Oryctes agamemnon (Burmeister)
Common name: Rhinoceros beetle.
Taxonomic placing: Insecta, Holometabola, Coleoptera, Scarabaeidae.
Geographical distribution: The Middle East to Iraq, Saudi Arabia, the Persian Gulf, North Africa.
host plants: The date palm, the coconut (Cocos nucifera Linnaeuus and lawn grasses.
Morphology: The adults are 30-35 mm long, dark brown, and the male has a horn on its head (thus “rhinoceros beetle”). The prothorax bears a large rounded depression, with a single protuberance in the female, two in the male. The larva (commonly called grub), which reaches a length of 70 mm, is whitish, with a brown head and legs.
Life cycle: The adults emerge in spring, each female producing about 30 eggs. The larvae hide and tunnel in dead and live tree tissues, staying there without diapause, pupating in early spring, raising a single annual generation. At 24ºC and 75% relative humidity the development of a generation requires 140-210 days. The beetles fly at night for short distances and shelter during day in their development sites. They feed occasionally on the juice extracted from respiratory roots. They are nocturnal and gregarious, most larvae being concentrated at the level of the collar and the root system. They also bore into the soft tissue of frond rachis at the tree crowns. Their populations peak during mid-summer.
Economic importance: This beetle is one of the most important pests of coconut and oil palms in South and Southeast Asia. The tunneling of the adults and larvae into the tree causes damage to inflorescences and reduces photosynthesis, which decreases or delays fruit production. It also facilitates the invasion of rot fungi. Boring in the trunk may cause wilting and weakening of young trees, causing their decline and even possible uprooting by strong winds. Mature palm trees may likewise be killed. The most severe damage is caused by larval infestations of the respiratory roots at the soil level. The beetles also damage lawn grasses by feeding on their roots.
Management
Cultural control: Mass trapping by light traps, and the removal of dead plant material (including felled trunks) may reduce adult populations. Covering infested trunks with a rapidly growing ground cover.
Monitoring: Specially constructed vane traps baited with the beetle’s aggregation pheromone can be used for this purpose.
Chemical control: Various pesticides, like organophosphates or carbamates are sometimes recommended for controlling the pest. They are to be applied as a drench around the trunk, in mid-summer to affect the maximum number of larvae, or used as drenches onto manure, stumps and other organic matter, which are colonized by the pest.
Biological control: Limited success in managing the pest may be achieved by introducing a baculovirus, which reduced beetle numbers in the Philippines to 10-20% of prerelease levels. This baculovirus is effective only if it infects new larval hosts or is repeatedly applied. Several mites are associated with the pest, but their effect is not clear.
References
Al-Deeb, M.A., Bin Muzaffar, S. and Mohammad Sharif, E. 2012. Interactions between phoretic mites and the Arabian rhinoceros beetle, Oryctes agamemnon arabicus. Journal of Insect Science 12: 128.
Eitam, A. and Ucko, O. 1993. Oryctes agamemnon (Coleoptera: Scarabaeidae): a pest of date palms and lawns in the Arava valley. Hassadeh 73: 550-551 (in Hebrew with an English Abstract).
Ehsine, M., Belkadhi, M.S. and Chaeib, M. 2009. Bio-ecologic observations on rhinoceros beetle Oryctes Agamemnon (Burmeister 1847) on the palm dates oasis of Rjim Maatoug in South-western Tunisia. Journal of Arid Land Studies 19: 379- 382.
Hallet, R.H. (and 8 co-authors) 1995. Aggregation pheromone of coconut rhinoceros beetle, Oryctes rhinoceros (L.) (Coleoptera: Scarabaeidae). Journal of Chemical Ecology 21: 1549–1570.
Soltani, R. 2010. The rhinoceros beetle Oryctes agamemnon arabicus in Tunisia: current challenge and future management perspectives. Tunisian Journal of Plant Protection 5: 179–193.
Soltani, R., Lkbel, C. and Habib Ben Hamouda M. 2008. Descriptive study of damage caused by the rhinoceros beetle, Oryctes Agamemnon, and its influence on date palm oases of Rjim Maatoug, Tunisia. Journal of Insect Science 8: 1-11