Updates and progress on the sterile insect technique against Aedes albopictus in Italy.

The current Aedes albopictus vector control strategies mainly based on the use of insecticide are insufficient to maintain the mosquito population density below the epidemic risk level or nuisance threshold. The possible integration of the sterile insect technique (SIT) into an area-wide pest management approach is under development and testing to achieve effective suppression. SIT is a biologically-based method of pest control that relies on inundative releases of sterile males to reduce the field population reproduction rate. The continuous release of sterile males could strongly reduce, or even suppress the wild population, especially in those areas where Ae. albopictus is isolated or represents a newly imported invasive species. Mass production must be constantly ensured to guarantee the supply of males throughout the release season and encompass several steps for a cost-effective implementation of this method. Larval and adult rearing is essential since the adults provide eggs to sustain the larval colony and the larval rearing supplies males, needful for SIT program, but also females necessary to maintain the adult colony. Sex separation is also an important aspect, indeed, as females' presence inside the sterile males should be reduced to a minimum. The sex sorting process must ensure an acceptable level of females’ residual presence but also good male productivity and female recovery to sustain the breeding lines. Nowadays, the available sexing methods are only partially mechanized and are swayed by several problems. Even if they are proficient to provide good results, they are not efficient to afford a fully effective separation without any female contamination. The economical sustainability of SIT programs is then strictly connected to the efficiency of mass rearing. The work, here presented, aims to investigate new methods for efficient and reliable sex separation of Ae. albopictus at different stages.