Pitcher plants (Sarracenia purpurea) in eastern Canadian peatlands. Ecology and conservation of the invertebrate inquilines

The relationship between S. purpurea and its inquilines in northeastern North America is reviewed. Wyeomyia smithii, Metriocnemus knabi and Blaesoxipha fletcheri dominate the insect community of S. purpurea. All 3 are detritivores and feed on the arthropod prey attracted to the pitcher plant. They coexist by partitioning the habitat and food resource spatially. W. smithii lives in the water column of the pitcher and feeds by filtering microorganisms (bacteria and protozoa) from the water. M. knabi feeds on the dead organisms that have accumulated at the bottom of the pitcher. B. fletcheri feeds at the surface on floating prey items that have drowned in the pitcher fluid. The action of these inquilines apparently speeds up the release of nutrients (mainly nitrogen and carbon dioxide) to the plant, and in turn the plant removes potentially toxic metabolic wastes (ammonia, CO2) from the water and infuses oxygen. Pitcher plant habitats, mainly Sphagnum bogs, are at risk in some areas of the region, particularly in the more populated zones in the south, to urbanization, agriculture, aforestation, and peat harvest. However, this represents only a small part of the total available peatland habitat in Canada..