DIURNAL CHANGES IN THE ACCURACY OF THE HONEYBEE FORAGING RHYTHM

Abstract

The ability of honeybees to time foraging visits to an artificial nectar source was analyzed with respect to the time of day of food source presentation. A consistent regimen of orientation and training to the food source, which was available only during a specific one-hour period of the day for each particular experiment, allowed quantitative comparisons to be made among groups of bees trained at different feeding times. Bees trained early in the day showed the most precise time-keeping ability whereas those trained to midday or late afternoon food sources were signif icantly less accurate. In all of the experiments, the bees anticipated the onset of the training period, but the duration ofthe anticipatory component ofthe response was dependent upon the training time. Similarly, other parameters (coefficients of skew ness and kurtosis and the shut-down in the number of arrivals immediately after the end of the training time) describing the distribution of foraging flights in time varied according to times in the diurnal cycle when the food source was offered. These results suggest that honeybees more efficiently exploit a daily floral nectar source if it is available early in the morning than if it is offered late in the day. Possible mechanisms underlying the observed differences in temporal orientation are discussed.