Bioécologie, Cartographie et Identification de foreur rhinocéros l’Oryctes spp. du palmier dattier (Phoenix dactylifera L.) dans la région d’El Oued, Algérie.

Abstract

This study focuses on the rhinoceros beetle Oryctes spp. of date palms, conducted at Taleb Larbi and Douar El Ma sites in El Oued, Algeria, over a two-year period (2022-2024), it aims to understand the biological and ecological aspects of of this pest. Observations in the natural environment reveal that Oryctes agamemnon follows a univoltine life cycle, with the flight period starting in April and extending until December, with the adult population peaking in August. Adults hibernate from January to March, while the larvae, present at all developmental stages throughout the year, continue to develop. Laboratory studies, conducted at a temperature of 26 ± 1°C, humidity of 55 ± 5%, and a photoperiod of 13/11 hours, show that the complete life cycle of Oryctes agamemnon lasts approximately 314.87 ± 7.79 days, with the larval stages accounting for 66% of the total cycle. Among these stages, the third larval stage is the longest, lasting on average 124.58 days. The results also indicate a maximum mortality rate at the embryonic stage, reaching 20.45%. Both adults and larvae of Oryctes cause significant damage to date palms. The larvae primarily attack the roots and trunk, tunneling through and damaging the structure and growth of the palm. Adults also target the trunk and can reach the crown, perforating and damaging the plant tissues, weakening the tree. These activities compromise the health of the palm, promoting severe infestations and threatening its survival. The identification of mites associated with Oryctes agamemnon subsp. arabicus led to the discovery of a new species of mite from the Laelapidae family, Hypoaspis arabicus Rais and Kontschán, sp. nov. (Acari: Laelapidae). This mite species was observed throughout the various developmental stages of the insect. Analysis of the NDVI index at the study sites from 1990 to 2024 shows a general upward trend. However, a stabilization of values has been observed since 2012. This stabilization could be linked to the emergence of the pest Oryctes agamemnon, whose negative impact limits vegetation growth and slows the evolution of the NDVI index. The identification of Oryctes specimens was carried out using morphological and molecular methods with the COI marker, confirming that all individuals belong to the subspecies Oryctes agamemnon subsp. arabicus, with slight genetic diversity observed among populations through MASH analysis. These results offer insights for developing integrated pest management strategies and tailoring interventions to the biological cycle of the species. This will help protect local date palm plantations from damage caused by this pest, thus contributing to the sustainability of date palm cultivation in the region.