First published online April 18, 2006
Journal of Experimental Biology 209, 1777-1783 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02170
The role of visual cues in directed aerial descent of Cephalotes atratus workers (Hymenoptera: Formicidae)
S. P. Yanoviak1,2,* and
R. Dudley3,4
1 Department of Pathology, University of Texas Medical Branch, Galveston,
Texas 77555, USA
2 Florida Medical Entomology Laboratory, 200 9th Street SE, Vero
Beach, Florida 32962, USA
3 Department of Integrative Biology, University of California, Berkeley,
California 94720, USA
4 Smithsonian Tropical Research Institute, Apdo. 2072, Balboa, Republic of
Panama

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Fig. 1. Experimental configuration of colored sheets used to evaluate preference in
falling ants. The sheets were suspended from a more sheltered location
(platform 5-B) for experiments. The arrangement shown here corresponds to run
#7 (Table 1).
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Fig. 2. Diagram of experimental arrangement as viewed from above (top) and
potential landing points as viewed laterally and perpendicularly to the array
of sheets (bottom). The null frequency of contact with a sheet is a function
of distance from the drop point (P) to its landing position (AE).
Relative to the most direct path (i.e. from P to C), the distance from P to A
or to E is 5.1% greater, and from P to B or to D is 1.3% greater. Thus, the
proportions used to calculate null frequencies for G-tests were:
0.195 (landing points A and E), 0.203 (landing points B and D) and 0.205
(landing point C).
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Fig. 3. Reflectance profiles for each of the six colored sheets. Each point
represents the mean (±95% C.I.) of five separate measurements.
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Fig. 4. Reflectance profiles for the four sheets used to assess the ants'
attraction to targets of different brightness. Each point represents the mean
(±1 s.d.) of five measurements. Some points and error bars were omitted
for clarity.
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Fig. 5. Reflectance profiles for tree trunks (squares, N=21) and
surrounding vegetation (circles, N=51 plants). Each point represents
the average (±95% C.I.) of the median reflectance values obtained from
40100 measurements per tree trunk, and from 15 leaf measurements per
plant.
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Fig. 6. Proportion of dropped ants landing on each of the colored sheets. Values
are means ± s.e.m.; N=7 trials for dark gray, gray, green and
blue, N=21 for white and black and N=14 for all others;
2738 ants dropped per trial. Bk, black; Dk, dark gray; Gy, gray; Wh,
white; Yl, yellow; Rd, red; Bu, blue; Gr, green. Similar letters indicate lack
of difference between means.
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Fig. 7. Glide index (horizontal distance/vertical distance) for ants landing on
each colored sheet presented individually. Bk, black; Dk, dark gray; Gy, gray;
Wh, white; Yl, yellow; Rd, red; Bu, blue; Gr, green. Values are means
±95% C.I.; number pairs indicate the number landing on each sheet out
of the total number dropped (i.e. the first in each pair is the sample size
for the plotted mean).
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© The Company of Biologists Ltd 2006