Sterile Rhynchophorus ferrugineus males efficiently impair reproduction while maintaining their sexual competitiveness in a social context

The red palm weevil Rhynchophorus ferrugineus, recently spreading from its native range throughout the world, is one of the most dangerous pests for several palm species. The sterile insect technique (SIT) is a promising environmentally friendly approach for the management of this pest. An essential prerequisite of the SIT is that irradiated males released in nature are as sexually competitive as their wild counterparts. Here we evaluated the potential use of the SIT in red palm weevil males by investigating the sexual competitiveness of gamma-irradiated (Cobalt 60 source, dose 80 Gray) males in the laboratory in a natural-like social context with a balanced sex ratio and by testing their efficacy in impairing female reproduction. Our results showed that irradiation did not affect any of the mating behaviour parameters. However, the male reproductive potential was drastically reduced, as fertility was markedly decreased in females mated with irradiated males. Therefore, an 80 Gray irradiation dose is a promising option for the SIT in the control of the red palm weevil, producing sterile but sexually competitive males when tested in a natural-like mating context.