Predator-prey interactions and community structure: chironomids, mosquitoes and copepods in Heliconia imbricata...

Evidence from both field observations and experimental work indicates that predation by larvae of a midge, Pentaneura n. sp. (Chironomidae), causes the low densities of mosquito larvae (Culicidae) found in the water filled bracts of Heliconia imbricata (Musaceae), microhabitats typically colonized by mosquitoes. This predation affects 2 species of mosquitoes, Wyeomyia pseudopecten, a resident species, and Trichoprosopon digitatum, a non-resident species. Predation keeps resident mosquito densities low while completely excluding the nonresident mosquito from the habitat. Both these effects of predation depend on the presence of an abundant alternative prey, an undescribed species of harpacticoid copepod found in the bracts. These copepod prey sustain chironomids when resident mosquito densities are low, permiting predator densities to remain high enough to exclude the non-resident mosquito. I discuss the evolutionary and ecological implications of predation structuring communities.