Descriptive study of damage caused by the rhinoceros beetle, Oryctes agamemnon, and its influence on date palm oases of Rjim Maatoug, Tunisia

摘要

Oryctes agamemnon (Burmeister 1847) (Coleoptera, Scarabaeidae) was accidentally introduced in the southwestern oases of Tunisia (Tozeur) around 1980 and spread to the Rjim Maatoug region. In these areas O.agamemnon was specific to date palm trees causing severe damage that can result in potential danger due to collapse of the tree. This study was conducted from April 2004 to March 2006 in 4 sites in the region of Rjim Maatoug. Different levels of palm tree attack were determined, ovioposition sites were identified, and pest damage was described in detail to specify their relative importance and to indicate factors governing palm tree attack. Eggs were individually oviposited in the attacked parts. Dead parts of palm trees were the main target of O. agamemnon including the respiratory roots, tough, trunk bark, dry petiole and the periphery of the crown. The crown itself was not attacked. Feeding by larvae caused significant damage. The biggest danger occurred when heavy attacks of larvae invaded the respiratory roots at the level of the soil, and secondarily on the periphery of the crown, which can result in fungal diseases. Several cases of Deglet Nour date palm tree collapse were caused by this pest in Rjim Maatoug. Attacks on other parts of the tree were without danger for the palm tree. In the absence of pest management, application of a quarantine program combined with field cultivation techniques could help farmers significantly decrease attack of O. agamemnon on palm trees.