First published online October 7, 2005
Journal of Experimental Biology 208, 3945-3955 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01833
Look and turn: landmark-based goal navigation in honey bees
S. N. Fry1,* and
R. Wehner2
1 Institute of Neuroinformatics, ETH/University of Zürich
2 Institute of Zoology, University of Zürich, Winterthurerstrasse 190,
CH-8057 Zürich, Switzerland
View larger version (17K):
[in a new window]
|
Fig. 1. Cylindrical flight chamber (height and diameter, 2.4 m). The circular floor
is filmed from above using a video camera (VC). Bees entered the tent through
the entry tube (ET), attached to a white painted side wall (SW). Bees flew to
the 1.9 m-distant food hole (FH), which gave access to a feeder (not shown).
Discs on the floor provided visual feedback. The inset shows a plan view of
the set-up with the locations of the landmarks used in the experiments: (1)
paper square (side length, 25 cm); (2, 3) cylinder (diameter and height, 25
cm) located 0.5 m to the side of the food hole; (4) same cylinder, located 1 m
to the right of the center.
|
|
View larger version (29K):
[in a new window]
|
Fig. 2. Learning experiments. (A) Successive flights of a bee trained with a single
landmark. (i) Flights to a feeder while it was moved toward the final training
position. The feeder was moved on the connecting line between entry (black
square) and center of landmark (thin line at far right). Arrows point to
feeder positions. A single unsuccessful flight was excluded. (ii) Flights
1–20 performed after the bee learnt the final feeder position. (iii)
Flights 51–70. (iv) Flights 101–120, after which the bee ceased to
return. (B) Flight duration over successive flights after training. The
duration of the approach to within 25 cm of the food hole of 119 successive
flights is shown as dots, together with a smoothed spline function to
emphasize the trend. Five unsuccessful approach flights were excluded from the
analysis. Numbers with lines indicate days at which experiments were
performed.
|
|
View larger version (14K):
[in a new window]
|
Fig. 3. Approach flights of a single bee trained with a black square landmark
located behind the food hole (shown in black; position 1 in inset of
Fig. 1) and tested with the
landmark shifted to –20° (yellow), –10° (blue), 0°
(black, control), 10° (red) and 20° (green) with respect to training
position, as seen from the entry position (small black square). (A) Typical
sample flights. (B) Median approach flights. Trajectories are shown with thick
lines where the approach direction differs significantly from the control
(Watson–Williams test for two samples, P=5%;
Zar, 1999 ). Total number of
flights analyzed was 47.
|
|
View larger version (33K):
[in a new window]
|
Fig. 4. Analysis of body axis orientation. (A) Sample flight of a bee, measured at
intervals of 1/50 s (dots). Lines associated with larger dots indicate the
body axis direction, as measured from image analysis. For clarity, body axis
direction is only shown at intermittent positions. (B) Correlation between
body axis direction as measured from image analysis and inferred from path
analysis. The analysis is based on 437 flights (obtained from five bees, of
which data are shown in Figs 6
and 8). Portions of flight at
speeds below 0.5 m s–1 were omitted. The coefficients of the
regression (y=ax+b) are: a=0.982, b=0.96;
r2=0.993. Red lines indicate 95% confidence intervals.
|
|
View larger version (21K):
[in a new window]
|
Fig. 5. Experiments with a single frontal landmark. (i) Approach flights of four
bees (A–D; n=16, 13, 41, 40, respectively). The location of the
food hole is indicated by a green cross, the median search position with a red
dot. (ii) Landmark azimuth distributions (bin width: 5°). 0° indicates
frontal; negative and positive angles represent the left and right visual
field of the bee, respectively.
|
|
View larger version (25K):
[in a new window]
|
Fig. 6. Experiments with a single lateral landmark. (Ai) 40 successive approach
flights of an individual bee with a cylinder positioned at an angular distance
of 15° from the food hole. (Aii) Landmark azimuth distribution.
(B–D) Same as in A, except that the cylinder was located at an angular
distance of 40° during training and test. Also see legend of
Fig. 5 for further details.
|
|
View larger version (11K):
[in a new window]
|
Fig. 7. Experiments with two black landmarks. (A) Examples of training flights. A
typical flight of each of seven trained bees is shown. (B) Data obtained under
training conditions, based on 116 flights performed by seven bees. (Bi) Median
approach flight of each bee. (Bii) Distribution of landmark azimuths of the
left and right training landmark (as seen from the approaching bee's
perspective), shown in black and red, respectively. (C) Experiment with right
landmark removed. (Ci) Median approach trajectories (N=7,
n=13) tested with the right landmark removed. (Cii) Azimuth of the
left landmark. (D) Experiment as in C, but with the left landmark removed
(N=7, n=25). The location of the food hole is indicated by a
green cross.
|
|
View larger version (14K):
[in a new window]
|
Fig. 8. Experiments with two differently colored landmarks. (Ai) Sample flights
from two bees under standard conditions. (Aii) Median approach flights of the
two bees (n=135, 175). (Aiii) Azimuth of the green and blue
cylinders, shown in their respective colors. (B) Same experiments as in A but
with landmarks interchanged (n=27, 29).
|
|
View larger version (18K):
[in a new window]
|
Fig. 9. Visuo-motor guidance model. (A) Frontal landmark, symmetric response. (B)
Lateral landmark, biased response. (C) Two black cylinders, symmetric
response. (D) Cylinders of different color, biased response to green cylinder.
Red arrows indicate hypothetical approach paths from the entry (black square)
to the food hole (cross). Curved arrows indicate the strength with which
landmarks are `pushed out' of each hemisphere by compensatory turning
reactions. For example, in D, the thick green arrow indicates a strong
(anti-clockwise) turning response for right-to-left movement of the green
cylinder. For details, see text.
|
|
© The Company of Biologists Ltd 2005
