Photographer:Unknown Affiliation: Pest and Diseases Image Library Source:www.bugwood.org Copyright:CC BY-NC 3.0
Adult Description: The adults of Oryctes rhinboceros are large and stout beetles that can measure up to 35mm long and 21mm wide. They are black or reddish-black in color, and have a characteristic horn which is larger in males (pictured below; male beetle on the right). The posterior end (pygidium) is densely covered with reddish brown hairs on the ventral surface in the female which helps in distinguish it from the male.
Larvae Description: Larvae are white and c-shaped with brown legs and head.
Host Plant: Coconut, palm, pineapple, papaw, taro and date trees, and sugarcane.
Symptoms of beetle infestation are damage to the center of the crown and the developing leaves growing out with a V-shape due to the feeding path from the larvae. A moderate infestation can reduce nut production and a strong infestation can cause dieback and eventually death to the plants. Several of these plants are economically and ecologically important for Hawaii. Moreover, the beetle is able to also infest sugarcane and palms which means if this beetle were able to make it to the continental United States it could severely impact Texas, Louisiana, and Florida crops and native palm plants. On other islands in the Pacific, this beetle has been documented to destroy over 50% of coconut palms present on the islands.
Females burrow into rotting stumps, standing trees or debris piles (such as sawdust or compost) to lay whitish-brown eggs. Eggs take 8 to 12 days to hatch. After hatching, the insect goes through 4 instar stages (totaling 90 to 220 days) before enter pupation that lasts 17 to 28 days. From egg to beetle the total life cycle lasts 4 to 9 months, meaning that more than one generation per year can occur.
Accidental introduction into Samoa from Sri Lanka in 1909 presumably happened by seedling pot plants being imported into Samoa. It then reached Guam in 2007 and spread to all urban and suburban areas by 2012. Since then it was discovered in Oahu, Hawaii in December 2013. It was thought to have spread throughout Samoa by compost and rotting breadfruit/banana that is sued for earth ovens. It has been found aboard aircrafts amongst live plant tissue flasks being imported from Southeast Asia. The interisland transport of people, plants, and fruits has facilitated the spread of this beetle.
U.S. Habitat: Anywhere with higher humidity levels and where the host plants are able to grow.
U.S. Present: Hawaii, Guam, and American Samoa
To control Oryctes rhinoceros an integrated pest management consisting of mechanical, chemical, and biological methods is necessary. The mechanical aspects are examining trees for infestation and removing the beetle physically. Chemical methods that can be used as prevention. Suggested methods are pesticides and/or napthalene balls to repel the beetles. Oil cakes of neem and marotti (Hydnocarpus wightiana) have also provided good results. In several of the areas where this beetle is native to there is a green Muscardine fungus (Metarhizium anisopliae) that is able to kill the larvae and is used as a biological control. It is able to kill the pest in low temperature and high humidity conditions. There is also a viral pathogen called Baculovirus of Oryctes (OBV) and it can kill the larvae within 15 to 20 days of inoculation. It also affects the reproductive abilities and longevity of the adults. Thankfully, in native habitats this beetle has several predators that feed on the eggs and early instar larvae of the beetle. The important predators are Santalus parallelus, Pheropsophus occipitalis, P. lissoderus, Chelisoches morio. However, using these predators in invaded territories is not ideal, since their impact on those habitats are not known. Trapping this beetle is quite easy and one can use rotting castor cake slurry kept in mud pots. There are also black cross-vein traps that are hung in trees as part of a survey program in Hawaii on the Joint Base of Pearl Harbor and Hickam where the beetle was found.
To see the integrated management packet compiled by Dr. Chandrika Mohan click here.
Bedford, G.O. 1980. Biology, Ecology and control of palm Rhinoceros beetle. Ann. Rev. Entomol, 26, 213.
Kurian, C., Pillai, G.B., Antony, J., Abraham, V.A. and Natarajan, P. 1983. Biological control of insect pest of coconut. In. Coconut Research and Development. Proc. of the International Symposium I. CPCRI, Kasaragod. Dec 27-31, 1976. (ed. N.M. Nair) Wiley Eastern. New Delhi p.361-375. Print.
Nirula, K.K., Antony, J. and Menon, K.P.V. 1952. The rhinoceros beetle (Oryctes rhinoceros L.) life history and habits. Indian Cocon. J.V (2).