The control of Vespa velutina populations has been performed in many European countries since the species was introduced in 2004, in order to limit its expansion and impacts. The controlling methods are based mainly on the capture of adults with traps and on nest detection and destruction; the latter method seems to be the most effective method to control Vespa velutina populations. However, their nests are often difficult to be observed, especially those built in woodland areas and covered by leaves until late autumn, a time when the future queens may have already left the nest.
For this reasons, it has been necessary to develop a new monitoring technic that allows to detect Vespa velutina nests before the fall of the leaves and the emerging of new founder queens.
The entomological radar
The LIFE STOPVESPA partner “Politecnico di Torino” has developed two harmonic radar prototypes that allows to detect Vespa velutina’s nests by capturing adults (e.g. during their hunting activity in apiaries) and tracking their flights back to the nests. The harmonic radar emits waves in the environment at 9,41 GHz, which are than reflected by non-linear devices (e.g. a tag set on a hornet) at 18,82 GHz and then detected again by the radar itself. The tag is a simple and very light metallic wire with a diode, which reflects the waves emitted by the radar. The captured hornets are immediately released after the application of the tag. The latest version of the prototype has an operating range of about 500 m and can be easily moved to follow tracks behind obstacles.The monitoring teams, equipped with the entomologic radar, operated during these years detecting several nests of Vespa velutina. The use of the entomologic radar was fundamental in new outbreaks, such as the areas of Finale Ligure and La Spezia, where several colonies have been detected in a short period of time. Once discovered, nests are reported to the destruction teams of the project, which rapid act to inactivate and remove them.
Many beekeepers and stakeholders were able to assist in different occasions to the radar activity sessions, in particular during two workshops organized by the LIFE STOPVESPA project respectively near Ventimiglia and La Spezia.