FLORAL FRAGRANCES AND THEIR IMPORTANCE IN POLLINATION BY BUMBLEBEES

BERGQUIST, Pia
Göteborg University, Chemical Ecology, Department of Botany, Carl Skottsbergs Gata 22, S413 19 Göteborg, Sweden

What makes a bumblebee choose to visit and probe a particular flower? Foraging bumblebees preferentially choose to visit flowers that are rich in rewards, primarily nectar (Wetherwax, P B.:Oecologia 69, 567-70 (1986)). It is known that bumblebees use scents, e.g scentmarking of trails to their nest, and it could be expected that they use scents in other ways too. This study specifically investigates the importance of scents in pollination by bumblebees.

These studies are made with Bombus terrestris and several different bumblebee-visited flowers (e.g. Primula veris and Trifolium repens). The two main questions are:

1. What role do the scents play?
   This is studied in bioassays where bumblebees are presented with a two-way choice of flower models with and without scents.
2. What scents do the bumblebees use?
   Floral scents are collected with head-space adsorption and analysed for their components with GC-MS.

The strength of this study lies in combining bioassays with chemical analysis of floral scents.