10.1. Introduction

When a honey bee forager discovers a profitable floral patch in the field it returns to the nest to share the collected resource with its nest mates. Either during or after unloading the food, the honey bee can perform a series of repetitive waggle movements on the wax comb (Fig. 21). The first person to analyse and to decode this form of honey bee communication was Karl von Frisch. He was awarded the Nobel Prize in Medicine and Physiology in 1973 for his contributions to behavioural sciences. More than six decades ago, Karl von Frisch began to train honey bees to forage at an artificial feeder by using sucrose syrup as reward (see von Frisch, 1967 for review; see also section 14). While the bees that arrived at the feeder fed from the liquid food he marked them with acrylic paint. This procedure allowed von Frisch to follow the behaviour of individual bees not only at the artificial feeder but also inside the nest. In-hive observations were possible because he had built a two-comb hive (see also section 9). In this way, he was able to observe and describe that the marked foraging bees returned to the hive, unloaded their crop and often performed a complex motor-coordinated pattern on the vertical wax combs. If von Frisch located the feeder 100 m or more away from the hive, the marked bees displayed a figure-of-eight shaped movement which he defined as the waggle dance (Schwänzeltanz in German). During the waggle dance, the bee releases intense vibrations and moves its body laterally as it runs straight forward on the comb (the waggle-run phase). The duration of each run during the waggle phase conveys information about the distance of the discovered resource whilst the orientation of the dancer's body relative to gravity during the waggle runs provides information on the direction of the goal (von Frisch, 1967). This complex motor pattern (see Fig. 21A) takes place not only when bees discover a profitable nectar source, but also when other resources such as pollen or water (von Frisch, 1967) or even potential nest sites (Lindauer, 1955) are found. If, on the other hand, the goal discovered is close to the nest, the display becomes a succession of running circuits in which the bee suddenly changes its direction after completing each round. This dance display, which indicates resources at a short distance, is known as the round dance (von Frisch, 1967).

Fig. 21A. The scheme represents the trajectory of a typical waggle dance, which encodes a far-distance goal. Two successive waggle runs are separated by round walks in which no waggle movements are made (the circle phase). The duration of the waggle runs correlates with the distance of the goal (food source or nest site) and the gravity-axis correlates with the orientation of the goal. The length of the circle phase has a negative correlation with the profitability of the food source. B. A photograph and C a thermogram of a successful forager (D) dancing on the wax comb while a group of nest mates (F) follow it. Whiter body parts in C indicate higher body temperatures. Note that the highest temperatures correspond to the dancer's thorax and head and to the different thoracic temperatures of the followers around the dancer.

1293PN revised Fig 21