Octopamine and tyramine influence the behavioral profile of locomotor activity in the honey bee (Apis mellifera)

Abstract

The biogenic amines octopamine and tyramine are believed to play a number of important roles in the behavior of invertebrates including the regulation of motor function. To investigate the role of octopamine and tyramine in locomotor behavior in honey bees, subjects were injected with a range of concentrations of octopamine, tyramine, mianserin or yohimbine. Continuous observation of freely moving worker bees was used to examine the effects of these treatments on the amount of time honey bees spent engaged in different locomotor behaviors such as walking, grooming, fanning and flying. All treatments produced significant shifts in behavior. Decreases in time spent walking and increases in grooming or stopped behavior were observed for every drug. However, the pattern of the shift depended on drug, time after injection and concentration. Flying behavior was differentially affected with increases in flying seen in octopamine treated bees, whereas those receiving tyramine showed a decrease in flying. Taken together, these data provide evidence that octopamine and tyramine modulate motor function in the honey bee perhaps via interaction with central pattern generators or through effects on sensory perception.

Figure 1

The effects of octopamine on honey bee behavioral profiles. The percent of time subjects spent engaged in each behavior is shown for treatment with each concentration of octopamine. Treatment consisted of injection with 2 μl of 5 × 10⁻², 5 × 10⁻³, 5 × 10⁻⁴, 5 × 10⁻⁵ M octopamine or buffer alone. Data represent the average of 11 to 13 independent observations and error bars indicate the SEM. The interval of time post injection is indicated. A) Behavioral profiles are significantly different among bees given different treatments at the 35–40 and the 40–45 min intervals. B) Time spent flying versus time after injection for bees treated with octopamine. This is the same data included in the behavioral profiles in A shown on a separate graph to aid comparison. For intervals in which significant differences in behavioral profiles occurred, asterisks indicate significant differences in time spent in that behavior by bees treated with the indicated concentration of octopamine versus buffer controls (t test: *p ≤ 0.05).

Figure 2

The effects of tyramine on honey bee behavioral profiles. The percent of time subjects spent engaged in each behavior is shown for treatment with each concentration of tyramine. Treatment consisted of injection with 2 μl of 5 × 10⁻², 5 × 10⁻³, 5 × 10⁻⁴, 5 × 10⁻⁵ M tyramine or buffer alone. Data represent the average of 10 to 14 independent observations and error bars indicate the SEM. The interval of time post injection is indicated. A) Behavioral profiles are significantly different among bees given different treatments at the 35–40, 40–45 and the 45–50 min intervals. B) Time spent flying versus time after injection for bees treated with tyramine. This is the same data included in the behavioral profiles in A shown on a separate graph to aid comparison. For intervals in which significant differences in behavioral profiles occurred, asterisks indicate significant differences in time spent in that behavior by bees treated with the indicated concentration of tyramine versus buffer controls (t test: * p ≤ 0.05).

Figure 3

The effects of the octopamine receptor antagonist mianserin on honey bee behavioral profiles. The percent of time subjects spent engaged in each behavior is shown for treatment with each concentration of mianserin. Treatment consisted of injection with 2 μl of 5 × 10⁻³, 5 × 10⁻⁴, 5 × 10⁻⁵, 5 × 10⁻⁶ M mianserin or buffer alone. Data represent the average of 10 independent observations and error bars indicate the SEM. The interval of time post injection is indicated. A) Behavioral profiles are significantly different among bees given different treatments at the 30–35 and the 40–45 min intervals. B) Time spent flying versus time after injection for bees treated with mianserin. This is the same data included in the behavioral profiles in A shown on a separate graph to aid comparison. For intervals in which significant differences in behavioral profiles occurred, asterisks indicate significant differences in time spent in that behavior by bees treated with the indicated concentration of mianserin versus buffer controls (t test: * p ≤ 0.05).

Figure 4

The effects of the tyramine receptor antagonist yohimbine on honey bee behavioral profiles. The percent of time subjects spent engaged in each behavior is shown for treatment with each concentration of yohimbine. Treatment consisted of injection with 2 μl of 5 × 10⁻³, 5 × 10⁻⁴, 5 × 10⁻⁵, 5 × 10⁻⁶ M yohimbine or buffer alone. Data represent the average of 12 to 14 independent observations and error bars indicate the SEM. The interval of time post injection is indicated. A) Behavioral profiles are significantly different among bees given different treatments at the 45–50 min interval. B) Time spent flying versus time after injection for bees treated with yohimbine. This is the same data included in the behavioral profiles in A shown on a separate graph to aid comparison. For intervals in which significant differences in behavioral profiles occurred, asterisks indicate significant differences in time spent in that behavior by bees treated with the indicated concentration of yohimbine versus buffer controls (t test: * p ≤ 0.05).