Sperm competition and last-male precedence in the honeybee

Five microsatellite loci were used to determine paternities in six Apis mellifera colonies headed by naturally mated queens. The last inseminating males were identified by collecting and genotyping the mating sign left in the genital tract of each queen. Significant differences in paternity frequencies were observed between males, but the proportion of worker and queen offspring sired by the last inseminating drone did not differ significantly from those of other drones. Each male kept his rank of precedence for the different cohorts, although the variance in subfamily proportions decreased over time, most notably in the colony displaying the lowest level of polyandry. These results suggest that, if sperm competition exists in the honeybee, it does not significantly increase the fitness of the last inseminating drone. The spermatozoa of the different inseminating drones are not totally mixed before they reach the spermatheca, in particular when only few males mate with the queen. The weak difference in the subfamily proportions observed between queen and worker samples confirms that nepotistic interactions are rare. (C) 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.