First published online March 12, 2009
Journal of Experimental Biology 212, 1032-1035 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.022582
Mechanisms of food provisioning of honeybee larvae by worker bees
Christina Heimken,
Pia Aumeier and
Wolfgang H. Kirchner*
Ruhr-Universität Bochum, Fakultät für Biologie und
Biotechnologie, Bochum, Germany
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Fig. 1. (A) Number of food provisioning visits to brood cells containing
food-deprived (N=15) and control larvae (N=26) per 30 min.
Food-deprived larvae (2 h food deprivation) are fed significantly more often
than the controls (**P<0.01; U-test). (B) The
same effect is found when workers are allowed to patrol on the rims of the
cells during food deprivation (3 h food deprivation) of the larvae
(N=54 each, ***P<0.001; Mann–Whitney
U-test, outlier indicated by open circle).
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Fig. 2. Bees can be trained to exhibit a proboscis extension reflex (PER) in
response to the odour of larvae. They can discriminate between the smell of
well-fed control larvae used as the conditioned stimulus (CS) and the smell of
larvae that have been food deprived (reference scent, RS; N=76 bees,
*P<0.05; Wilcoxon test). Bees trained to respond to the
smell of hungry larvae respond to the smell of well-fed controls as frequently
(N=73, P>0.05; n.s., not significant).
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Fig. 3. Bees can be trained to respond to extracts of larval food by exhibiting the
PER. (A) Conditioned responses to the odours of pentane extracts of 100 and 10
mg larval food were significantly greater than those to the solvent control
stimulus (N=19 and 40, respectively, *P<0.05
in both series; Wilcoxon test). (B) The bees significantly prefer the higher
concentration of larval food odour when trained to respond to the higher of
two concentrations (N=20 in each series,
*P<0.05; Wilcoxon test), but do not significantly
prefer the lower concentration when trained to respond to the lower one
(N=20 in each series, P>0.05; n.s.).
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Fig. 4. Artificial `cells' containing (A) a small amount (2–5 mg) of larval
food are more attractive than empty cells (N=60 trials,
**P<0.01; Wilcoxon test) and cells containing (B) 10 mg
larval food are more attractive than cells containing 5 mg food (N=87
trials, ***P<0.001; Wilcoxon test). Outliers indicated
by open circles.
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Fig. 5. Principal components analysis of the gas chromatograms of pentane extracts
of food-deprived (filled circles) and well-fed control larvae (open circles).
The analysis is based on 161 components of the extracts. Component 1 explains
29.5% of the variability, component 2 another 13.1%. Although there is a
slight overlap between the samples taken from hungry and control larvae there
seem to be components available for olfactory discrimination between the
signals of hungry and well-fed larvae.
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Fig. 6. Changes of larval pace following supply of food. After food deprivation,
larvae show an initial increase in speed of rotation (N=5 trials;
number of larvae per trial, 67±15 food deprived, 56±15 control;
P<0.05, U-test). After 3–4 h pace again complies
with the control (N=5 trials), and after 6 h (N=2 trials)
the larvae move slower than untreated ones (P<0.05 in one of the
two trials).
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© The Company of Biologists Ltd 2009
