Simultaneous queen raising and egg laying by workers in Africanized honeybee colonies (Apis mellifera L) in Costa RicaJ. van der Bloma, W.J. Bootb and H.H.W. Velthuisa
a Laboratory of Comparative Physiology, Utrecht University, PO Box 80086, 3508 TB Utrecht, The Netherlands
b Dept of Entomology, Wageningen Agricultural University, PO Box 8031, 6700 EH Wageningen, The Netherlands
Abstract - Twenty small queenless colonies of mixed European-Africanized origin were set up to study the development of emergency queen cells, ovarian activation and egg laying by workers. In 2 of the colonies, laying workers were present in large numbers before the queens matured from the emergency queen cells. A low number of worker-laid eggs was found in 7 colonies. In the other colonies, the level of ovarian activation of the workers at the end of the queenless period was very variable. We conclude that the occurrence of egg-laying workers in colonies that still contain young brood is not a rare phenomenon in Africanized bees. No worker-laid eggs were found in any of the colonies once a queen had emerged. There was no correlation between the level of ovarian activation (ie the size of the eggs inside the ovaries) and either the number of queen cells raised or the number of empty queen cups constructed. The average number of ovarioles per worker per colony varied between 3.79 and 8.33 per ovary. Since there was no correlation between the number of ovarioles and the level of ovarian activation (either within or between colonies), we conclude that these are independent traits in a mixed population.
Key words: Africanized honeybees / worker reproduction / population biology / ovarian activation / ovarioles