Effects of fructose-1,6-diphosphate administration on learning efficiency and time sense of the honey bee, Apis mellifica carnica

In discrimination experiments honey bees had to decide between two glass dishes, one placed on a black cross, the other 40 cm away on a black square. In spontaneous selections the bees in 70% of all cases chose the black cross. The bees were then trained to search back and forth between the cross and the square until after 5 min sugar-water was given on the black square. Over a total of 5 learning trials, during which multiple decisions had been made by the searching insects, 96% of all choices were in favour of the black square. If 80 mM fructose-1,6-diphosphate (F-1,6-P2) in 1 M glucose had been ingested by the bees 30 min before the first spontaneous choice, learning was facilitated with 83% deciding in favour of the black square at the first trial compared with 46% of the controls (which had been fed on 1 M glucose only). In both groups of bees the same number of flight approches was made to the cross or square as made by the bees searching for 5 min before the reward was given. Thus no change in general activity or harvesting motivation appears to be induced by F-1,6-P2. When F-1,6-P2 had been given at the end of a successful learning series the bees favoured the black square for up to 3 days. In contrast to the controls no new incentive needed to be given during this period. Ingestion of other metabolites proved either ineffective, as in the case of fructose-6-phosphate or 5'-adenosine monophosphate, or, as observed after feeding citrate plus 3-phosphoglycerate, even reduced the performance. To test the effect of F-1,6P2 on the same time sense (circadian rhythm), bees were trained on three successive days to visit a feeding place at a specific time of day. The control bees which ingested only glucose on the evening of the 3rd day returned at their entrained 24-h interval on the 4th day. In contrast, the maximum frequency of appearance of bees fed on F-1,6-P2 was advanced by one hour, with minor appearance peaks at earlier hours of the day.