Octopamine modulates honey bee dance behavior

Abstract

Honey bees communicate the location and desirability of valuable forage sites to their nestmates through an elaborate, symbolic "dance language." The dance language is a uniquely complex communication system in invertebrates, and the neural mechanisms that generate dances are largely unknown. Here we show that treatments with controlled doses of the biogenic amine neuromodulator octopamine selectively increased the reporting of resource value in dances by forager bees. Oral and topical octopamine treatments modulated aspects of dances related to resource profitability in a dose-dependent manner. Dances for pollen and sucrose responded similarly to octopamine treatment, and these effects were eliminated by treatment with the octopamine antagonist mianserin. We propose that octopamine modulates the representation of floral rewards in dances by changing the processing of reward in the honey bee brain. Octopamine is known to modulate appetitive behavior in a range of solitary insects; the role of octopamine in dance provides an example of how neural substrates can be adapted for new behavioral innovations in the process of social evolution.

Fig. 1.

Effect of OA on honey bee waggle dances. (A) Schematic of round and waggle dances. In waggle dances, the duration of the waggle phase corresponds to the distance to a resource. The angle of the waggle phase of a dance relative to vertical corresponds to the angle between the food source and the sun on departure from the hive. A single waggle phase and return loop is one dance circuit. In round dances, the dancer runs in a tight loop reversing direction at the end of each circuit. (B–F) Effect of topical OA treatment on different elements of the waggle dance (Experiment 2). Bees were treated topically with one of four different doses of OA or dimethylformamide (DMF) as a control. More than 20 bees were analyzed per group. Bars present mean values ± SE. Superscripts refer to nonparametric statistical analyses. Columns marked by different superscripts differ at the 5% confidence level. (B) Dance likelihood: mean and S.E. calculated from arcsin transformed values; groups that differ statistically from DMF are marked by different superscripts (Mann–Whitney tests with Bonferroni correction). (C–F) Differences between treatment groups were tested with Kruskal–Wallis tests, and comparisons between specific groups were made with Dunn's post hoc tests.

Fig. 2.

Effect of OA and OA antagonist on round dances for sucrose (Experiment 3). Bees were treated topically with 2 μg of OA, 2 μg of mianserin, or both, in 1 μl of DMF. There were >30 bees per treatment group. Statistical analyses and notations are as in Fig. 1.

Fig. 3.

Effect of topical OA treatment on round dances for pollen (Experiment 4). The percentage of bees that danced at least once during the 1-h observation period is shown. The sample size is shown above bars; groups that differed from OA-treated at the 5% confidence interval (χ² test) are marked with an asterisk (∗).