Figure 1: Some views of the experiments. A: an ant under normal diet having reached a tied nestmate which emits its alarm pheromone

Figure 1: Some views of the experiments. B: an ant under aluminum diet following for a time a circular trail
Figure 1: Some views of the experiments. C: three ants under aluminum diet not inclined in coming onto an unknown and risky apparatus

Figure 1: Some views of the experiments. D: an ant under aluminum diet moving frankly on a rough, uncomfortable substrate

Figure 1: Some views of the experiments. E: ants under aluminum diet taking care of their brood inside the nest

Figure 1: Some views of the experiments. F: two nestmates under aluminum diet staying side by side with no aggressiveness

Figure 1: Some views of the experiments. G: an ant under aluminum diet stinging an alien. H: an ant under normal diet escaping from an enclosure.

Figure 1: Some views of the experiments. H: an ant under normal diet escaping from an enclosure.

Figure 1:Some views of the experiments. I: ants under aluminum diet unable to escape from an enclosure

Figure 1: Some views of the experiments. J: an ant under aluminum diet, trained to a hollow yellow cube, hesitating to give to correct response when tested in a Y apparatus provided with that cue.

Figure 1: Some views of the experiments. K: an ant under aluminum diet, trained to basilica, giving the correct response when tested in a Y apparatus provided with that cue

Figure 1: Some views of the experiments. L: ants under aluminum diet not preferentially choosing sugar water containing this metal (tube with the red label 'al') when confronted to it and to aluminum-free sugar water (tube with no label)

Figure 2: Decrease of the effect of aluminum on the ants' sinuosity after its consumption was stopped. Numerical and statistical results are given in Table 6, details are provided in the text. The effect of aluminum scarcely decreased during 4 hours, then decresed slowly and linearly during 12 more hours, losing 1/12 of its intensity each hour. Such a slow, regular decrease accounted for the absence of addiction to aluminum use

Sugar water diet Sugar water + aluminum diet
Days Meat Sugar water Activity Meat Sugar water Activity
Daily counts

