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2014-12-12 - Colloque/Présentation - poster - Anglais - 1 page(s)

Declèves Sylvain, Michez Denis , Vanderplanck Maryse , "Asteraceae paradox for bumblebees" in Benelux Congress of Zoology, Liège, Belgique, 2014

  • Codes CREF : Chimie analytique (DI1314), Entomologie (DI3163), Ecologie chimique (DI312G), Ecologie (DI3123)
  • Unités de recherche UMONS : Zoologie (S869)
  • Instituts UMONS : Institut des Biosciences (Biosciences)

Abstract(s) :

(Anglais) Through pollen collection, bees act concurrently as effective pollinators and herbivores. Regardless of floral specialization, they display numerous adaptations as well as sensorial capabilities, which allow them to discriminate among plant species and to enhance floral rewards foraging. In response to excessive pollen harvesting, flowers developed complex defense systems through particular morphological and/or chemical traits. In particular, recent findings support that Asteraceae pollen possesses unfavourable or protective properties and suggests that bees need physiological adaptations to successfully utilize it. Although Asteraceae are ubiquitous in most terrestrial habitats and produce considerable amounts of pollen, this pollen plays only a marginal role in the diets of the pollen generalists by striking contrast to specialists. Despite numerous hypotheses, this paradox remains unsolved. To investigate the unfavourable pollen properties of the Asteraceae for generalist bees, chemical analyses of pollen and bumblebee rearing were performed on Cirsium-type pollen. The colonies performances were compared to those from other diets known to be suitable to the model Bombus terrestris (i.e. willow and clover pollen). Digestibility (i.e. quality of feces) as well as toxicity (i.e. alkaloids) and nutrient content (i.e. total amino acids) of Cirsium-type pollen were examined. Results revealed that unsuccessful exploitation of Asteraceae pollen by bumblebees is not necessarily related to amino acid or alkaloid contents. However incomplete digestion of pollen grains seems indicate difficulties in extracting nutrients from the pollen. Other properties are currently investigated to elucidate this Asteraceae paradox.