Rhynchophorus ferrugineus (Olivier)

Taxonomic placing: Insecta, Holometabola, Coleoptera, Curculionidae.

Common name: Red palm weevil.

Geographical distribution: South Asia, Australia, Saudi Arabia, the Mediterranean region and Iran, CIE Map #258, 1992 (revised).

Host plants: Palmae, including the sago palm (Cycas revolute Thunb.), the coconut palm (Cocos nucifera Linnaeus) and the date palm, Phoenix dactylifera Linnaeus.

Morphology: The body of the beetle is about 35 mm long, red-brown with a few black spots, and its slender snout or rostrum is 1 mm long. The larva (grub) is apodous, yellow-brown, with a brown head that is bent downwards, up to 50 mm in length.

Life cycle: The weevil deposits its eggs (300-500 per female) in any available wounds on the tree, often in its crown, and all stages live therein. The larvae borrow into the trunk tissues, creating long tunnels and usually pupating under the bark. Adults appear after about 3 months and then live for another 2-3 months. The estimated threshold of development is around 13ºC and in the Middle East the pest completes 2 annual generations. An adult may mate several times, the females finding the males due to a sex pheromone released by the latter. These weevils are strong fliers, capable of covering 1,000 m per day and may thus disperse over large areas, as well as remaining unnoticed within transported date offshoots. The weevil may successfully be cultured on an artificial diet based on banana slices and shredded sugarcane stems.

Economic importance: The red palm weevil is a major pest of date palms in the Middle East and Southeast Asia. Under heavy attack date palms are weakened and die, and yields may be reduced by 90%. The larvae (sometimes over 80/tree) tunnel in the trunk, weakening the tree and bringing about its decline and even breakage under pressure (such as strong winds). In heavily infested date and coconut plantations yields can be reduced by over 90%. Infestations may remain undetected until damage is extensive and such trees have to be destroyed or they topple over in heavy winds. The weevil attacks other Palmae, infesting young trees that had formerly been damaged by other pests, injured through horticultural practices or by natural causes, like storms.

Management

Monitoring: The attraction of the weevil to its aggregation pheromone,supplemented by palm material, is the basis for monitoring its presence. But once established in a plantation, infestation is difficult to detect before much damage had been done, the only visible sign of attack may be the oozing of palm sap from the trunk. Traps consisting of palm stems or petioles may be used to capture flying beetles. Dogs can be trained to smell the ooze from pest-infested trees and have located infested trees that had not been known to be attacked. Another novel method of detecting the pest within date trunks is by “hearing” (acoustic sensing) the larvae therein. An acoustic device is attached to the lower part of the trunk and enables the detection of sounds made by the larvae during feeding.

Cultural methods: Strict quarantine measures are in place in order to limit the spread of this exotic pest. The burning and subsequent burying of infested trees during the early stages of an invasion may reduce weevil dispersal. As the pest deposits its eggs in cuts and wounds, these should be minimized and/or treated with suitable fungicides, followed by the application of an insecticide to prevent egg laying.

Plant resistance: Date palm cultivars differ in their attraction to the weevil and in the extent of its damage, and could be used to select pest resistant or tolerant cultivars.

Mass trapping: Traps loaded with the aggregation pheromone, posted about ten traps/hectare, greatly reduced pest infestations in Israel. Similar traps are being used in many parts of the Middle East.

Irradiation: Egg laying, hatchability and male lifespan were significantly reduced by irradiation, especially under low humidity conditions.

Chemical control: Neonicotinoids and organophosphates, injected into the trees, can control the pest, provided it is detected in time. Trees may also be protected against flying beetles by spraying them with pesticides. Use of fumigant insecticides inserted into infested trunks is unsatisfactory as the penetration of the insecticidal gas is incomplete.

Biological control: Diverse natural enemies, including viruses, bacteria, fungi, mites and insects are associated with the weevil in different regions, but the extent of their controlling effects are largely unknown. In the field several entomopathogenic nematodes killed about 67% pest larvae and adults in Egypt. The entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin caused almost total pest mortality and also greatly reduced the fecundity of the few surviving beetles. Another entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin, killed 20-45% of the beetles in Egypt.

Integrated pest management: The combination of strict quarantine measures, pheromone-based monitoring, mass trapping, sterile male technique, resistant or tolerant date palm varieties, the careful use of pesticides and additional natural enemies may together reduce the damage of this major pest.

References

Abbas, M.S.T., Saleh, M.M.E. and Akil, A.M. 2001. Laboratory and field evaluation of the pathogenicity of entomopathogenic nematodes to the red palm weevil, Rhynchophorus ferrugineus (Oliv.) (Col.: Curculionidae). Anzeiger für Schädlingskunde 74: 167-168.

Al-Ayedh, H.Y. and Rasool, K.G. 2010. Sex ratio and the role of mild relative humidity in mating behaviour of red date palm weevil Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae) gamma-irradiated adults. Journal of Applied Entomology 134: 157-162.

Bozbuga, R. and Hazir, A. 2008. Pests of the palm (Palmae sp.) and date palm (Phoenix dactylifera) determined in Turkey and evaluation of red palm weevil (Rhynchophorus ferrugineus Olivier) (Coleoptera:Curculionidae). EPPO Bulletin 38: 127-130.

Faleiro, J.R. 2006. A review of the issues and management of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Rhynchophoridae) in coconut and date palm during the last one hundred years. International Journal of Tropical Insect Science 26: 135-154.

Faleiro, J.R., El-Shafie, H.A.F., Ajlan, A.M. and Sallam, A.A. 2014. Screening date palm cultivars for resistance to red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae). Florida Entomologist 97: 1529-1536.

Gindin, G., Levski, S., Glazer, I. and Soroker, V. 2006. Evaluation of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana against the red palm weevil Rhynchophorus ferrugineus. Phytoparasitica 34: 370-379.

Mazza, G. (and 10 co-authors). 2014. An overview on the natural enemies of Rhynchophorus palm weevils, with focus on R. ferrugineus. Biological Control 77: 83–92.

Nakash, J., Osem, Y. and Kehat, M. 2000. A suggestion to use dogs for detecting red palm weevil (Rhynchophorus ferrugineus) infestation in date palms in Israel. Phytoparasitica 28: 153-155.

Ortega, L. (and 7 co-authors) 2017. Natural Enemies of Rhynchophorus ferrugineus and Paysandisia archon. In: Soroker, V. and Colazza, S. (eds), Handbook of Major Palm Pests, pp.171-186, Wiley Blackwell.

Salama, H.S., Zaki, F.N. and Abdel-Razek, A.S. 2009. Ecological and biological studies on the red palm weevil Rhynchophorus ferrugineus (Olivier). Archives of Phytopathology and Plant Protection 42: 392–399.

Soroker, V., Nakache, Y., Landau,U., Mizrach, A., Hetzroni, A. and Gerling, D. 2004. Utilization of sounding methodology to detect infestation by Rhynchophorus ferrugineus in palm offshoots. Phytoparasitica 32: 6-8.

Soroker, V. (and 7 co-authors). 2005. Current status of red palm weevil infestation in date palm plantations in Israel. Phytoparasitica 33: 97-106.

Websites: https://www.google.co.il/search?q=rhynchophorus+ferrugineus+picture&biw=1280&bih=687&tbm=isch&tbo=u&source=univ&sa=X&ved=0CB8QsARqFQoTCMTb5Ljh6cgCFUvVGgodfC0GYw http://www.redpalmweevil.com/workshop/Ework.htm