I     A
      B

1  0  0  1  1  1
0  0  1  1  1  1

2  2  2  1  1  1
0  1  0  1  1  1

7    7     6    9  10  11
15 16 14 16 17  17

0  0  1  1  0  0
1  1  1  0  0  1

2  2  2  1  1  1
0  0  1  1  0  0

16  15 15  9  10   9
 9    10 11 13 14 13

II    A
      B

1  0  0  1  1  0
1  1  1  1  1  0

1  1  1  1  1  1
1  1  0  1  1  2

5    6     7  12 13  13
12 13 12 15 14  16

0  0  1  1  0  0
1  0  0  1  1  1

1  1  1  2  2  2
1  0  0  0  0  1

 9   10 10 12 13 12
12 11 13 15 14 15

III  A
      B

0  0  1  1  0  0
1  0  0  0  0  1

1  1  1  1  1  1
3  3  2  2  2  2

6   6     7   12 14  13
8   8     7   18 16  17

1  0  0  0  0  1
0  0  1  0  0  0

1  1  1  4  3  4
1  2  2  1  1  1

10   9  10 14 15 14
10 11 11 14 15 16

IV  A
      B

0  0  1  1  0  0
1  0  0  1  1  1

1  0  0  1  1  1
1  1  1  1  1  0

8   7     7    9   10   9
10 10 11 18 17 18

1  0  0  1  1  0
0  0  1  0  0  0

1  1  1  1  1  1
0  0  1  1  1  1

 9   10   9  14 15 14
15 14 14  12 13 15

V    A
      B

1  1  1  1  1  0
1  1  1  1  1  1

1  1  1  1  1  0
0  0  1  1  1  1

13 10  11 16 12 14
10   9   11 18 17 18

1  1  1  1  0  0
1  1  2  0  0  1

1  1  1  1  1  0
2  2  2  2  2  2

 8     9    9  13 14 15
12 13 13  22 20 21

VI  A

    B

1  0  0  1  1 0

0  0  1  1  1  1

2  2  2  1  0  1

1  1  1  1  0  0

10 11  12 12 14 13

10 10  11 18 19 18

1  1  0  1  1  0

0  0  0  0  0  1

1  1  1  3  4  3

5  5  5  1  1  1

 9   10   9  20 19 20

15 15 14  22 24 23
Daily means
I 0.66 1.08 12.08 0.50 1.00 12.00
II 0.66 1.00 11.33 0.50 0.92 12.17
III 0.33 1.67 11.08 0.25 1.83 12.42
IV 0.50 0.75 11.16 0.33 0.83 12.83
V 0.92 0.75 13.25 0.75 1.42 14.08
VI 0.58 1.00 13.17 0.42 2.58 16.67
Average of daily means
  0.61 1.04 10.35 0.46 1.43 13.36

Ants of colonies A and B eating meat, drinking sugar water, and being active were counted 6 times per day, during 6 days. The daily means were calculated, as well as the average of these daily means. Experimental details and statistics are given in the text. Aluminum (given in sugar water) somewhat decreased meat consumption, increased sugar water consumption, and increased activity

Table 1: Effect of aluminum on ants’ food consumption, and general activity
Traits Sugar water diet Sugar water + aluminum diet

Linear speed (mm/s)

14.1 (11.7–15.4)

13.7 (12.1–14.8)

Angular speed (ang.deg./cm)

126 (108–147)

148 (132–158)

Orientation (ang. deg.)

38.3 (29.2–53.4)

59.9 (48.1–67.7)

Trail following (n ° arcs)

12.5 (8.0–18.0)

5.0 (3.0–9.0)

Audacity (n ° ants)

1.25 [0 –2]

0.90 [0–2]
Tactile (pain) perception
linear speed (mm/s) 4.7 (4.4–6.2) 8.4 (7.8–9.3)
angular speed (ang.deg./cm) 257 (220–311) 192 (169–205)

Experimental details and statistics are given in the text. Aluminum increased the ants’ sinuosity of movement, decreased their orientation ability, their trail following, their audacity, and largely their tactile perception

Table 2: Effect of aluminum on six physiological and/or ethological traits
 
 
Traits Normal diet Diet with aluminum

Brood caring

           p                i             i/p p i       i/p
 

        143    

          76          0.53

        158

89

0.56

Cognition: ants in front of and beyond twists and turns in the course of 12 min

 t n° in front n° beyond t n° in front n° beyond
  30s   23 0 30s 27 0
  2 18 0 2 23 2
  4 17 1 4 19 2
  6 13 1 6 19 3
  8 11 3 8 17 3
  10 10 4 10 16 3
 

12

10

6

12

16

4

Aggressiveness against nestmates

levels  0    1    2    3    4   var ‘a’

n°       65 42  11  0    0    0.10

levels  0    1    2    3    4   var ‘a’
n°   53  40 15  0    0    0.16

Aggressiveness against aliens

levels  0    1    2    3   4   var ‘a’
n°       5   28  53  56 39   4.50

levels  0    1    2    3   4   var ‘a’
n°      17   21  52 62 39    3.90
Escaping from an enclosure: ants in and out of the enclosure in the course of 12 min

t:        30s   2    4    6   8   10   12
n° in   12   10   8    7   5    3     1
n° out: 0    2    4    5   7    9     11
variable = 11/12 = 0.91

t:        30s   2    4     6   8   10   12
n° in:  12  12  12  12  12   11  10
n° out: 0   0    0    0    0     1     2
variable = 2/12 = 0.17

Experimental details and statistics can be found in the text. Aluminum did not impact the ants’ brood caring and their behavior in front of nestmates and aliens, but largely impacted their cognition and ability in escaping from an enclosure. p: number of ants present on the brood; i: number of ants interacting with the brood; aggressiveness levels: 0: doing nothing, 1: antennal contact, 2: mandibles opening, 3: gripping, 4: stinging; var a =n ° (2+3+4)/n ° (0+1)
Table 3: Effects of aluminum on five physiological and/or ethological traits

time (h)

