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Differences in the phototaxis of pollen and nectar foraging honey bees are related to their octopamine brain titers.

Scheiner R, Toteva A, Reim T, Søvik E, Barron AB - Front Physiol (2014)

Bottom Line: Our results show that groups of bees differ naturally in their phototaxis.Increasing octopamine brain titers reduces responsiveness to light, while tyramine application enhances phototaxis.These findings suggest an involvement of octopamine signaling in honey bee phototaxis and possibly division of labor, which is hypothesized to be based on individual differences in sensory responsiveness.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biology, University of Potsdam Potsdam, Germany.

ABSTRACT
The biogenic amine octopamine is an important neuromodulator, neurohormone and neurotransmitter in insects. We here investigate the role of octopamine signaling in honey bee phototaxis. Our results show that groups of bees differ naturally in their phototaxis. Pollen forgers display a lower light responsiveness than nectar foragers. The lower phototaxis of pollen foragers coincides with higher octopamine titers in the optic lobes but is independent of octopamine receptor gene expression. Increasing octopamine brain titers reduces responsiveness to light, while tyramine application enhances phototaxis. These findings suggest an involvement of octopamine signaling in honey bee phototaxis and possibly division of labor, which is hypothesized to be based on individual differences in sensory responsiveness.

No MeSH data available.


Phototaxis and locomotion of nectar foragers treated with octopamine 10−3 mol/l or octopamine 10−2 mol/l. For phototaxis (A,C), mean walking time towards the different light intensities and standard errors are shown. For locomotion (B,D), mean walking speed in the dark arena and standard errors are given. (A) Bees treated with octopamine (10−3 mol/l) walked significantly more slowly to the different light sources than control bees treated with sucrose (P ≤ 0.01, ANOVA, effect of treatment). (B) This difference in phototaxis was independent of their locomotion in the dark arena, which did not differ between groups (P > 0.05, ANOVA, effect of walking speed in the dark). (C) Bees treated with octopamine (10−2 mol/l) did not differ in their phototaxis from controls treated with sucrose (P > 0.05, ANOVA, effect of treatment). (D) Locomotion in the dark arena also did not differ between the two groups (P > 0.05, ANOVA, effect of walking speed in the dark). The number of bees tested is indicated in brackets behind each group. Groups not differing from each other are marked with “n.s.”
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Figure 4: Phototaxis and locomotion of nectar foragers treated with octopamine 10−3 mol/l or octopamine 10−2 mol/l. For phototaxis (A,C), mean walking time towards the different light intensities and standard errors are shown. For locomotion (B,D), mean walking speed in the dark arena and standard errors are given. (A) Bees treated with octopamine (10−3 mol/l) walked significantly more slowly to the different light sources than control bees treated with sucrose (P ≤ 0.01, ANOVA, effect of treatment). (B) This difference in phototaxis was independent of their locomotion in the dark arena, which did not differ between groups (P > 0.05, ANOVA, effect of walking speed in the dark). (C) Bees treated with octopamine (10−2 mol/l) did not differ in their phototaxis from controls treated with sucrose (P > 0.05, ANOVA, effect of treatment). (D) Locomotion in the dark arena also did not differ between the two groups (P > 0.05, ANOVA, effect of walking speed in the dark). The number of bees tested is indicated in brackets behind each group. Groups not differing from each other are marked with “n.s.”

Mentions: Octopamine-treated foragers walked significantly more slowly toward light and thus displayed a reduced light responsiveness compared to controls (Figure 4A). The octopamine effect was dose-dependent with octopamine in the concentration of 10−3 mol/l yielding a significant effect [Figure 4A; F(1, 68) = 6.76, P = 0.01; ANOVA effect of treatment), while octopamine 10−2mol/l had no significant effect on light responsiveness [Figure 4C; F(1, 67) = 1.67, P > 0.05; ANOVA effect of treatment]. Neither treatment affected walking speed in the dark arena [10−3 mol/l: Figure 4B; F(1, 68) = 1.59, P > 0.05; ANOVA effect of walking speed in the dark; 10−2 mol/l: Figure 4D: F(1, 67) = 2.08, P > 0.05; ANOVA effect of walking speed in the dark]. If the walking speed of the bees in the dark arena is indicative of their walking speed in the light, our findings suggests that the slower walking speed of the octopamine-treated bees toward the lights is mostly related to their different evaluation of the light sources and not to a generally reduced locomotion.


