Effectiveness of electric harps in reducing Vespa velutina predation pressure and consequences for honey bee colony development

Abstract

BACKGROUND: Vespa velutinahas become a species of concern in invaded regions of Europe and Asia, due to its impacts onbiodiversity, apiculture and society. This hornet, a ferocious hunter of pollinating insects, poses a serious threat to biodiversityand pollination services. Despite ongoing efforts, its extermination in continental Europe is hampered by a lack of effective con-trol methods, thus effective mitigation measures are primary concerns. The aims of this work were: (i) to study the effects of V. velutina predating on honey bee colonies, and (ii) to assess the effectiveness of electric harps in reducing hunting pressureand predation. We assessed the predation pressure and compared honey bee colony performance, body weight of workers, andwinter survivorship for protectedversusunprotected colonies in 36 experimental hives across three apiaries. RESULTS: Electric harps protected honey bees by reducing predation pressure and therefore mitigating foraging paralysis. Consequently, foraging activity, pollen income, brood production and worker body weight were higher in protected colonies whichin turn showed greater winter survivorship than those that were unprotected, especially at sites with intermediate to highlevels of predation. CONCLUSION: The predation of V. velutina affects foraging activity, breeding, body weight and colony survivorship of Apis mellifera. Electric harps contribute significantly to mitigate the impact of this invasive hornet on apiaries; however, they should bedeployed in tandem with additional measures to preserve honey bee colony stocks, such as facilitating access to food sourcesfor colonies during the periods of highest predation pressure.