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Khaled Al-Abdulsalm

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RPW in India

   

A Brief Report on Red Palm Weevil Research in India

 By

Dr.P.S.P.V. Vidyasagar

vidyasagar49@yahoo.com

The Red Palm Weevil Rhynchophorus ferrugineus F. has been identified as an economically important pest of coconut palm (Coccos nucifera) and other palms more than a century back.  In India coconut palms are grown in all the southern states with the highest numbers in the state of Kerala.  The first information on the red palm weevil Rhynchophorus ferrugineus F. was published in 1891 in Indian Museum Notes (1891/3).  This was supplemented by Lefroy in 1906.  This was described as deadly insect pest of coconut palm throughout India.  Ghosh (1912) gave a brief life history of the weevil.  Fletcher (1914, 1917, 1919) described the biology and habits of the pest and suggested the destruction of all attacked dying and dead palms for the effective control in India.  

Madan Mohan Lal (1917) reported it as a serious pest of date palm (Phoenyx dactylifera) in the Punjab region of India.  Meckanna (1918) found considerable damage done by this pest to the date palms in India during 1916-17 and stated that mud enclosures round the trunk of the palms filled with water kept the palms safe from its attack.  However, while giving a brief account of the biology and control measures Venkitasubban (1936) did not consider R. ferrugineus as a serious pest of coconut in Cochin (Kerala).

Economically speaking of the 40 millions coconut palms in Kerala (Cochin/Trivancore area) 0.5% was affected by the pest which accounts to 200,000 palms every year in 1950s in India.  Lever, (1979) in his book reported that in Kerala that nearly 5%  of palms below the age of 10 years were killed annually by this pest.

In young coconut plantations crown, trunk and bole are the natural sites of damage.  In older plantations only crowns are infested.  Many a time the insect completes several generations inside the crown or trunk feeding on the inner tissues until the trunk or crown becomes hollow and tree gets killed. After the death of the palm adult weevils come out and seek fresh trees to attack.  The legless larvae are yellowish, stout and make galleries inside the tree for about 2-4 months.  The adult weevils live for 3-4 months. The females are known to be attracted strongly to the fermenting sap oozing out of wounds in the trunk or the leaf bases. Vidyasagar and Bhat (1991) in their review detailed the research work done on various coconut pests.

Nirula (1956a) studied the biology of the insect in a more detailed way.  He described the physical attributes and duration of different stages viz., egg, larva, pupa and adult.  Besides, feeding behaviour and mating behaviour were well studied.  Male to female ratio was reported to be 1.32:1 by Nirula (1956a).  Males are reported to be predominant in nature.  Fertility of eggs was reported as 79%.  Average larval period was 55 days (36-71 range).  Pupal period was 15 days and adults remained inside cocoon after emergence for about 8 days.  Adult life on an average was 81 days.

 Host plants

            Almost all palms are attacked by RPW.  It is more frequently found in coconut, date palm, sago palm and wild date or toddy palm, Phoenyx sylvestris.  Other palms damaged by the weevil include palmyrah, Borassus flabellifer, oil palm Elaeis guineenis, the talipot palm Corypha umbraculifer, the sugar palm Arenga sacharifera, the sedang palm Livistonia cochinchinensis etc.

 Control measures

Effect of different pesticides against adult and larval stages was studied by Nirula (1956b).  DDT, Benzene hexachloride, Toxaphene, Chlordane, and Pyrethrins- Piperonly butoxide on larvae and adults tested in laboratories and field. The best results were obtained with piperonyl butoxide both for larva and adult stages.

Out of several insecticides tried Pyrocon E 1% when injected into infested trees gave the best results (Nirula, Antonhy and Menon, 1953a).  As prophylactic measure, the leaf axils of young palms may be filled with sand and BHC 5% or chlordane dust in equal proportion as in the case of Oryctes damage. An adult mortality of 92% at 0.5% and 100 per cent at 1.0% concentration of endrin was reported by Mathen and Kurian (1962).

By injecting the infested trees with carbaryl 1.0% nearly 93% palms were cured (Mathen and Kurian, 1967). Subsequently Rao, Subramanian and Abraham (1973) achieved good success by placing aluminium phosphide tablets (fumigant) inside the damaged portion.  Among several insecticides tested trichlorphon 0.2% gave the best results with 92% recovery of infested palms (Abraham, Koya and Kurian, 1975).

Root feeding method was used in some instances for the control of RPW.  In this method monocrotophos or any other systemic insecticide is diluted with water and fed to the infested palm through the active root.  The insecticide is absorbed and translocated to all parts of the plant resulting in the death of active feeding stages of the insect.  However, in this case the pupal stages would escape from the effect of the pest.  Another aspect which is of concern with this method is the pesticide residues in the tender coconut water and kernel.  Hence this method is discouraged.

 Biological control

In India no Scoliid wasp has been found to parasitize RPW larvae at any stage.  Mites are seen on pupae and adults.  About three species of mites have been described from the body of the insect.

            A few pathogens were tried against the immature stages of the RPW in India.  However, none of them was effective in the field.

 Trapping with Food baits

A trap for the collection of R. palmarum was developed by Maharaj (1965) in Trinidad.  When this method consisting of traps with split fresh coconut petioles was tested in one estate in Sri Lanka 302 red palm weevils (R. ferrugineus ) were recovered from 10 traps in 141 days (Ekanayake 1970).  The trapping method was modified with the addition of sugarcane and yeast to the split petioles.  By mixing the traps with BHC 50WP (2g/trap) the trapped weevils could also be killed (Anonymous, 1988).

 Sterility technique

Attempts have been made to develop control measures against RPW making use of the sterile insect techniques with radioisotopes (Kloft et al, 1986: Kloft, Koerner and Wolfram, 1986).  However, the results on the application of this technique in the field and its success are not available from any country. 

