1
Table S1: Results from statistical analysis of surveys of arthropod abundance (aphids, ants and predators)
2
on L. porteri plants (n=100) in shaded understory and open meadow plots over four study years (2011-
3
2014).
4
a. Aphids
χ2 =
P=
Light environment
19.017
1.30E-05
Year (2011-2014)
50.942
5.03E-11
Light environment-x-Year
44.060
1.47E-09
b. Ants
χ2 =
P=
Light environment
0.274
0.601
Year (2012-2014)
0.666
0.717
Light environment-x-Year
42.657
5.46E-10
c. Predators
χ2 =
P=
Light environment
4.205
0.040
Year (2012-2014)
53.734
2.15E-12
Light environment-x-Year
0.373
0.830
5
Table S2: Results from statistical analysis of ant abundance from pitfall traps for ants in aphid-tending
6
taxonomic groups (F. fusca, F. rufa and Tapinoma spp.) at shaded understory (n=3) and open meadow
7
(n=3) plots.
8
9
Model effect
χ2 =
P=
Ant taxonomic group
10.626
0.005
Light environment
3.667
0.056
Ant group-x-Light environment
3.919
0.141
10
Table S3: Results from statistical analysis of aphid population growth rate in trophic level treatments
11
(two, three or four trophic levels) applied to colonies on shaded understory and open meadow plants
12
including overall results (a) and specific comparisons between trophic level treatments (b-c).
a. All trophic level treatments
χ2=
P=
Treatment
67.977
4.241e-07
Light environment
0.013
0.029
Treatment x Light environment
7.006
0.030
b. Two- vs. Three- trophic level treatments
Treatment
61.956
2.289e-06
Light environment
0.237
0.023
Treatment x Light environment
5.656
0.017
c. Three- vs. Four-trophic level treatments
13
14
Treatment
1.220
0.242
Light environment
0.850
0.038
Treatment x Light environment
6.230
0.013
15
Table S4: Statistical results from analysis of ant tending of experimentally shaded aphid colonies and ant
16
mounds.
χ2=
Model effect
17
18
19
20
P=
Ant shading treatment
1.668
0.1813
Plant shading treatment
1.119
0.350
Aphid abundance
52.803
0.0004
Ant treatment-x-Plant treatment
0.445
0.505
Ant treatment-x-Plant treatment-x-Aphid abundance
0.494
0.482
Plant treatment-x-Aphid abundance
5.089
0.024