Dr. Vidyasagar

Link: http://esa.confex.com/esa/2011/webprogram/Session15514.html

Prof. Vidyasagar, P.S.P.V

We now know that more concerted efforts are needed by the governmental agencies as well as the private organizations and the growers to solve this problem.  On our part the Chair of Date Palm Research (formerly Red Palm Weevil Research Chair), King Saud University, has embarked on a new strategic research plan and is cooperating with other institutes, universities and Ministries.  We have to bring together all the knowledge and expertise available from any corner of the world to tackle this vexed problem.  Due to my preoccupation with regular duties I have not been able to blog regularly; however, I continued to reply directly to many readers who have a problem or two with the control of red palm weevil.  I am addressing the minor glitz in posting of messages and soon it will be over and all postings will be visible from the new year under appropriate subheadings.  I hope to continue this blog more regularly for the benefit of all my readers.  I also request other friends and readers to write and share more information about the red palm weevil to enrich the knowledge base of others. I once again wish you all a Fantastic and Rewarding New Year.

We have deviated quite a bit away from our main topic of discussion.  Here the point we want to know is whether the report of R. ferrugineus from Curacao is correct or not.  If somebody is expressing doubts, then it should be cleared beyond any iota of doubt.  For this purpose, we need to know complete details about this matter, from a cross section of people belonging to this particular region especially Gerard van Buurt and also Hugh.  Once it is confirmed that RPW, R. ferrugineus indeed is present, then all palms including imported date palms (ornamental) and also coconut palms abounding in the region should be monitored by the local authorities.

Next point that comes to mind is the distribution and coexistence of two species of palm weevils, R. palmarum and R. ferrugineus at the same place.  If so, which one is more dominating and how is the newly reported species finding its feet in the new region? What are its preferred host plants?  Likewise several other aspects need to be explored by researchers and the stake holders like farmers, landscapists, policy makers etc should be informed about the ill effects of the new species in their environment.  Public and private sector should work together in tackling this problem more effectively.  Not only this but other countries in the region should be alerted and a regional conference called immediately to address the impending problem.

Although stringent international quarantine laws are in place, there are several loopholes in the procedures and methods adopted.  Certainly FAO /IPPO/EPPO can initiate action in coordinating the regional groups and expert panels to recommend tangible actions.  However, it is the responsibility of individual governments to take appropriate action in arresting the spread of this menace.

 Eggs

 Early instar larvae

 Middle instar grub in partially fed sugarcane bits

 Pupa (fibrous cocoon removed)

 Rearing in sugarcane bits

 Rearing adults (split sugarcane bits removed)

 Damaged coconut palm cut to show exit hole marks

 Damaged coconut palm cut to show various stages of grubs (inset enlarged grubs)

 Toppled coconut palm crown due to severe damage

 Red Palm Weevil damage resulting in fall of young Date Palm 

 Coconut Palm with bunches

 Date Palm bearing profusely

 Dr P S P V Vidyasagar in lab

Palms around the world are ruthlessly attacked and damaged by the Red Palm Weevil.  It targets coconut, date, oil and other palms causing great economic loss to the growers.  In some countries it not only causes direct losses but also  transmits diseases as a vector of dreaded red ring disease in oil palm in latin American countries.

The red weevil is reported to be a native of south Asia but surprisingly no natural enemy of any consequence is noticed in this part.  Perhaps that is the reason why the pest has spread to newer  regions in the past two decades at a phenomical speed.  As the scientific community makes concerted efforts to suppress the pest, evidence is emerging about the occurrence of the pest from newer areas and continents.

On a evolutionary basis, it is safe to say that the red palm weevils are divided in to several species.  The ones present in Asia especially India, Sri Lanka, Malaysia etc are categorized as Rhynchophorus ferrugineus Oliv.  The species found in Americas is R. palmarum and the one in Africa is R. phoenicious.

Recent advances in biotechnology have facilitated the understanding of evolutionary biology of various species or varients of Rhynchophorus species.  It is hoped that the information gathered on these lines will ultimately help the biologists to understand the intricate mechanisms of evolutionary genetics and lead to more effective means of managing these pests.  An interesting area for intensive research is the palm weevil genomics.  The studies will pave the way for the application of novel methods of control in future.

Prevention is better than cure.  So it is always advantageous to restrict the entry of the weevil stages into the palms.  As a prophylactic measure, young palms may be soaked with a pesticide at periodic intervals.  This will kill the hidden adults in the palm crowns and also any pest stages present in crevices and damaged tissues.

 1. Soaking or drencing method

2. Cultural practices

It is very interesting to note that the cultural practices followed by coconut and date palm farmers/growers vary widely in different countries and regions.  During my travel in Thailand, I noticed a place with tall coconut palms with most of their leaves pruned as seen in the picture below.  Only 3-5 inner leaves were left on the palms and the palms presented a pathetic sight.  No doubt it is not a common practice but it should be avoided by all.  In coconut it is always recommended to allow maximum leaves so that the annual nut yield is fairly good and economical.  One must avoid premature cutting of leaves and if a leaf has to be cut, care should be taken to cut only the outer most one or two leaves with 2-3ft of leaf bases intact.  The leaf bases will slowly dry up and drop off in due course of time.  There are a couple of advantages in this cultural practice. One is that there is no injury as such to the palm and the second one is that it prevents the entry of newly hatched larvae of Red Palm Weevil into the plant.  The long leaf base or petiole was found to act as a barrier for the early instar grubs which find it difficult to tunnel up to the soft tissues of the stem.  So it is advised that farmers and growers should follow this method to prevent the Red Palm Weevil attack in coconut palms.

3. Phytosanitation

4. Plant Quarantine

5. Pheromone Trapping System



2. Rhynchophorus palmarum  (L) -    Mexico, Central and South America

3. Rhynchophorus cruentatus (F)  -  Florida, the coast of south-eastern USA, South Carolina to Texas

4. Rhynchophorus vulneratus Panz   -  Far East Asia

5. Rhynchophorus phoenicis (L)   -  Central and Southern Africa

6. Rhynchophorus bilineatus  -  New Guinea

7. Dynamis borassi (L)     -      South America mainly  Ecuador, Colombia, Brazil

8. R. quadrangulus     -   West-Central Africa

Most important palms are Coconut palm, Date palm and Oil palm.