ANOVAs for the body mass of the two most abundant primary parasitoid species (<i>A. arvicola</i> and <i>T. brevicornis</i>).

The first analysis (a) was done without covariables, the second analysis (b) with biomass and nitrogen concentration of aphid host plants as covariables. Both parasitoid species developed only in aphids on non-legume host plant species. The covariables and “Sex” (incl. all interactions with “Sex”) were tested against “Residuals”, all other terms against “Plotcode”. “Parasitoid identity” was tested at the “Plotcode” level in this analysis because in almost all cases only one of the two species was present in a plot. Directions of significant effects of the covariables are indicated by arrows. P-values<0.05 are printed in bold. % SS = percent sum of squares explained.