Community ecology of container-dwelling invertebrates

Background/Question/Methods

Priority effects can influence the distribution and abundance of species both by preventing colonization of a local habitat and altering the fitness of interacting species.  We conducted a series of field and laboratory studies to determine whether the presence of zooplankton may influence the (1) oviposition behavior and (2) fitness of container-dwelling mosquitoes (primarily Culex restuans).  Field studies were conducted in Trelease Woods, a 28.8 ha deciduous upland forest near Urbana, IL.  The site contains two vernal pools that support a diverse assemblage of zooplankton. Prior work at this site has indicated that artificial containers (< 10 L) are rapidly colonized by zooplankton such as Daphnia pulex, Ceriodaphnia reticulata and copepods, as well as several species of mosquitoes including Culex restuans.  Production of Culex pupae in artificial containers at this site was also shown to be influenced by resource composition.  Based on this prior work, we established a 2x2 factorial experiment in which we altered the presence/absence of zooplankton and the resource base.  We also regularly sampled tires in established tire piles on the site.  Laboratory experiments investigated the outcome of the presence of cladocerans, copepods, and ostracods on the survival, development time and body size of Culex restuans. 

Results/Conclusions

The zooplankton addition treatments in the field study contained multiple species of crustacean zooplankton, including Daphnia pulex, Ceriodaphnia reticulata, cyclopoid copepods, calanoid copepods, and ostricods. Preliminary results from the field experiment indicate that oviposition of Culex restuans was primarily influenced by resources rather than the presence or absence of zooplankton. The community composition within the tire habitats varied depending on the spatial location of the tires in the pile.  In May, tires located at the top of the pile contained only insects and rotifers whereas 80% of samples from tires that were in contact with the ground contained at least one species of crustacean zooplankton. Our ongoing research investigates the potential role of zooplankton in determining the distribution and abundance of container-dwelling mosquitoes, and how that interaction is influenced by proximity to a temporary or permanent source of zooplankton.  Competition with zooplankton has been largely overlooked in the ecology of container-dwelling mosquitoes, many of which serve as vectors for infectious diseases.