The role of interspecific competition in structuring herbivorous
insect communities has been the subject of debate. Current
opinion, which is based on recent reviews of experimental work,
appears to favor competition as a widespread and frequent
process. However, many studies have examined only a few species
pairs within larger multi-species assemblages. In addition, the
frequency of competitive interactions at the population level
has rarely been evaluated in the field at natural herbivore
densities. Thus, the importance of competition as a process
structuring these communities remains unclear. We examined
interspecific competition among 9 species in the seed-feeding
insect guild of wild sunflower. In density manipulation
experiments using typical high densities of herbivores, we found
that only 2 of 18 species pairs interacted competitively within
an inflorescence. Moreover, a population-level experiment found
no evidence of negative effects between species in either of 2
years. When considered together wit