The genetic architecture of fitness-relevant traits in natural populations is a topic that has remained almost untouched by quantitative genetics. Given the importance of parasitism for the host's fitness, we used QTL mapping to study the genetic architecture of traits relevant for host-parasite interactions in the trypanosome parasite, Crithidia bombi and its host, Bombus terrestris. The three...

For bumblebee colony survival, sugar responses are crucial as nectar is the main carbohydrate source and flower choice is likely determined by sugar composition. This study used a bioassay both with harnessed and with free-moving workers of the bumblebee Bombus terrestris to study the gustatory response to the 3 major plant sugars by both groups. In harnessed workers of B. terrestris, a concent...

We investigated labor-related plasticity in the circadian clock of the bumblebee Bombus terrestris. Bumblebee workers vary enormously in body size, and we found that size, division of labor, and diurnal rhythms in activity are correlated in B. terrestris colonies. Large workers typically perform foraging activities with strong diurnal rhythms and low activity at night, whereas small bees typica...

Our understanding of how floral visitors integrate visual and olfactory cues when seeking food, and how background complexity affects flower detection is limited. Here, we aimed to understand the use of visual and olfactory information for bumblebees (Bombus terrestris terrestris L.) when seeking flowers in a visually complex background. To explore this issue, we first evaluated the effect of f...

BACKGROUND The adaptive maintenance of flower color variation is frequently attributed to pollinators partly because they preferentially visit certain flower phenotypes. We tested whether Gentiana lutea-which shows a flower color variation (from orange to yellow) in the Cantabrian Mountains range (north of Spain)-is locally adapted to the pollinator community. METHODS We transplanted orange-f...

Bumblebees (Bombus spp.) have undergone a documented Europe-wide decline in recent years, mostly attributable to destruction of forage and nest sites caused by agricultural intensification. This study was set up to quantify species-specific nest-site preferences of observed UK species for various types of field and forest boundary habitat. In total, 1287 observations were made of seven common b...

In southern England, Linaria vulgaris (common yellow toadflax) suffers from high rates of nectar robbery by bumblebees. In a wild population of L. vulgaris we found that 96 % of open flowers were robbed. Five species of bumblebee were observed foraging on these flowers, although short-tongued species (Bombus lapidarius, B. lucorum and B. terrestris) robbed nectar whilst longer-tongued ones beha...