Preliminary studies of the biological cycle of the red palm weevil (Rhynchophorus ferrugineus) in Italy, aimed to the application of sterile insect technique

Red Palm Weevil (RPW), Rhynchophorus ferrugineus, native of southern eastern Asia, is a major pest of palm species, including cultivated, ornamental and spontaneous plants. Adult females oviposit inside young leaves or in wound of the trunk and larvae bore the palm trees leading to their death. The goal of this work, financed by the IAEA (Vienna, Austria), is to assess the feasibility of the application of Sterile Insect Technique (SIT) in an IPM to control populations of RPW. In this context, our interest has been focused on two aspects: the study of fecundity and fertility of wild individuals and study of the mating system through genetic analyses. For the first target, adults, mature larvae and cocoons were collected in the field. Under laboratory conditions, virgin females were able to lay eggs, although their number was significantly lower if compared to mated females. As expected, the fertility of these eggs was zero. For the second purpose molecular markers (microsatellite loci and SNPs) are under development. The knowledge of the reproductive biology of the pest is a critical issue in order to correctly plan any SIT program. The cited molecular markers will help to evaluate the mating system and the population structure of the RPW (e.g. polyandric behavior, inbreeding levels, gene flow and population size estimates). These data will strongly contribute to clarify the biological cycle of the RPW and will represent the required background to plan future SIT projects to control or eradicate this noxious species in Mediterranean areas.