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

Vanderplanck Maryse , Glauser Gaëtan, Michez Denis , Praz C., "Aconitum and Bombus interactions: is floral rewards chemistry driving pollen-mixing behaviour in generalist bumblebees?" in Benelux Congress of Zoology, Liège, Belgique, 2014

  • Codes CREF : Chimie analytique (DI1314), Entomologie (DI3163), Ecologie chimique (DI312G), Ecologie (DI3123), Toxicologie [toxines] (DI3236)
  • Unités de recherche UMONS : Zoologie (S869)
  • Instituts UMONS : Institut des Biosciences (Biosciences)

Abstract(s) :

(Anglais) Plants synthesise an array of chemicals to defend themselves against herbivorous insects. Some of these defense compounds also occur in nectar and pollen, which constitute resources for pollinators. Such floral chemicals may be beneficial or detrimental to bees: they may protect them against disease and pathogens but also cause toxicity. How these toxins affect pollinator behavior, is not fully understood. Monkshoods (i.e. Aconitum species) are typical ‘bee-pollinated’ plants with large inflorescences and a specific floral morphology that makes their nectar accessible only for long-tongued visitors such as bumblebees. All the investigated species of Aconitum contain aconitine-like alkaloids, which are neurotoxic and for insects. Aconitum pollen contains particularly large concentrations of alkaloids compared to the leaves or the nectar. Pollen alkaloids may protect the flower from herbivores, or deter generalist pollen-collecting bumblebees, thus favoring nectar- visits over pollen-visits. A recent study suggested that pollen mixing in generalist bees may be considered as a possible strategy to exploit flowers with unfavorable pollen. To elucidate to what degree generalist bumblebees mix pollen in Aconitum- Bombus interaction system, pollen loads from two generalist species (Bombus hortorum and B. wurflenii) were collected in several sites with different Aconitum species and analyzed microscopically. In addition, chemical analyses were conducted on pure pollen and nectar of the Aconitum species, pollen loads from the two generalist bumblebees and from one Aconitum-specialist bumblebee (B. gersteackeri), as well as tissues of the three bumblebee species. Comparison between the different data allowed us to investigate potential alkaloid sequestration in bumblebees as well as potential dilution mechanisms of Aconitum pollen that could lead to alkaloid concentrations too low to affect generalist survival.