The Bhaba Atomic Research Council (BARC) (India) (1980s) in collaboration with CPCRI conducted a number of studies on the sterile insect techniques.  They have found the exact amounts of radiation required to sterilize an adult weevil and its effect on the mating behavior.  However, due to practical difficulties the methods could not be taken to the field.

 Electronic Detectors

As the early detection of the damage in a palm is difficult some attempts have been made to develop simple electronic device for detecting infestation.  The principle involved in the amplification of the chewing noises generated by the grubs inside the trunk of a palm.  After a series of experiments some electronic devices were developed for detecting the noises(Anonymous, 1989).  Again the difficulties encountered in the field testing did not allow further development of such devices.  More recently some German firm has developed such sound amplification devices for detecting the insect inside the trunk.

 Pheromone trapping techniques

            Much before the identification and synthesis of the male aggregation pheromone of R. ferrugineus preliminary studies were conducted for the presence of sex pheromones in the RPW in India (CPCRI).  As the techniques used were not advanced the results could not be used.

            The male aggregation pheromone of RPW synthesized by the Canadian researchers was extensively field tested in 1990s in the Gulf countries especially the Kingdom of Saudi Arabia. I had the privilege of conducting a large number of field trials and developed methods for the use of pheromone traps and integrate them in the IPM.   

            In India also the same pheromone lures were field tested and best trap was developed for attracting the optimum number of adult weevils.  The trials involved the development of the best trap design, trap height, food source, and the trap density (Vidyasagar et al, 2001 unpublished).  The last item mentioned here the trap density is very important for a successful campaign with trapping.  We were able to suggest the best trap density in coconut gardens.

            At present many labs are involved in the development of pheromone lures indigenously.

 Bibliography

Abraham, V.A., K.M. Abdulla Koya, and Chandy Kurian. (1975). Evaluation of seven insecticides for control of red palm weevil Rhynchophorus ferrugineus Fabr. J. Plantation Crops. 3:71-72.

Anonymous (1988) CPCRI Annual Report for the year 1987.

Anonymous (1989). CPCRI Annual Report for the year 1988.

Eknayake, U.B.M. (1970). Report of the crop protection officer. 1969. In Ann. Report. C.R.I. Ceylon Coconut Q. 21:56-59.

Fletcher, T.B. (1914). Some South Indian insectrs. Govt. Prss. Madras.

Fletcher, T.B. (1917).  ferrugineus Proc. II. Ent. Mtg. Pusa.

Fletcher, T.B. (1919). Rhynchophorus ferrugineus Proc. III. Ent. Mtg. Pusa.

Gosh, C.C. (1912). The rhinoceros beetle and red or palm weevil. Mem.Department of  Agriculture, India II.

Kloft, W.J., E.S. Kloft, P. Kanagaratnam, P. and J.L.J.G. Pinto. (1986). Studies on the use of radio isotopes for the control of the red palm weevil, Rhynchophorus ferrugineus F. by the sterile insect technique1. Preliminary investigations on the detection of radio labeled weevils. Cocos, 4:11-17.

Kloft, W.J., J. Koerner and E. Wolfram. (1986). Studies on the use of radioisotopes for the control of the red palm weevil Rhynchophorus ferrugineus F. by the sterile male insect techniques. Cocos. 4:19-22.

Lefroy, H.M. (1906). The more important insects injurious to Indian agriculture. Govt. Press, Calcutta.

Lever, R.J.A.W. (1979). Pest of the coconut palm. FAO Plant Production and Protection Series No.18. pp.190.

Madan Mohan Lal (1917). Report of Assistant Professor of Entomology, Dept. Agri., Punjab for year ended 30th June 1917.

Maharaj, S. (1965). A new design for collecting the palm weevil, Rhynchophorus palmarum L. Trop. Agric. (Trinidad). 42: 373-375.

Mathen, K. and C. Kurian (1962). Comparative efficacy of different insecticides on Rhynchophorus ferrugineus F. p464. In Proceedings of the First conference of Coconut Research Workers in India, 1959. Indian Central coconut committee, Ernakulam.

Mathen, K. and C. Kurian (1967). Insecticidal trials against Rhynchophorus ferrugineus Fabr. (Curculionidae, Coleoptera), the red weevil of coconut, Indian J. Agric. Sci. 37: 521-523.

Meckanna, J. (1918). Report on the progress of agriculture in India for the year 1916-17. Govt. Press, Calcutta.

Nirula, K.K. (1956a). Investigation on the pests of coconut palm. Part IV. Rhynchophorus ferrugineus F. Indian Coconut Journal. No.9: 229-247.

Nirula, K.K. (1956b). Investigation on the pests of coconut palm. Part IV. Rhynchophorus ferrugineus F. Indian Coconut Journal. No.10:28-44.

Nirula, K.K. Antony, J., and Menon, K.P.V. (1953). The palm weevil and its control. Proc. 40th Indian Science Congress.

Rao, P.V. Subba, T.R. Subramanian, and E.V. Abraham, (1973). Control of red palm weevil on coconut, J. Plantation Crops 1: 26-27.

Venkitasubban, C.S. (1936). Pests of coconut palm.  Dept. Agri. Ento. Scr. Bull. Cochin.

Vidyasagar, P.S.P.V. and S. Keshava Bhat. (1991). Pest management in coconut gardens. Journal of Plantation Crops 19(2):163-182.

Vidyasagar, P.S.P.V., B.M. Mohammed Basheer, and K.Subaharan, 2001. Bioefficacy of pheromone-based trapping for Red Palm Weevil, Rhynchophorus ferrugineus Oliv. management in coconut gardens. (communicated).

 

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