A carbohydrate-rich diet increases social immunity in ants
Adam D. Kay, Abbie J. Bruning, Andy Van Alst, Tyler T. Abrahamson, W.O.H. Hughes,
Michael Kaspari
Table S1. Components of experimental diets used in this study. The baseline diet is from
Dussutour and Simpson (2008); sources for ingredients are listed in Kay et al. (2012). Egg
powder amount is kept constant across diets to equalize diet lipid content; P:C ratio is modified
by changing amounts of whey protein, calcium caseinate, and sucrose.
Diet P:C ratio
Ingredients:
Final volume (ml)
Dried egg powder (g)
Whey protein (g)
Calcium caseinate (g)
Sucrose (g)
Agar (g)
Vanderzant vitamin mixture (g)
Methyl 4-hydroxybenzoate (g)
protein (% of dry mass)
carbohydrate (% of dry mass)
3:1
200
2.34
9.26
7.6
4.16
2
0.54
0.26
0.287
0.096
1:3
200
2.34
2.60
2.14
14.74
2
0.54
0.26
0.102
0.305
A carbohydrate-rich diet increases social immunity in ants
Adam D. Kay, Abbie J. Bruning, Andy Van Alst, Tyler T. Abrahamson, W.O.H. Hughes,
Michael Kaspari
Table S2. Results from Cox Proportional Hazards analysis of worker survival data. “Diet” =
dietary protein:carbohydrate (P:C) ratio (either 1P:3C or 3P:1C). “Social”= whether ants in
survival assays were alone or in 5-ant groups. “Year”= the study was replicated in 2011 and
2012. “Met” = whether ants were treated with LD50 concentration of Metarhizium anisopliae or a
control solution. All ants were treated with Metarhizium in 2011 (there were controls only in
2012).
a. Worker survivorship, Metarhizium-treated ants, both years
Source
diet
social
year
diet*social
diet*year
year*social
diet*social*year
DF
1
1
1
1
1
1
1
L-R Chi Square
15.886
86.871
24.748
10.499
6.039
3.860
0.689
P
<0.0001
<0.0001
<0.0001
0.0012
0.0140
0.0494
0.4066
b. Worker survivorship, controls
Source
diet
social
diet*social
DF
1
1
1
L-R Chi Square
36.143
5.541
0.081
P
<0.0001
0.0186
0.7765
A carbohydrate-rich diet increases social immunity in ants
Adam D. Kay, Abbie J. Bruning, Andy Van Alst, Tyler T. Abrahamson, W.O.H. Hughes,
Michael Kaspari
Figure S1 Food consumption by the ant Ectotomma ruidum in experiments testing effects of
dietary protein:carbohydrate (P:C) ratio on worker- and colony-level resistance to challenge from
Metarhizium anisopliae (Met in legend), a parasitic fungus. Explanation of figure legend: 1P:3C
(or 3P:1C) control, larvae = colonies (workers, pupae, and larvae) reared without facing
Metarhizium challenge; 1P:3C (or 3P:1C) Met, no larvae = colonies (workers, pupae) were
reared and challenged with two ant cadavers covered in Metarhizium spores. 1P:3C (or 3P:1C)
Met, larvae = as above, but colonies had larvae. Rearing in all conditions was conducted in both
June 2011 and Jan 2012. In one analysis, we compared intake for colonies with larvae reared on
the 1P:3C or 3P:1C diet with or without challenge from Metarhizium-covered cadavers. In this
analysis, colonies on the 1P:3C diet consumed significantly more carbohydrates (F1,77 = 11.944,
P < 0.001) and less protein (F1,77 = 45.529, P < 0.001) than those on the 3P:1C diet. Metarhizium
challenge did not significantly affect intake of carbohydrates (F1,77 = 0.505, P = 0.480) or protein
(F1,77 = 1.092, P = 0.300), but there was a significant diet-by-Metarhizium interactive effect on
protein consumption (F1,77 = 5.294, P = 0.024), as colonies on the 3P:1C diet increased
consumption when exposed to Metarhizium. In a second analysis, we compared intake for
colonies facing Metarhizium challenge on the 1P:3C or 3P:1C diet with or without larvae. In this
analysis, colonies on the 1P:3C diet consumed significantly more carbohydrates (F1,49 = 38.579,
P < 0.001) and less protein (F1,49 = 108.698, P < 0.001) than those on the 3P:1C diet. The
presence of larvae did not significantly affect intake of carbohydrates (F1,49 = 0.248, P = 0.621);
the effect on protein intake was almost significant (F1,49 = 3.545, P = 0.066). The interaction
between diet and larval presence was not significant for carbohydrate intake (F1,49 = 0.227, P =
0.636), and was almost significant for protein intake (F1,49 = 3.514, P = 0.068).
June 2011
1P:3C control, larvae
3P:1C control, larvae
1P:3C Met, no larvae
3P:1C Met, no larvae
1P:3C Met, larvae
3P:1C Met, larvae
0.4
Carbohydrate intake
(mg worker-1 day-1)
Jan 2012
0.3
0.2
0.1
0.0
0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
Protein intake (mg worker-1 day-1)
0.3
0.4