Suppression of worker fertility in the honey bee (Apis mellifera) by treatment with X-rays

Breeding of the honey bee normally involves measurement of traits at the colony level. Nevertheless, there are traits that can be observed at the level of the individual worker. In this case, workers with interesting features are artificially induced to parthenogenetically produce offspring. In order to promote fertility in the worker bee of interest, it is useful to suppress the fertility of all other workers. In this study, our aim was to produce sterile bees by the application of ultra-hard X-rays. We irradiated capped brood of different ages with a dose of 20 Gy. This treatment suppressed fertility in all treated workers, while controls laid normal amounts of eggs. However, rare cases of fully developed ovaries occurred in workers when pupae were irradiated 0-4 days prior to emergence. In these bees, ovary development was retarded compared to controls. Hypopharyngeal glands degenerated more quickly in irradiated bees than in the controls, and mortality was heightened. Production of wax also was reduced. Radiosensibility of pupae dropped after approximately 110 h of age, egg and larval stages included. Given the rapid degeneration of hypopharyngeal glands in the irradiated bees, the usefulness of irradiated workers for breeding from single workers seems doubtful.