Floral preferences of bumblebees across a range of European climates
BACKGROUND. Bumblebees are agriculturally important pollinators, but are currently declining in abundance in the UK and around the world, in part due to climate change (Soroye et al. 2020). Understanding these declines requires research on the biology and ecology of these species. Bumblebees are thought to be generalists, pollinating a variety of flower species. However, our preliminary observations conducted in Durham in summers 2020-22 indicate that different bumblebee species prefer different plants (see also Sikora et al. 2020). Bumblebees have been a preferred insect model for neuroethology and sensory neuroscience, and a wealth of earlier work has focussed on the importance of visual cues and nectar/pollen reward for foraging honeybees and bumblebees (Latty and Trueblood 2020). In contrast, the importance of floral smells is less well known, although some works report the essential role of flower volatiles in bumblebees’ floral choice (Galen and Kevan 1983; Suchet et al. 2011; Haber et al. 2019). This project will investigate olfactory preferences of commonly occurring bumblebees (e.g. Bombus terrestris, Bombus pascuorum and Bombus lapidarius) to naturally-occurring floral volatiles, and how these preferences are affected by climatic conditions and background plant communities in Norway (Kløfta), UK (Durham and Stirling), Germany (Würzburg), Italy (Milan) and Portugal (Braganca). We expect the plants that the bumblebees forage on to differ between these location, due to different climatic condition. We hypothesise that, despite the differences in plant species, the key components of floral bouquets will be very similar across test locations.
AIMS. 1) To identify plants that bumblebees forage on in the five countries, to establish plant preferences for bumblebee species; 2) Collect floral volatiles from the plants identified in Aim 1, as well as florals that bumblebees do not forage on, as controls; analyse these volatiles by GC/MS ; 3) Establish behavioural preferences of bumblebees in response to full floral bouquets and components of bouquets, fractions and synthetic components of that are specific for focal plant species.
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