ETH Zürich, Institut für Terrestrische Ökologie, Grabenstrasse 3, CH-8952 Schlieren (Zürich), Switzerland.
Correlates of reproductive success among field colonies of Bombus lucorum: the importance of growth and parasites
Version of Record online: 14 MAR 2008
Volume 17, Issue 4, pages 343–353, November 1992
How to Cite
MÜLLER, C. B. and SCHMID-HEMPEL, P. (1992), Correlates of reproductive success among field colonies of Bombus lucorum: the importance of growth and parasites. Ecological Entomology, 17: 343–353. doi: 10.1111/j.1365-2311.1992.tb01068.x
- Issue online: 14 MAR 2008
- Version of Record online: 14 MAR 2008
- Accepted 28 May 1992
- Bumble bees;
- life history;
- reproductive performance
- 1In natural populations, colonies of bumble bees vary in many important life history traits, such as colony size and age at maturity, or the number and sex of reproductives produced. We investigated how the presence of parasites in field populations of the bumble bee Bombus lucorum L. relates to variation in life history traits and reproductive performance. A total of thirty-six colonies was placed in accessible nest sites in the field and monitored at regular intervals throughout a season.
- 2Among the life history correlates, early nest foundation was strongly associated with large maximum colony size, old age and large size at maturity, and this in turn with successful production of males and queens, as well as with the number of sexuals produced. Overall, reproductive success was highly skewed with only five colonies producing all the queens. Sixteen colonies failed to reproduce altogether.
- 3The social parasite Psithyrus was abundant early in the Bombus colony cycle and preferentially invaded host nests with many first brood workers and thus disproportionately large size, i.e. those colonies that would otherwise be more likely to reproduce or produce (daughter) queens rather than males. To prevent nest loss, Psithyrus had to be removed soon after invasion. Therefore, the effects reported here can only be crude estimates.
- 4Parasitoid conopid flies are likely to cause heavy worker mortality when sexuals are reared by the colonies. Their inferred effect was a reduction in biomass that could be invested in sexuals as well as a shift in the sex ratio at the population level resulting from failure to produce queens. We suggest to group the inferred correlates into ‘early events’ surrounding colony initiation and social parasitism, and ‘late events’ surrounding attained colony size in summer and parasitism by conopid flies. Our evidence thus provides a heuristic approach to understand the factors that affect reproductive success of Bombus colonies.