RED PALM WEEVIL

Classification

Phylum
Arthropoda (Arthropods)
Class
Insecta (Insects)
Order
Coleoptera
Family
Curculionidae
Species
Rhynchophorus ferrugineus Oliv

Distribution: India, Ceylon, Middle East countries, Thailand, New Guinea, Spain and Philippines

Main Host: Coconut (fatal enemy)

Alternate Host: date palm, Areca, Caryota, Coelococcus, Nypa palm, palmyrah and oil palm

Occurrence: round the year but becomes severe after monsoon

Life Cycle:

The female commences oviposition 1 to 7 days after mating. It deposits the eggs after scooping out the tissues. Creamy white, long and oval shaped eggs hatch in 2 – 3 days time. The egg measures 2.62 mm in length and 1.12 mm in width. The pre ovipostion period lasts for five days and the ovipostion continues for 25 – 65 days. An individual female lays up to 276 eggs. Incubation period ranges from 2 – 3 days.

The grubs are whitish and apodous with a swollen median; the head is armed with strong mandibles. The grubs tunnel the inner tissues and feeds on them. The grub period ranges from 36 – 78 days. The grub forms a cocoon with the vegetal debris and the pupal stage lasts for about 12 to 33 days.

The adult weevil is ferrugineously brown with long curved and pointed snout. The males are differentiated from females by a tuft of hairs on dorsal side of the snout. The life cycle is completed in four months and the females are short lived than males.

Damage:

Being an internal feeder, it is very difficult to detect the damage caused by red weevil at an early stage. Wilting of the central spindle, presence of chewed fibers and cocoons in the trunk, presence of holes in the trunk with brown fluid oozing out are the important symptoms of red weevil attack. The symptom of their infestation becomes clear in advanced stages, the time at which the crown of the affected palm topples. The weevil multiplies enormously in young coconut plantations causing loss to an extent of 5 – 10 per cent.

 

Management:

  • Avoid causing injury to the palms, as they would attract the weevil to lay eggs. Injuries caused by rhinoceros beetle, mechanical injury during cutting of leaves or steps cut on the trunk for climbing give a favorable condition for egg laying. Infection by fungal disease is also a predisposing factor. Mechanical injury if any caused should be treated with coal tar and carbaryl.
  • Periodical crown cleaning is to be done to avoid decaying of debris in leaf axils.
  • While cutting of fronds, petiole to a length of 120 cm is to be left from the trunk to prevent the entry of weevils into the trunk.
  • Removal and burning of palm with advanced stage of infestation would aid in destruction of various stages of the pest harbored in the trunk.
  • Prophylactic leaf axil filling suggested for rhinoceros beetle may be attempted.
  • Palms showing early stage of infestation may be subjected to curative treatment with 0.1% dichlorvos or 1% carbaryl. If damage occurs in the crown, the damaged tissue has to be removed and insecticide suspension may be poured in. In case of entry of weevil through the trunk, the hole in trunk may be plugged with cement / tar. A slanting hole is made with the aid of an auger and the insecticide solution is poured with funnel.
  • Log trapping with toddy

Fresh coconut logs of 50 cm length are split longitudinally and the cut surfaces smeared with toddy fermented with yeast or acetic acid. The traps are setup by placing the toddy treated split logs one above the other with the cut surfaces facing each other. The log so kept is effective in attracting the weevils.

Coconut petiole pieces smeared with fermented toddy kept in pots @ 10 pots / ha. serve as weevil traps. The traps should be placed at dusk and the weevils trapped are destroyed next morning.

  • Mud pot trapping with molasses: mud pots containing sugarcane molasses 2.5 kg or toddy 2.5 lit. + Acetic acid 5 ml + yeast 5g + longitudinally split tender coconut stem are to be placed @ 75 Nos./ha.
  • Pheromone traps:

To a plastic bucket of 5 lit., four windows (5x1.5 cm) are made below the rim of the bucket. Coconut fiber / jute sack is wound over the bucket to provide grip to the alighting beetles. The commercially available pheromone lure (Ferrolure +) is hung inside on the lid of the bucket. The bucket is filled with 100 gm pineapple / sugarcane, 2 gm yeast, and 2 gm carbaryl in 1 lit. of water. The traps are tied on the palm trunk at about 1.5 M above the ground level. Placing a single trap / ha. was found to beideal. This technology would be successful if taken up on community basis.

An earwig Chelisoches moris F. (Forficulidae) predates on the eggs and early instar grubs of red weevil.

Bioinformatics Centre & Library CPCRI Kasaragod