Bees use waggle dance to communicate with their nest mates the flight distance and direction to foraging sites. Now, a research team led by Axel Brockmann at the National Centre for Biological Sciences (NCBS), Bengaluru, has studied how bees use complex memory to generate dance duration to communicate a change in foraging distance.
Bees are known to waggle dance near the entrance of the hives. The duration of the waggle run of a dancing bee correlates with the distance between the food site and the hive. For instance, as the distance to the foraging site increases, the duration of waggle increases too.
The team used the honey bee species Apis mellifera for the study. “Most of the research on the brain and behaviour of bees around the world is done with the help of A. mellifera and therefore we could put our results into the context of all the research done previously,” says Dr. Brockmann.
Memory formation
To understand in detail memory formation in bees for waggle dance, the researchers trained a group of honey bees to forage food kept 300 metres away from the hive. When the food source was shifted to 400 metres, most of the bees took multiple trips to the new foraging site to update their dance. Till such time the bees formed the new memory, they displayed an intermediate dance duration indicating distances in between the new and old foraging locations.
“One must assume that the bees, when arriving at the new feeder site, know the distance between the feeder and the hive. If not, they will not be able to find the way back. The occurrence of intermediate dance durations indicates that the bees use memory of both distances when they update the dance information,” says Dr. Brockmann.
It was also noticed that the memory processes of bees responded differently depending on whether the foraging distance was extended or shortened from the original distance of 300 metres. When the feeder was shifted from the original distance of 300 metres to 200 metres and back to 300 metres, the bees were able to update the feeder distance following each shift and communicate the distance correctly through waggle dance.
In contrast, when the feeder was shifted from the original distance (300 metres) to 400 metres the bees were able to communicate the longer foraging distance. But when brought back to the original distance of 300 metres, it continued to exhibit the waggle duration for 400m.
“The foraging site at 400 metres was new to the bees unlike the one at 200 metres which the bees visited earlier during the training process. Therefore, when the feeder was first shifted to a novel site [400 metres] and then back to the original site [300 metres], honey bees did not update the waggle duration after the second shift. This is likely due to new memory interfering with the recall of an older one,” says Arumoy Chatterjee, a PhD student at the institute. He is the first author of the paper published in Journal of Experimental Biology.
“Previously, there was no easy way to dissociate the waggle dance activity of honey bee foragers from their foraging activity. Our experiments now provide us with the means to dissociate them, an essential first step towards understanding the mechanisms underlying the conversion of flight information to waggle dance information”, adds co-author Ebi George, another PhD student at the institute.