       Sugar water diet *

sugar water + aluminum diet
  colony C % colony A colony B %
Visual conditioning
7
 7 70 4 6     50
24 8 80 4 6 50
31 8 80 3 5 40
48 8 80 5 6 55
55 8 80 3 6 45
72 8 80 4 6 50
Visual memory
7 8 80 no short and middle term
memory
24 7 70
31 8 80
48 7 70
55 7 70
72 7 70
Olfactory conditioning
7 7 70 3 5 40
24 8 80 5 4 45
31 8 80 5 4 45
48 9 90 4 7 55
55 9 90 5 3 40
72 9 90 5 4 45
Olfactory memory
7 9 90

 

no short and middle term 
memory                  

24 8 80
31 8 80
48 7 70
55 8 80
72 8 80

Ants were trained to a visual, then an olfactory cue, and tested over time in a Y-apparatus provided with the cue in one of its branches. Details and statistics are given in the text. Aluminum drastically impacted the ants’ ability in acquiring conditioning, and thus their short and middle term visual and olfactory memory. *: control results previously obtained in [54]
Table 4: Impact of aluminum on ants’ conditioning ability and memory
Traits

Under normal diet

(control)		 Under AL diet since one or 5 days Under AL diet since 10 or 11 days
Angular speed on a normal substrate 126 (108–147) 148 (132–158) 159 (139–191)

Linear speed
Angular speed
on a rough substrate

4.7 (4.4–6.2)
257 (220–311)

8.4 (7.8–9.3)
192 (169–205)

9.6 (8.8–10.8)
163 (134–180)

Angular speed in ang.deg./cm; linear speed in mm/s; normal diet=sugar water diet; Al diet=sugar water+aluminum diet. These traits, i.e., sinuosity and tactile perception, initially impacted by aluminum (see Table 2), were still impacted after 10 or 11 days of Al ingestion. Ants developed thus no adaptation to the adverse effects of aluminum

Table 5: Adaptation to the impact of aluminum on sinuosity of movement and on tactile perception (i.e., locomotion on a rough substrate)

Experiments time (h)

Angular speed (ang.deg./cm)

 Statistics vs normal diet Statistics vs t = 0
K-W test χ² test K-W test χ² test

Normal diet
1 day Al diet
10 days Al diet

126 (108–147)
148 (132–158)
159 (139–191)

        

0 h: weaning

169 (149–186)

        

then since 2 h
                 4 h
                 6 h
                 8 h
                10 h
                12 h
                14 h
                16 h

167 (147–194)
165 (150–177)
158 (147–177)
153 (131–170)
146 (117–162)
140 (118–158)
133 (116–165)
124 (102–146)

P=0.0002
P=0.0000
P=0.0003
P=0.01
P=0.11
P=0.11
P=0.11
P=0.11

0.001<P<0.01
P<0.001
0.001<P<0.01
0.05<P<0.10 
P = 0.30
P = 0.80  
0.30<P<0.50
0.70<P<0.80

P=0.0508
P=0.045
P=0.049
P=0.017
P=0.1035
P=0.039
P=0.035
P=0.0003

P=0.80
P=1
P=0.90
0.50<P<0.70
0.20<P<0.30
0.05<P<0.10
0.10<P<0.20
P~0.001

After having again assessed the ants’ sinuosity while under aluminum diet (note that the effect of aluminum on that trait increased over its consumption time), weaning began when the ants’ solution of aluminum was replaced by pure sugar water. Since that time t=0, the ants’ sinuosity was assessed until it equaled again the control one. The effect of aluminum decreased slowly, linearly over time, and vanished in 15 to 16 hours. The ants’ sinuosity in function of weaning time is plotted in Figure 2. Details are given in the text. Columns 3 and 4: statistical comparison with control values; columns 5 and 6: statistical comparison with values at t=0; K-W test=non-parametric Kruskall-Wallis ANOVA; χ²test=non-parametric χ² test (bilateral tests)

Table 6: Loss of the impact of aluminum on the ants’ sinuosity of movement after its consumption was stopped