Is parasitism of numerically dominant species in macro lepidopteran assemblages independent of their abundance?

Refuge theory proposes that a determinant species richness (and percent parasitism) is the presence of host refuges. Plant structural refuges are good predictors of species richness for endophytic herbivores, but not for exophytic herbivores. For exophytic herbivores other traits such as relative abundance may provide refuge from parasitism. Using unbiased data on both relative abundance and larval parasitism of species in macrotepidopteran assemblages we tested the null hypothesis that percent parasitism was independent of abundance. Numerically subdominant species do not gain refuge from parasitism by persisting at low abundance. Parasitism was not different from what would be expected based on their numbers. Among numerically dominant species there was, nevertheless, a significant positive association between abundance and parasitism rate. However, dominant herbivores displayed high levels of parasitism even in the years when their abundance was low relative to other years. This suggests that dominant species may possess other traits that enhance their susceptibility to parasitoids. (C) 2004 Published by Elsevier GmbH.