Use of the sterile insect technique against Aedes albopictus in Italy: First results of a pilot trial

In Europe, the mosquito Aedes albopictus (Skuse) is widespread in Italy, Albania and most probably in neighbouring Montenegro. Recent introductions have also been reported in France, Spain and southern Switzerland. In Italy, the species is currently recognized as the most noxious mosquito, thus requiring the implementation of intensive control programmes. Ae. albopictus is also a potential vector of human diseases, which has raised the issue of whether eradication campaigns are called for. This species is particularly suitable for application of the sterile insect technique (SIT) because of its urban-related distribution, recent introduction, low active dispersal potential, low population density which may be maintained by conventional control measures, and ease of mass-rearing. In 1999, a programme was initiated that focused on the application of the SIT against Ae. albopictus. A pilot rearing facility, targeted at the production of up to 20 000 male pupae per week has been established. Blood feeding is performed with a thermostatically controlled device using defibrinated bovine blood, egg hatching is stimulated with a nutrient broth culture, and egg counts conducted automatically. Larval density and larval diet are still being investigated in order to improve productivity, the separation of males is currently conducted at the pupal stage using calibrated metal sieves, and irradiation studies are performed at the 60Co plant Calliope, Italian National Agency for New Technologies, Energy and the Environment in Rome. During the summer of 2004, eight weekly sterile male pupal releases were organized in Rimini to evaluate sterile male performances in the field against a natural population. A significant difference was observed in the release area compared with the control area when the effects on egg fertility and egg density were cumulated. It is planned to continue the programme on a larger scale to improve rearing efficiency and obtain a preliminary benefit/cost evaluation.