Long foraging distances impose high costs on offspring production in solitary bees
Article first published online: 5 MAR 2010
© 2010 The Authors. Journal compilation © 2010 British Ecological Society
Journal of Animal Ecology
Volume 79, Issue 3, pages 674–681, May 2010
How to Cite
Zurbuchen, A., Cheesman, S., Klaiber, J., Müller, A., Hein, S. and Dorn, S. (2010), Long foraging distances impose high costs on offspring production in solitary bees. Journal of Animal Ecology, 79: 674–681. doi: 10.1111/j.1365-2656.2010.01675.x
- Issue published online: 22 MAR 2010
- Article first published online: 5 MAR 2010
- Received 10 November 2009; accepted 1 February 2010 Handling Editor: Simon Leather
- bee conservation;
- fitness cost;
- habitat fragmentation;
- megachilid bee;
1. Solitary bees are central place foragers returning to their nests several times a day with pollen and nectar to provision their brood cells. They are especially susceptible to landscape changes that lead to an increased spatial separation of suitable nesting sites and flower rich host plant stands. While knowledge of bee foraging ranges is currently growing, quantitative data on the costs of foraging flights are very scarce, although such data are crucial to understand bee population dynamics.
2. In this study, the impact of increased foraging distance on the duration of foraging bouts and on the number of brood cells provisioned per time unit was experimentally quantified in the two pollen specialist solitary bee species Hoplitis adunca and Chelostoma rapunculi. Females nesting at different sites foraged under the same environmental conditions on a single large and movable flowering host plant patch in an otherwise host plant free landscape.
3. The number of brood cells provisioned per time unit by H. adunca was found to decrease by 23%, 31% and 26% with an increase in the foraging distance by 150, 200 and 300 m, respectively. The number of brood cells provisioned by C. rapunculi decreased by 46% and 36% with an increase in the foraging distance by 500 and 600 m, respectively.
4. Contrary to expectation, a widely scattered arrangement of host plants did not result in longer mean duration of a foraging bout in H. adunca compared to a highly aggregated arrangement, which might be due to a reduced flight directionality combined with a high rate of revisitation of already depleted flowers in the aggregated plant arrangement or by a stronger competition and disturbance by other flower visitors.
5. The results of this study clearly indicate that a close neighbourhood of suitable nesting and foraging habitats is crucial for population persistence and thus conservation of endangered solitary bee species.