The full grown larva pupates inside the stem and the cocoon is made out of fibrous strands. The adult weevil is reddish brown and has six dark spots on the thorax. The male has a conspicuous long snout with a tuft of hair.
Symptoms of damage
1. Holes can be seen on the stem with chewed up fibres protruding outwards.
2. Reddish brown liquid can be seen oozing out from the hole.
3. The grubs cause damage inside the stem or crown by feeding on soft tissue and often cause severe damage especially when a large number of them bore into the soft, growing parts. In case of severe infestations, the inside portion of the trunk is completely eaten and become full of rotting fibres.
4. In the case of young palms, the top withers while in older palms the top portion of the trunk bends and ultimately breaks at the bend.
5. Sometimes the gnawing sound produced by the feeding grubs inside is audible.
6. In the advanced stage of infestation, yellowing of the inner whorl of leaves occur. The crown falls down or dries up later when the palm is dead.
Management Cultural control:
• All wilting or damaged palms in coconut plantations should be removed and burnt to destroy nesting sites of the pest.Cutting of green coconut leaves should be avoided; if needed, they should be cut about 120 cm away from the stem in order to prevent successful inward movement of the grubs through the cut end.
• Proper spacing of plants is required and over-crowding in bud rot prone localities should be avoided.
Trap method:
Step 1: Specialised buckets with 3 – 4 holes are made and the buckets are wrapped with coconut fibre/jute sack, so that the pests can easily enter.
Step 2: The lure (Ferrolure +) is suspended inside the bucket and 1 litre of water is added along with 100 g pineapple/sugarcane, 2 g yeast and 2 g Carbaryl.
Step 3: The bait buckets are placed at sites where infestation is most observed.
Step 4: After a week, the water is checked for the catch and refilled to prevent mosquitoes from breeding.
Chemical control:
1. Where the presence of the red palm weevils is observed, the bore holes are sealed except the topmost one. Then 1% Carbaryl (20 gm/l) or 0.2% trichlorphon or 0.1% endosulfan suspension at a rate of 1 litre per palm is poured into the hole, using a funnel. The hole is plugged and the process is repeated after 1 week.
2. When the pest infestation is through the crown, the crown is cleaned and the insecticidal suspension is slowly poured in the crown.
3. Where entry of the weevil is through the trunk, the hole in trunk may be plugged with cement or tar.
4. The crown and the axils of the uppermost three leaves are filled with a 2:1 mixture of fine sand and neem seed powder or neem seed kernel powder once every 3 months to prevent the red palm weevil from laying eggs in the area.
