New developments involving colors that bees are able to recognize have been discovered in new research at the University of Nevada, Reno. Postdoctoral Researcher Felicity Muth and Assistant Professor Anne Leonard of the College of Science have discovered that bees can learn colors based on pollen rewards and thus remember long-term which flowers have pollen and nectar.
Bees are model organisms for the study of learning and memory, yet nearly all such research to date has used a single reward - nectar, according to Muth. Her research found that many bees collect both nectar (carbohydrates) and pollen (protein) on a single foraging bout, sometimes from different plant species.
Muth said their experiment centered on the question, "If a bee collects nectar from one type of flower and then collects pollen from another type of flower, can she remember which flower type had which reward?"
To answer this question, Muth, Leonard and University of Arizona Professor, Daniel R. Papaj designed an experiment that involved bees foraging on artificial flowers that consisted of yellow corollas that had nectar but no pollen, and blue corollas which had pollen but no nectar. They let an individual bee fly around an experimental arena, collect the nectar and pollen, and return to her colony to remove the pollen and regurgitate the nectar into honeypots.
"After a few times of going between the foraging array and colony, it seemed like bees had learned where to go to collect nectar and where to go to collect pollen," Muth said. "It was easy to tell whether the bee was trying to collect nectar or pollen from a given flower because bees collected pollen from the artificial anthers (the part of a stamen that contains the pollen) of the flowers and nectar from a well at the base of the anther."
To further test if bees learned which flowers to go to, Muth displayed four artificial flowers that did not have any nectar or pollen in them. Two of the flowers were the ones that were previously encountered and the other two were new orange and purple flowers. In this test, they discovered that bees actually remember long-term which flowers have pollen and nectar.
"I found that if a bee had been trained to find pollen on yellow flowers and nectar on blue, then she searched for a pollen on the anthers of the yellow flowers and probed for nectar in the nectar wells of the blue flowers," Muth said.
Through this experiment, it was also discovered that pollen-foraging bees differentiate colors. Orange and yellow are similar in shade as well as purple and blue. During the experiment, the team observed that the bee had learned to search for pollen and nectar in the flowers that were colored most similarly with yellow and blue.
"After they had learned those associations, we further found that they would generalize them to new flowers that they had not previously experienced, but which were a similar color," Leonard said. "So, in essence, bees form expectations about what kind of reward a flower will offer based on its color."
The project was funded with $465,000 from Leonard's National Science Foundation grant.
Visit http://rsbl.royalsocietypublishing.org/content/11/9/20150628 for more detailed information regarding the experiments performed by Muth, Leonard and Papaj.