Search

À l’occasion du nouveau rapport de l’IPBES sur l’état de la biodiversité mondiale prévu pour mai 2019, la FRB donne chaque mois la parole à des scientifiques qui travaillent sur les menaces qui pèsent sur la biodiversité, mais aussi sur les solutions pour y remédier. Juristes, économistes, biologistes de la conservation sont autant de chercheurs qui offriront chacun un éclairage précis sur l’état et le devenir des espèces et de leurs écosystèmes. Le premier thème abordé est celui des espèces envahissantes, 4e cause de perte de biodiversité dans le monde.

International audience; In social insects, the activity rhythm of foragers and their action range determinate the activity of the colony. In vespids, which are mostly predators, the foraging range of workers determines their maximum predation pressure round the nest. One of these species, Vespa velutina, a recently invasive species introduced into Europe, exerts a strong predation on honeybees at the hive. Therefore, the definition of its activity rhythm and spatial range of predation is of primary importance. Using radio frequency identification tags (RFID), two experiments were carried out to (a) determine their return ability (called homing) in releasing 318 individuals at different distance from their colony and (b) monitor their foraging activity rhythm and the duration of their flights based on 71 individuals followed 24 hr/24 during 2 months. The homing ability of V. velutina was evaluated to be up to 5,000 m and was not affected by the cardinal orientation of release point. The lag time to return to the nest increased with the distance of release. Most of the flight activity took place between 07:00 a.m. and 08:00 p.m., hornets doing principally short flights of less than an hour. Foraging range was thus estimated ca. 1,000 m around the nest. This study of V. velutina assisted by RFID tags provides for the first time a baseline for its potential foraging distance that increase our knowledge of this species to (a) refine more accurately models for risk assessment and (b) define security perimeter for early detection of predation on invasion front.

International audience; Vespa velutina is an invasive species that was observed for the first time in France and Europe in 2004, which rapidly threatened domestic honeybees with active predation. For the first time in this study, we analyzed the distribution of V. velutina nests at a local scale to understand the pattern of nesting, and in 8 years of monitoring, a total of 528 nests were surveyed. With the exception of 2 years, the nests of V. velutina were randomly distributed within the monitored area, which suggested that intraspecific competition for nesting sites and/or food was unlikely. When the data for all years were combined, an aggregated distribution of nests at the seafront in the vicinity of the oyster farm and sportfishing activities was observed. This distribution suggested that seafood, attractive to vespids, might provide a valuable alternative food source that favored colony development. We also tested the effect of spring queen trapping of V. velutina on the distribution of nests in 2014, which was the year with the greatest number of colonies within the area; the position of the traps did not influence the distribution of the nests. For the first time, this study showed that (i) intraspecific competition was unlikely to be a mechanism for population regulation, (ii) some areas were more likely favored for hornet nests, and (iii) spring queen wasp trapping was inefficient as a method to limit the distribution of the V. velutina population.

International audience; The Asian Yellow-legged Hornet can devastate honeybee colonies, and its arrival in Europe has been the cause of great concern among beekeepers. The species is now common in parts of France and Spain, and with recent records in the UK, it appears to be on the brink of colonising our country. Karine Monceau and Denis Thiéry describe the impact that the hornet has had in its introduced range, and outline what, if anything, can be done to halt the invasion.

National audience

International audience; Vespa velutina is an invasive honeybee predator introduced more than a decade ago in southwest France, followed by an impressive colonization of several areas within mainland Europe (France, Spain, Portugal, Italy, Germany, Belgium) and overseas (UK, Mallorca). The purpose of this short review is to give an overview of the basic historic of this biological invasion, to expose the current situation and to propose perspectives based on the French experience.