Sarracenia carnivorous plants cannot serve as efficient biological control of the invasive hornet Vespa velutina nigrithorax in Europe

Vespavelutinanigrithorax, an invasive species, a direct result of increased trade and climate change, is spreading rapidly in Europe and endangering entomofauna in general and more alarmingly honeybee (Apismellifera) populations, and therefore their pollination services. All traps used now, to try to control this species, seem to be not efficient enough and non-selective. However, in the current context of massive disappearance of insects in general, it is urgent to find means of protection for the entomofauna. While no selective trapping is still occurring, we performed a pilot study to test a carnivorous plant as a potential biocontrol tool to trap V.velutina. In our study, we analyzed the hornet-capturing ability of two Sarracenia hybrids (S.juthatipsoper and S.evendine) on a 2-years period (2015 and 2016). Our results show that these plants trapped more dipterans than other taxa, and they do not attract many hornets. In such condition, both Sarracenia hybrids cannot therefore be used in a mass trapping system, because they are not selective, and too few hornets are trapped. To maximize captures of V.velutina while minimizing captures of non-target species, other systems need to be thus developed, as traps using hornet pheromone-based baiting.