MOSQUITO LARVAE (CULISETA-LONGIAREOLATA) PREY UPON AND COMPETE WITH TOAD TADPOLES (BUFO-VIRIDIS)

1. We tested experimentally for interactions between mosquito larvae, Culiseta longiareolata, and green toad immatures, Bufo viridis, the tw o most abundant macrospecies of temporary pools in the Negev Desert, I srael. Since both appear to feed largely on periphyton, and since they co-occur in extremely high densities, competition for food may occur. 2. In artificial outdoor pools, we followed the fate of first-instar Culiseta larvae (50 per litre) and early-stage tadpoles (5 per litre) in the presence or absence of the other species over 1 month. These de nsities were well within the range of densities found in natural pools . We replicated each treatment five times. 3. Survival of neither spec ies was affected by the other species. However, time to pupation in Cu liseta was longer and pupal size was smaller in the presence of Bufo t adpoles. Similarly, tadpole weights were lower and the percentage of B ufo reaching metamorphosis by the end of the experiment was lower in t he presence of Culiseta larvae. We attribute these mutual negative eff ects upon each other to interspecific competition. 4. Late-stage Culis eta larvae also preyed upon Bufo hatchlings in both field enclosure an d laboratory experiments. This is the first demonstration of a mosquit o larva as a natural predator of a vertebrate. The high predation rate s indicate that Culiseta affects Bufo populations significantly via pr edation in nature. 5. These two surprising roles of a mosquito larva-a competitor and predator of a vertebrate-emphasize that how communitie s are organized may be misinterpreted by presuming particular roles fo r species based on taxonomic affiliation.