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2 Communication 3 External Link |
Learning
Learning is essential for efficient foraging. Bees are unlikely to make many repeat visits if a plant provides little in the way of reward. A single bee will visit differet flowers in the morning and, if there is sufficient attraction and 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 reward or weather conditions change. Bees are quite adept at associative learning, and many of the standard phenomena of conditioning take the same form in bees as they do in the vertebrates that are the more usual subjects of such experiments.
There are two main hypotheses to explain how foragers recruit other workers — the "waggle dance" or "dance language" theory and the "odor plume" theory. The dance language theory is far more widely accepted.
In 1947, Karl von Frisch correlated the runs and turns of the dance to the distance and direction of the food source from the hive. The orientation of the dance correlates to the relative position of the sun. There is no evidence that this form of communication depends on individual learning.
Von Frisch performed several experiments to validate his theory. He was awarded the Nobel Prize in Physiology or Medicine in 1973 for his discoveries.
The primary lines of evidence used by the odor plume advocates are 1) clinical experiments with odorless sugar sources which show that worker bees are unable to recruit to those sources and 2) logical difficulties of a small-scale dance (a few centimeters across) giving directions that precise enough to hold the other bees on course during a flight that could be several kilometers long. Misreading by even a few degrees would lead the bee off course by hundreds of meters at the far end.
Critics of the odor plume theory counter-argue that most natural nectar sources are relatively large - orchards or entire fields. Precision may not be necessary or even desirable. They have also challenged the reproducability of the odorless source experiment.
Von Frisch himself is said to have repudiated his "dance theory" later in life.
The academic debate between these two theories is extremely polarized and often hostile. Note: Essentially all the research on the two competing hypotheses of communication has been restricted to honeybees. Other bees may use other methods altogether.
Adrian Wenner, a modern bee researcher, is the chief proponent of the odor plume theory (anti-dance).
Communication
Bees communicate their floral findings to order to recruit other worker bees of the hive to forage in the same area. The factors that determine recruiting success are not completely known but probably include evaluations of the quality of nectar and/or pollen brought in.Dance language
It has long been known that honeybees perform a dance on their return to the hive. The nectar-laden bee dances on the comb in a circular pattern, occasionally crossing the circle in a zig-zag or waggle pattern. Aristotle in 330 B.C. described this behaviour in his Historia Animalium. It was thought to attract the attention of other bees.Odor plume
Proponents of the odor plume theory argue that the dance alone is insufficient to give other bees guidance to the nectar source. They argue that bees instead are primarily recruited by odor. The purpose of the dance is to attract attention to the returning worker bee so she can share the odor of the nectar with other workers who will then follow the odor trail to the source.External Link
Paper by Adrian Wenner: http://www.beesource.com/pov/wenner/jib2002.htm