Differences in the phototaxis of pollen and nectar foraging honey bees are related to their octopamine brain titers.

Scheiner R, Toteva A, Reim T, Søvik E, Barron AB - Front Physiol (2014)

Phototaxis and locomotion of nectar foragers treated with octopamine 10−3 mol/l or octopamine 10−2 mol/l. For phototaxis (A,C), mean walking time towards the different light intensities and standard errors are shown. For locomotion (B,D), mean walking speed in the dark arena and standard errors are given. (A) Bees treated with octopamine (10−3 mol/l) walked significantly more slowly to the different light sources than control bees treated with sucrose (P ≤ 0.01, ANOVA, effect of treatment). (B) This difference in phototaxis was independent of their locomotion in the dark arena, which did not differ between groups (P > 0.05, ANOVA, effect of walking speed in the dark). (C) Bees treated with octopamine (10−2 mol/l) did not differ in their phototaxis from controls treated with sucrose (P > 0.05, ANOVA, effect of treatment). (D) Locomotion in the dark arena also did not differ between the two groups (P > 0.05, ANOVA, effect of walking speed in the dark). The number of bees tested is indicated in brackets behind each group. Groups not differing from each other are marked with “n.s.”
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Figure 4: Phototaxis and locomotion of nectar foragers treated with octopamine 10−3 mol/l or octopamine 10−2 mol/l. For phototaxis (A,C), mean walking time towards the different light intensities and standard errors are shown. For locomotion (B,D), mean walking speed in the dark arena and standard errors are given. (A) Bees treated with octopamine (10−3 mol/l) walked significantly more slowly to the different light sources than control bees treated with sucrose (P ≤ 0.01, ANOVA, effect of treatment). (B) This difference in phototaxis was independent of their locomotion in the dark arena, which did not differ between groups (P > 0.05, ANOVA, effect of walking speed in the dark). (C) Bees treated with octopamine (10−2 mol/l) did not differ in their phototaxis from controls treated with sucrose (P > 0.05, ANOVA, effect of treatment). (D) Locomotion in the dark arena also did not differ between the two groups (P > 0.05, ANOVA, effect of walking speed in the dark). The number of bees tested is indicated in brackets behind each group. Groups not differing from each other are marked with “n.s.”
Mentions: Octopamine-treated foragers walked significantly more slowly toward light and thus displayed a reduced light responsiveness compared to controls (Figure 4A). The octopamine effect was dose-dependent with octopamine in the concentration of 10−3 mol/l yielding a significant effect [Figure 4A; F(1, 68) = 6.76, P = 0.01; ANOVA effect of treatment), while octopamine 10−2mol/l had no significant effect on light responsiveness [Figure 4C; F(1, 67) = 1.67, P > 0.05; ANOVA effect of treatment]. Neither treatment affected walking speed in the dark arena [10−3 mol/l: Figure 4B; F(1, 68) = 1.59, P > 0.05; ANOVA effect of walking speed in the dark; 10−2 mol/l: Figure 4D: F(1, 67) = 2.08, P > 0.05; ANOVA effect of walking speed in the dark]. If the walking speed of the bees in the dark arena is indicative of their walking speed in the light, our findings suggests that the slower walking speed of the octopamine-treated bees toward the lights is mostly related to their different evaluation of the light sources and not to a generally reduced locomotion.

Bottom Line: Our results show that groups of bees differ naturally in their phototaxis.Increasing octopamine brain titers reduces responsiveness to light, while tyramine application enhances phototaxis.These findings suggest an involvement of octopamine signaling in honey bee phototaxis and possibly division of labor, which is hypothesized to be based on individual differences in sensory responsiveness.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biology, University of Potsdam Potsdam, Germany.

ABSTRACT
The biogenic amine octopamine is an important neuromodulator, neurohormone and neurotransmitter in insects. We here investigate the role of octopamine signaling in honey bee phototaxis. Our results show that groups of bees differ naturally in their phototaxis. Pollen forgers display a lower light responsiveness than nectar foragers. The lower phototaxis of pollen foragers coincides with higher octopamine titers in the optic lobes but is independent of octopamine receptor gene expression. Increasing octopamine brain titers reduces responsiveness to light, while tyramine application enhances phototaxis. These findings suggest an involvement of octopamine signaling in honey bee phototaxis and possibly division of labor, which is hypothesized to be based on individual differences in sensory responsiveness.

No MeSH data available.