First published online December 26, 2008
Journal of Experimental Biology 212, 163-168 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.025361
Effects of cocaine on honey bee dance behaviour
Andrew B. Barron1,2,*,
Ryszard Maleszka1,
Paul G. Helliwell1 and
Gene E. Robinson2
1 ARC Centre for Molecular Genetics of Development, Research School of
Biological Sciences, Australian National University, Canberra, ACT 2601,
Australia
2 Department of Entomology and Neuroscience Program, University of Illinois at
Urbana-Champaign, 505 S. Goodwin Avenue, Urbana, IL 61801, USA

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Fig. 1. Effect of cocaine (COC) on the likelihood and rate of round dancing by bees
returning from a 1.5 mol l–1 sucrose feeder. Bees were
treated with one of three doses of cocaine or octopamine (OA) dissolved in DMF
at the feeder. DMF- and sham-treated bees served as controls. N>34
bees per group. Differences between treatment groups were tested with
Kruskal-Wallis tests, and comparisons between specific groups were performed
using Dunn's post hoc tests. Groups that did not differ (Dunn's
post hoc test, P>0.05) are marked by the same letter
above the bars. (A) Likelihood of each bee dancing, calculated as the
proportion of visits to the feeder that resulted in a dance during the 50-min
observation period. Bars represent means and standard error calculated from
arcsin-transformed values and consequently are not always symmetrical around
the mean. (B) Number of dance circuits per minute. Bars represent means and
standard error. Since our statistical comparisons used nonparametric methods,
the standard error provides an indication of the distribution of the data but
is less indicative of calculated significant differences between groups.
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Fig. 2. Effect of mianserin (MI) on the stimulation of dancing by cocaine (COC).
Dance likelihood (A) and dance rate (B) of bees treated with MI and COC for a
1.5 mol l–1 sucrose feeder were compared with dances of bees
treated with COC alone and DMF- and sham-treated controls (N>39
bees per group). Bar plots, analyses and statistical notation as in
Fig. 1.
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Fig. 3. Effect of cocaine on locomotion. The movement index measured the amount
that DMF- (white bars) and cocaine-treated bees (black bars) moved in a Petri
dish during 5 min observation periods 30 and 60 min post-treatment. Bars show
mean and standard error. N=20 for each group. Data were analysed with
two-way ANOVA. There was no significant effect of drug (F=0.09,
P=0.7600) or time (F=0.04, P=0.8418) and no
significant interaction between these factors (F=0.83,
P=0.3694).
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Fig. 4. Effect of cocaine (COC) on sucrose responsiveness. 20 µl drops of seven
different sucrose solutions ranging in concentration from 0.1% sucrose to 60%
sucrose were presented to the antennae of harnessed bees in the laboratory.
The first sugar solution (1–7) eliciting proboscis extension was the
sucrose sensitivity index; therefore a lower value indicates higher sucrose
sensitivity. Bars show means and 95% confidence intervals. Differences between
treatment groups were tested with Kruskal-Wallis tests (median sucrose
sensitivity index: 3 µg cocaine, 3; DMF, 4; untreated, 5. Kruskal-Wallis
statistic 24.17, d.f.=2, P<0.001) and comparisons between specific
groups were performed using Dunn's post hoc tests. Bars that do not
differ significantly (Dunns post hoc test, P>0.05) are
marked by the same letter above the bar. Sample size shown in bars.
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Fig. 5. Effect of cocaine (COC) withdrawal on learning. Relative proportion of bees
responding correctly in a proboscis extension response (PER) learning assay 20
h after three trials of training. Prior to training, bees were orally treated
for 6 days with 10.54 mmol l–1 octopamine (OA) or 0.66 mmol
l–1 cocaine (COC) in ad libitum 1.5 mol
l–1 sucrose solution, or plain 1.5 mol l–1
sucrose. (A) Chronic treatment: bees continued to receive treatment during the
20 h interval between training and testing. (B) Withdrawal: treatment withheld
during the 20 h interval between training and testing. In each panel the
proportion of bees responding correctly is normalized with respect to the
untreated control group. Sample size is shown in bars. Groups that did not
differ at the 5% confidence interval share the same letter above the bar
(pair-wise Fisher's exact tests with Bonferroni correction).
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© The Company of Biologists Ltd 2009