Carnivorous Plants and Their Prey

(52). Although M. knabi takes some prey that Wyeomyia would otherwise consume, shredding
increases particulate matter in the fluid which leads to higher bacterial and protozoan populations
and, in turn, the filter-feeding Wyeomyia have access to more of its food sources (52, 62).
Metriocnemus knabi also benefit their carnivorous plant hosts. The midge larvae act much like
shredders in stream ecosystems, breaking larger particles into sizes that can be better used by
neighbors (20). As plant-captured prey is broken into smaller pieces, bacteria have more surface
area to speed digestion. Bacterial action, as well as defecation by insect larvae feeding on various
sized particles, releases nitrogen and other elements into the pitcher fluid allowing the plant to
absorb the nutrients (25, 52, 62, 81). Mites (Sarraceniopus gibsoni) also occupy Sarracenia
pitchers but their role in the infaunal community remains unclear (77).
Darlingtonia-Inquiline Symbioses
While the Sarracenia-Wyeomyia system and its associated inquiline organisms are
relatively well-known, other such mutualistic and commensalistic interactions exist among
carnivorous plant species. A very similar community occurs in the pitchers of Darlingtonia
californica and much like Sarracenia many inquiline organisms, the infauna of Darlingtonia are
facultative but mostly restricted to this specific carnivorous species (29). Midges, for instance,
are found in both Sarracenia and Darlingtonia but Metriocnemus edwardsi favors Darlingtonia
while M. knabi is associated with Sarracenia (29, 38, 80). While both of these pitcher plant
genera have mites in their infauna, mites seem to play a larger role in the Darlingtonia inquiline
community (29, 74, 75). Pitcher-plant slime mites (Sarraceniopus darlingtoniae), M. edwardsi,
and Darlingtonia interact in a manner similar to the Sarracenia-Wyeomyia-M. knabi relationship
(38, 62, 75). Darlingtonia midges act as shredders of plant-captured prey items (75). Breakdown
of prey along with excretion of nitrogenous wastes by M. edwardsi increases the release of
nutrients to the host plant (38, 75). Mites may further degrade prey particles but, as in
Sarracenia, their role in the host nitrogen budget is poorly understood (29, 75). It is possible that
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