Indigenous strains of Beauveria and Metharizium as potential biological control agents against the invasive hornet Vespa velutina

Alien species often miss parasites in their invaded area, and this is the case in Vespa velutina. This invasive hornet predator of bees was accidentally introduced in Europe from East China in 2004. The control of this species is still problematic. Indeed to destroy nests, applicators currently use large spectrum insecticides, which is too costly or dangerous to applicators and also to the environment, affecting non-targeted arthropods (one period). Studying the potential interest of biological control methods may help to propose alternatives in V. velutina control. We present here the bioassays in which we assessed the potential control efficiency of different indigenous French isolates of entomopathogenic fungi. We inoculated adults V. velutina by different ways: being directly, by walking on a contaminated surface, in the food, or by inter-individual transfers. We tested differences between the isolates and the application methods using two parameters mortality and LT50. The direct inoculation method was the most efficient modality, then the contact, transfer and food. Considering all contamination methods, there was no difference on susceptibility or mortality among different isolates. Still the LT50 was quite short in all isolates (average 5.8 ± 0.44d), and their virulence was quite high: we conclude that there is high potential in using such entomopathogens as a biological control agent against V. velutina.Fil: Poidatz, J.. Institut National de la Recherche Agronomique; FranciaFil: López Plantey, Rodrigo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Thiéry, D.. Institut National de la Recherche Agronomique; Franci

Searching for nests of the invasive Asian hornet (Vespa velutina) using radio-telemetry

This is the final version of the article. Available from the publisher via the DOI in this recordAsian hornets (Vespa velutina) are voracious predators of bees, and are the latest emerging threat to managed and wild pollinator populations in Europe. To prevent establishment or reduce the rate of spread of V. velutina, early detection and destruction of nests is considered the only option. Detection is difficult as their nests are well hidden and flying hornets are difficult to follow over long distances. We address this challenge by tracking individual V. velutina workers flying back to their nests using radio telemetry for the first time, finding five previously undiscovered nests, up to 1.33 km from hornet release points. Hornets can fly with 0.28 g tags if the tag:hornet ratio is less than 0.8. This method offers a step-change in options to tackle the spread of this invader, providing an efficient means of finding V. velutina nests in complex environments to manage this emerging threat to pollinators.We thank Olivier Bonnard for discussions, sourcing materials, and advice on locating foraging V. velutina workers at INRA Bordeaux-Aquitaine. We also thank members of Jersey Beekeeping Association for their assistance in catching V. velutina workers in Jersey. The work was funded by a Defra research project grant (PH0532), with additional support by the States of Jersey Department of Environment and generous philanthropic donations by the South West Beekeeping Associations’ Forum (SWBKF), Somerset Beekeeping Association, Dorset Beekeeping Association, Cornwall Beekeeping Association, West Cornwall Beekeeping Association, Devon Beekeeping Association, Bournemouth & South Dorset Beekeeping Association, and B.J. Sherriff. We are grateful to INRA Bordeaux-Aquitaine, States of Jersey Department of Environment, and Durrell Wildlife Park for their welcome and permission to use facilities at their institutions