6.4. Inability to requeen

In cases where supersedures failed, some authors focused their experiments on the ability of orphan colonies to rear new queens. Before aerial application of fenthion, an organophosphate insecticide, Nunamaker et al. (1984) placed orphan colonies in a pasture due to be treated. After treatment, they noticed that some new queens emerged at a later date, compared with control colonies, but neither egg-laying queens nor eggs were found in the exposed colonies.

When Stoner et al. (1985) fed nurse colonies for queen rearing purposes with sugar syrup contaminated at 5 mg/kg of acephate, an organophosphate insecticide, for several weeks, most of the queen cells aborted. To observe the effects of 4 insecticides (fenoxycarb, diflubenzuron, tebufenozide, azadirachtin), known as IGR insecticides, on newly emerged queens, Thompson et al. (2005), transferred queen cells in nuclei containing about 1000 worker bees and supplied them with contaminated fondant. In the fenoxycarb treated group, the emerged queens showed virgin queen characteristics but none of them successfully mated or laid eggs. These authors were also interested in the effects of the molecules on the drones. They concluded that the number of mature drones was reduced in the diflubenzuron treated colonies and even absent from some fenoxycarb ones.