Seasonal and Nocturnal Activities of the Rhinoceros Borer (Coleoptera: Scarabaeidae) in the North Saharan Oases Ecosystems

The rhinoceros borer Oryctes agamemnon Burmeister (Coleoptera: Scarabaeidae) is a date palm insect pest that causes damage to trunk and roots of palm trees in several countries, including Tunisia, the United Arab Emirates (UAE), Oman, and Saudi Arabia. The aim of this study was to monitor the seasonal and nocturnal activities of this beetle. Experiments were performed on a date palm of Rjim Maatoug during a 6-yr period (2004-2007, 2009-2010). Field survey using light traps shows that O. agamemnon is a univoltine, with a single population peak. Adults appear in the field around late May-early June and the population continued to build until maximum numbers are reached between the end of July and the beginning of August in the same year. No adults were found after first 10 d of November. This peak was characterized by female dominance in number. The monitoring of nocturnal activity showed that it starts its activities roughly 40 min after the sundown and continues until approximately 1 h before sunrise. The highest number of trapped beetles was remarked in the two first hours of flight activity, with a dominance of female in the first hour and a dominance of male in the second hour. We remarked that the sex ratio (female:male) of the cumulated number of trapped adults in the different years and nights of survey was in favor of females.