Effects of γ-Irradiation on Mating Behavior of Red Palm Weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Dryophthoridae)

SIMPLE SUMMARY: Red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier, 1790) is a highly invasive species of Southeast Asia and Melanesia origin that has spread widely in the Middle East and the Mediterranean area. Its larvae cause extensive damage to several palm species in the Arecaceae family, many of which are economically important for agricultural and ornamental purposes. For this reason, many studies are investigating sustainable and effective management strategies, including the Sterile Insect Technique (SIT). In this study, behavioral bioassays have been carried out in laboratory to evaluate if sterile RPW adult males are able to sexually compete with fertile males in no-choice and choice conditions. Results confirmed that irradiation does not induce any negative effects on the mating behavior and performance of sterile RPW males. ABSTRACT: Red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier 1790) is a highly invasive species originating from Southeast Asia and Melanesia. Over the past 30 years, this alien pest has spread extensively in the Middle East and the Mediterranean basin. Its endophagous larvae feed on various palm species, causing significant damage that leads to the death of palm trees. Controlling RPW infestations is challenging due to their gregarious nature and the lack of detectable early symptoms. Systemic insecticides are effective means of control, but their use in urban areas is prohibited and resistance can develop. Considering alternative options with minimal environmental impact, the Sterile Insect Technique (SIT) has been explored. Previous research has shown that male RPWs irradiated at 80 Gy or higher achieve full sterility. This study aimed to investigate in laboratory conditions whether RPW sterile males (irradiated at 60 and 80 Gy) could compete sexually with non-irradiate males. Laboratory bio-assays under both no-choice and choice conditions assessed sexual performance in terms of number of matings, mating duration and time elapsed until the first mating. The results confirmed that irradiation does not negatively affect the mating performance of sterile males, demonstrating their ability to compete successfully with non-irradiated males in both experimental setups.