bee learning and communication

Bee learning and communication includes cognitive and sensory processes in all kinds of bees, that is the insects in the seven families making up the clade Anthophila. Some species have been studied more extensively than others, in particular ''Apis mellifera'', or European honey bee. Color learning has also been studied in bumblebees.

Honey bees are sensitive to odors (including pheromones), tastes, and colors, including ultraviolet. They can demonstrate capabilities such as color discrimination through classical and operant conditioning and retain this information for several days at least; they communicate the location and nature of sources of food; they adjust their foraging to the times at which food is available; they may even form cognitive maps of their surroundings. They also communicate with each other by means of a "waggle dance" and in other ways.

Learning

Honey bees are adept at associative learning, and many of the phenomena of operant and classical conditioning take the same form in honey bees as they do in the vertebrates. Efficient foraging requires such learning. For example, honey bees make few repeat visits to a plant if it provides little in the way of reward. A single forager will visit different flowers in the morning and, if there is sufficient reward in a particular kind of flower, she will make visits to that type of flower for most of the day, unless the plants stop producing nectar or weather conditions change.

Memory

A 2005 three-part study tested the working memory of honey bees, after learning to associate a certain pattern with a reward (delayed matching-to-sample). Bees were shown a pattern at the beginning of a tunnel, and then subjected to a series of variations: in the length of the tunnel (How long can bees retain the pattern in working memory?), in a choice between two patterns (matching and non-matching) placed at different distances (Can bees trained in the task continue to perform correctly when the matching pattern as well as a non-matching pattern are presented in the tunnel?); and a choice between two patterns (Can bees learn which of two sequentially encountered patterns in the tunnel is the pattern to be matched in the decision cylinder?). The researchers found that working memory in the honey bee is both robust and flexible. The experiments demonstrated that bees can choose between alternatives, determine if a stimulus is the same or different than one seen earlier, remember the earlier one for a short period, and generalize this performance to new pairs of stimuli. The bees retained information in working memory for about 5 seconds, and they might have been simultaneously learning a matching and a nonmatching task; further research was needed.

Color learning

Color learning in honeybees

A number of experiments have demonstrated color recognition, discrimination and memory in honey bees ''Apis mellifera''. Beginning in the early 1900s, scientists Karl von Frisch and later Randolf Menzel began asking questions about color vision and various aspects of color learning in bees.

Color discrimination

The Austrian zoologist Karl von Frisch began the exploration of color vision in honey bees when, in 1919, he asked whether or not bees have color vision. He performed an elegant experiment that showed not only that the bees could discriminate colors but that they demonstrated associative learning. He first trained his bees to feed from a small dish filled with a nectar-like sugar water. This dish was placed on a piece of blue colored cardboard so that the color was visible to the bees as they arrived at the dish and fed. Next, von Frisch placed identically sized pieces of cardboard in varying shades of grey, each with a dish, all around the blue piece.Frisch, K. von. 1956. Bees; their vision, chemical senses, and language. Ithaca, N.Y., Cornell University Press. Lacking color vision, the bees should visit one or more of the gray pieces as often as the blue piece, but he found the vast majority of the bees flew directly to the blue piece of cardboard on which they had previously obtained their reward. The bees largely ignored the gray pieces which had not been rewarded. Von Frisch repeated the experiment with other colors like violet and yellow and got the same results. Later other researchers used this experimental design to test the color vision of vertebrates.

Color learning rates and preferences

The German scientist Randolf Menzel continued the study of color vision in honey bees with more detailed tests. He was curious about whether bees would learn certain colors faster than others. He used lights of various color and intensity to project circles of light on a surface, a set-up like that used by von Frisch except that, by using light instead of cardboard, Menzel was able to easily change the intensity and color of the circles.

To test bees ability to distinguish between two different colors, Menzel placed a small dish containing sugar-water in one circle and a second empty dish some distance away on a differently colored circle. A single bee was placed equidistant between the two circles and allowed to choose between the dishes. The bees quickly learned to choose the color signaling the dish with the reward, and Menzel was able to measure how quickly the bees learned this task with various color differences.Menzel, R. and Backhaus, W. 1989. Color vision in honey bees: Phenomena and physiological mechanisms. In D. Stavenga and R. Hardie (eds): Facets of vision. Berlin-Heidelberg-New York: 281-297

Menzel's results showed that bees do not learn to discriminate between all color pairs equally well. Bees learned the fastest when violet light was rewarded, and the slowest when the light was green; the other colors fell somewhere in between. This evidence of inherent bias is evolutionarily reasonable, given that bees forage for differently-colored nectar-bearing flowers, many of which are to be found in green foliage which does not signal reward.

Color memory

After his work on color preferences, Menzel extended his experiments to study aspects of color learning and memory. He wanted to know how many trials bees need to reliably choose a previously rewarded color when they are presented with several alternatives, and how long they would remember the rewarded color.

Menzel did several experiments to answer these questions. First, he gave individual bees a single sugar reward on a colored background. He then kept these bees in small cages for several days without any further trials. After a few days, he presented each bee with an array of several dishes, each on a different colored background. One of the colors was the same as that used during the initial trial, and the others were novel, unrewarded colors. Remarkably, after a single trial and several days without exposure to the rewarded color, bees correctly chose to explore the color used in the first trial more than fifty-percent of the time.

Menzel then repeated this experiment with another group of bees, keeping all factors the same except that in the second round of testing he gave the bees three initial trials with the rewarded color instead of just one. When, after several days in confinement, the bees were presented with a choice of colors they almost always chose the color that was used on the first three trials.

This ability to retain information about color-linked rewards for several days after minimal exposure to the rewarded color demonstrates the remarkable facility with which bees learn and retain color information.

Timing in color learning

In still other experiments, Menzel explored the timing of bee color learning by testing whether bees register color before, during, or after receiving their sugar-water reward. For this purpose Menzel displayed the color beneath a rewarded dish at different stages of the honey bee feeding process: during approach, feeding and departure.

Menzel found that bees register color during both approach and feeding, and that they had to see the color for about a total of about 5 seconds, with best performance usually coming with about three seconds exposure during the approach and two seconds after landing and beginning to feed.Menzel, R. and Backhaus, W. 1991. Colour Vision in Insects. In P. Gouras (ed): Vision and Visual Dysfunction. The Perception of Colour. London: MacMillan Press, 262-288.

Color learning in bumblebees

An American specialist in bee cognition, Dr. Felicity Muth, has studied the mechanism behind the associative learning in bumblebees, specifically ''Bombus impatiens''. Bumblebees were shown to be able to learn multiple color-food associations and tended to continue to apply what they learned. In another study, Dr. Felicity Muth continued to learn more about these associations. Bumblebees initially preferred yellow anthers and blue corollas when foraging for pollen. After this initial test, they began associating floral color with pollen success. The bumblebees' association between pollen and features of the