Effects of artificial shortening of the photoperiod on honeybee (Apis mellifera) polyethism

The photoperiod was artificially shortened for free-flying honeybee colonies in May, June and July in order to simulate day-lengths of October, November and December. The effects on population development and on worker physiology were examined. There was no significant effect on numbers of brood cells or adult bees, or on the dry weight of the hypopharyngeal glands. The survival rates of workers did not increase significantly. On the other hand, the shortening of the photoperiod led to a winter-bee-like increase of the lipid and protein content of the fat body. However, the 'short-day' treatment was not enough to trigger the development of long-living winter bees.