La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Critical resource levels of pollen for the declining bee Andrena hattorfiana (Hymenoptera, Andrenidae)
Auteurs :	Magnus Larsson, Auteur ; Markus Franzen, Auteur
Type de document :	Article
Dans :	Biological Conservation (134(3) JAN 2007)
Article en page(s) :	405-414
Langues:	Anglais
Résumé :	The native bee fauna provides an important ecosystem function, but a large proportion of this fauna in Europe is threatened as a result of habitat loss and fragmentation. The solitary bee Andrena hattorfiana is specialised on collecting pollen from the plant-family Dipsacaceae. In northern Europe the major pollen resource is the insect-pollinated herb Knautia arvensis. We quantified the available K. arvensis resource, measured habitat characteristics and performed a flower-visitor survey in 57 well-defined K. arvensis populations in southern Sweden. There was a strong relationship between bee and plant population sizes. In populations with A. hattorfiana present (N=26), the female bees utilised on average 39% (12-80%) of the total available pollen resource. The nest architecture and nesting biology of A. hattorfiana is described for the first time. By excavating nests, we found that the provisioning for one average bee nest (containing 6 cells) required ca. 72 inflorescences or

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