Immune measures
Immune measures
(circulating
hemocytes, presence of microaggregations, antibacterial activity) of 137
males were taken immediately after calling effort trials (sample sizes
for diet type and infection cue dose included in appendix table A1).
Prior mortality resulting from diet and infection cue treatments limits
our interpretation of these data.
Neither diet type (χ2 1,131 =
2.275; p = 0.1315) nor infection cue
(χ2 4,131 = 2.533; p =
0.6387) significantly influenced the number of circulating hemocytes;
the nonsignificant interaction between diet and infection cue
(χ2 4,124 = 5.421; p =
0.2468) was removed from analysis. However, the presence of circulating
microaggregations of hemocytes was significantly influenced by both
pronotum width (χ2 1,123 =
4.237; p = 0.0396) and the interaction between diet type and
infection cue (χ2 4,123 =
10.472; p = 0.0332). Larger males were more likely to have
circulating microaggregations (see appendix Fig. A1). Males fed on the
high carbohydrate diet were less likely to have circulating
microaggregations if they received the high infection cue dose, and this
also tended to be true for males fed the high protein diet and receiving
a moderate infection cue dose (Fig. A1).
For antibacterial activity of hemolymph, we found a nonsignificant trend
for infection cue to affect the zone of growth inhibition of M.
luteus (F4,125 = 2.293; p = 0.0631), with
antibacterial activity lowest at the high infection cue dose (estimated
marginal means ± standard error: naive = 2.248 ± 0.487, sham = 1.457 ±
0.322, low = 1.567 ± 0.326, moderate = 2.189 ± 0.490, high = 0.944 ±
0.218). However, diet type did not significantly influence antibacterial
activity (F1,125 = 0.9194; p = 0.33949; estimated
marginal means ± standard error: high protein = 1.66 ± 0.251, high
carbohydrate = 1.41 ± 0.172).