Testing the selectiveness of electric harps: a mitigation method for reducing Asian hornet impact at beehives

The Asian hornet (Vespa velutina) has rapidly become a source of stress for the beekeeping sector. Several methods have been developed to control its impact and spread, though some of these impose a high risk for native insects. Among these methods are electric harps, which are physical barriers that electrocute hornets pass through two wires powered by a current generator. Here we evaluated the selectiveness and risk of damage for local entomofauna of the electric harps in a study carried out over three years and four locations in Girona province (NE Catalonia, Spain). The electric harps showed a high selectiveness, with 90.5% of all insects trapped (3331 individuals) catalogued as Asian hornets, although this greatly varied over years and locations with values ranging from 29.9 to 94.3%. The risk of damage to electric harps for local entomofauna was very low in all surveyed areas and years. Native insects, excluding domestic honey bees, accounted for, as a mean, 1.2% of all insects trapped over the study period (range 0–2.4%). Our results suggest that electric harps might be a useful environmentally-friendly method aiming to reduce predation pressure of the Asian hornet at beehives.