First published online February 6, 2004
Journal of Experimental Biology 207, 993-1004 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00850
Allometry of kinematics and energetics in carpenter bees (Xylocopa varipuncta) hovering in variable-density gases
Stephen P. Roberts1,*,
Jon F. Harrison2 and
Robert Dudley3,4
1 Department of Biological Sciences, University of Nevada, Las Vegas, 4505
S. Maryland Parkway, Las Vegas, NV 89154-4004, USA
2 School of Life Sciences, Arizona State University, Tempe, AZ 85287-1501,
USA
3 Department of Integrative Biology, University of California, Berkeley, CA
94720-3140, USA
4 Smithsonian Tropical Research Institute, PO Box 2072, Balboa, Republic of
Panama

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Fig. 1. Relative thoracic muscle mass (Mmuscle) vs
body mass (Mb) for female Xylocopa varipuncta.
Model II regression:
Mmuscle=0.6820.411Mb,
r29=0.78, P<0.001.
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Fig. 2. Minimal gas density (MGD) necessary for hovering flight
vs relative thoracic muscle mass for female Xylocopa
varipuncta. Model II regression:
MGD=1.5362.256Mmuscle,
r28=0.86, P<0.001.
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Fig. 3. Wingbeat frequency during hovering in normodense air
(fnorm; open symbols) and during maximal hovering in
hypodense air (fmax; filled symbols) vs body mass
(Mb) for Xylocopa varipuncta females. Model II
regression: fnorm=101.92+24.70Mb,
r27=0.53, P<0.005 (broken line);
fmax=141.3320.09Mb,
r26=0.15, P=0.44.
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Fig. 6. Stroke plane angle during normal (ßnorm; open symbols) and
maximal hovering (ßmax; filled symbols) vs body mass
(Mb) for Xylocopa varipuncta females. Model II
regression: ßnorm=14.289.23Mb,
r29=0.49, P<0.005 (broken line);
ßmax=10.1610.01Mb,
r28=0.26, P=0.17.
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Fig. 7. Log body mass (Mb)-specific power output during normal
(Pbody,norm; open symbols) and maximal hovering flight
(Pbody,max; filled symbols) vs log
Mb for Xylocopa varipuncta females. Assumed drag
coefficient (CD)=1 (bottom panel) and 3 (top panel). Model
II regression for CD=1: log
Pbody,norm=1.979+0.516(log Mb),
r27=0.43, P<0.02 (solid line); log
Pbody,max=2.004+0.405(log Mb),
r26=0.32, P=0.11. Model II regression for
CD=3: log Pbody,norm=2.380+0.633(log
Mb), r27=0.29, P=0.13; log
Pbody,max=2.662+3.890(log Mb),
r26=0.02, P=0.89.
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Fig. 8. Log muscle mass-specific power output during normal
(Pmuscle,norm; open symbols) and maximal hovering flight
(Pmuscle,max; filled symbols) vs log body mass
(Mb) for Xylocopa varipuncta females. Assumed
drag coefficient (CD)=1 (bottom panel) and 3 (top panel).
Model II regression for CD=1: log
Pmuscle,norm=2.517+1.126(log Mb),
r27=0.82, P<0.001 (broken line); log
Pmuscle,max=2.538+1.007(log Mb),
r26=0.81, P<0.001 (solid line). Model II
regression for CD=3: log
Pmuscle,norm=2.909+1.160(log Mb),
r27=0.76, P<0.001 (broken line); log
Pmuscle,max=3.210+4.762(log Mb),
r26=0.17, P=0.38.
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Fig. 9. Reserve capacity (%) in muscle mass-specific power output
(Pres) vs body mass (Mb) for
hovering Xylocopa varipuncta females. Assumed drag coefficient
(CD)=1 (bottom panel) and 3 (top panel). Model II
regression for CD=1:
Pres=47.7047.85Mb,
r26=0.37, P=0.05 (solid line). Model II
regression for CD=3:
Pres=54.7459.05Mb,
r26=0.11, P=0.59.
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Fig. 10. Mean lift coefficient during normal (CL,norm; open
symbols) and maximal (CL,max; filled symbols) hovering
flight vs body mass (Mb) for Xylocopa
varipuncta females. Model II regression:
CL,norm=0.645+0.994Mb,
r27=0.25, P=0.20;
CL,max=2.6781.236Mb,
r26=0.26, P=0.18.
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Fig. 11. Body mass-specific metabolic rate during hovering flight (W
kg1) vs gas density. Numbers in parentheses
indicate the sample sizes at each air density. Error bars represent ± 1
S.E.M.
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Fig. 12. Log body mass-specific metabolic rate during normal
(Pmet,norm; open symbols) and maximal hovering flight
(Pmet,max; filled symbols) vs log body mass
(Mb) for Xylocopa varipuncta females. Model II
regression: log Pmet,norm=2.4830.883(log
Mb), r22=0.53,
P<0.02 (broken line); log
Pmet,max=2.5561.216(log Mb),
r22=0.64, P<0.001 (solid line).
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© The Company of Biologists Ltd 2004