Functional ecology of the ciliate Glaucomides bromelicola, and comparison with the sympatric species Bromeliothrix metopoides.

We investigated the ecology and life strategy of Glaucomides bromelicola (family Bromeliophryidae), a very common ciliate in the reservoirs (tanks) of bromeliads, assessing its response to food quality and quantity and pH. Further, we conducted competition experiments with the frequently coexisting species Bromeliothrix metopoides (family Colpodidae). In contrast to B. metopoides and many other colpodean ciliates, G. bromelicola does not form resting cysts, which jeopardizes this ciliate when its small aquatic habitats dry out. Both species form bactivorous microstomes and flagellate-feeding macrostomes. However, only G. bromelicola has a low feeding threshold and is able to adapt to different protist food. The higher affinity to the local bacterial and flagellate food renders it the superior competitor relative to B. metopoides. Continuous encystment and excystment of the latter may enable stable coexistence of both species in their natural habitat. Both are tolerant to a wide range of pH (4-9). These ciliates appear to be limited to tank bromeliads because they either lack resting cysts and vectors for long distance dispersal (G. bromelicola) and/or have highly specific food requirements (primarily B. metopoides).

Vertical oviposition and Lambornella clarki (Ciliophora: Tetrahymenidae) dispersal by Aedes sierrensis (Diptera: Culicidae) in California.

Vertical stratification of treeholes used by mosquitoes may reflect resource quality or result from interspecific competition. Mosquitoes able to monopolize treeholes with optimal resources may be over-represented in the community. Aedes sierrensis, which is well adapted for the Mediterranean climate of California, has evolved in the absence of interspecific competition, so oviposition should reflect resource quality to a large extent. Artificial oviposition traps mounted at four canopy heights facing north or south on trees in a mixed-oak forest at four elevations of the Pacific Coastal Range were used to assess vertical ovipositional preferences by the western treehole mosquito. Natural dispersal of the ciliated protozoan parasite Lambornella clarki was similarly monitored. Gravid Ae. sierrensis showed no vertical stratification during egg laying in traps. Lambornella clarki were naturally dispersed at relatively low frequency into traps and persisted unless eliminated by larval predation. Aedes sierrensis is not currently constrained into occupying a subset of treeholes. However, invasion of its native range by competitive species may alter oviposition patterns.