Indirect population interaction between two aphid species

We designed an experiment to test whether two species of aphid feeding on d ifferent species of host plant influence each others population dynamics vi a shared parasitoids (apparent competition) or other indirect processes. Pe a aphid (Acyrthosiphon pisum) colonies declined faster towards mid-summer w hen there were nearby colonies of nettle aphid (Microlophium carnosum), tho ugh the significance of the difference (P = 0.06) was just short of the tra ditional 0.05 level. Observations suggested that parasitoids were not respo nsible for this difference, however, and that it was highly likely to be ca used by aphid-specific predators.