The impacts of an invasive alien plant and its removal on native bees

Impacts de l'introduction puis de l'élimination d'une plante invasive étrangère sur les abeilles indigènes

Caroline Marijke Nienhuis , Anke Christiane Dietzsch , Jane Catherine Stout

Although the alien Impatiens glandulifera successfully invades riparian habitats and is visited by native insects, knowledge of its impact on native bees is limited. We assessed pollinator abundance in field sites where I. glandulifera was absent, present or had been experimentally removed. We measured insect visitation to flowers of potted native plants and to I. glandulifera. Bombus spp. comprised the highest proportion of visitors in invaded sites, whereas solitary bees made up the highest proportion in sites where I. glandulifera was removed. More bees, especially medium- and long-tongued Bombus spp. (B. pascuorum and B. hortorum), foraged on I. glandulifera than the native plant species (possibly because the alien was more abundant). We detected no impact of invasion on standardised pollinator abundance, B. pascuorum abundance, nor functional insect diversity, which may be due to variable climatic conditions. We suggest that future studies focus on impacts on rare or specialised pollinator taxa.

Mots clés: Bombus; Impatiens glandulifera; nectar secretion rate; nectar sugar concentration; Syrphidae<br>---<br>Bombus; plante invasive; plante introduite; secrétion nectarifère; concentration en sucres; nectar; pollinisateur; diversité écologique; abondance écologique

Domaines: Zoologie des invertébrés; Biodiversité; Ecologie, Environnement; Science des productions animales

Caroline Marijke Nienhuis, Anke Christiane Dietzsch, Jane Catherine Stout. The impacts of an invasive alien plant and its removal on native bees. Apidologie, 2009, 40 (4), ⟨10.1051/apido/2009005⟩. ⟨hal-00891979⟩