Summary 1. Females should choose to oviposit in habitats where risk of predation and competition are low. The ovipositional responses of a mosquito, Culiseta longiareolata, to a predator and to species sharing the same trophic level as this mosquito (controphic species) were assessed experimentally in outdoor artificial pools. 2. The predator, larval Anax imperator, which strongly reduced larval C. longiareolata survival, resulted in a 52% reduction of C. longiareolata egg rafts. The controphic species (primarily Daphnia magna), which had a small but statistically significant negative effect on the survival of C. longiareolata larvae, did not have a statistically significant influence on the number of egg rafts. 3. Laboratory trials indicated that only a small fraction of the reduced number of egg rafts seen in predator pools may be due to consumption of the egg rafts by A. imperator. 4. The experimental evidence indicates that the reduced number of C. longiareolata egg rafts found in the presence of A. imperator is due largely to oviposition habitat selection, i.e. C. longiareolata females choose pools with low risk of predation for their offspring.

We investigated the bacterial diversity of microbial communities in water-filled, human-made and natural container habitats of the mosquitoes Aedes aegypti and Aedes albopictus in suburban landscapes of New Orleans, Louisiana in 2003. We collected water samples from three classes of containers, including tires (n=12), cemetery urns (n=23), and miscellaneous containers that included two tree holes (n=19). Total genomic DNA was extracted from water samples, and 16S ribosomal DNA fragments (operational taxonomic units, OTUs) were amplified by PCR and separated by denaturing gradient gel electrophoresis (DGGE). The bacterial communities in containers represented diverse DGGE-DNA banding patterns that were not related to the class of container or to the local spatial distribution of containers. Mean richness and evenness of OTUs were highest in water samples from tires. Bacterial phylotypes were identified by comparative sequence analysis of 90 16S rDNA DGGE band amplicons. The majority of sequences were placed in five major taxa: Alpha-, Beta-and Gammaproteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and an unclassified group; Proteobacteria and Bacteroidetes were the predominant heterotrophic bacteria in containers. The bacterial communities in human-made containers consisted mainly of undescribed species, and a phylogenetic analysis based on 16S rRNA sequences suggested

Species sharing the same trophic level as mosquito larvae (hereafter, controphic species) may have complex effects on mosquitoes by sharing both predators and food resources. We conducted an outdoor artificial pool experiment to assess the individual and interactive effects of a predator (Anax imperator) and controphic species (primarily Daphnia magna) on larval populations of two common mosquitoes, Culex pipiens and Culiseta longiareolata. Controphic species did not significantly affect survival to pupation of C. pipiens but did increase time to metamorphosis and reduce size at metamorphosis. Culex pipiens and D. magna, both primarily filter feeders, probably compete for food resources. Controphic species caused a small reduction (21.9%) in C. longiareolata survival, an unexpected result given that C. longiareolata larvae are thought to be primarily periphyton grazers while D. magna is a filter feeder. Controphic species did not affect C. longiareolata time to, or size at, pupation. Anax imperator reduced C. longiareolata survival to pupation (78%) and size at pupation (11.5%) while increasing development time in males only (11.3%). Anax imperator caused a smaller (32.4%), but statistically significant, reduction in the number of C. pipiens surviving to the pupal stage but did not significantly affect size at or time to pupation. The predator did not reduce controphic species densities, and controphic species did not result in increased predator growth. We predicted that controphic species, by serving as competitors, would result in fewer C. pipiens surviving to pupation in the absence of predators. In the presence of the predator, the negative competitive effect of controphic species would be attenuated by the positive effect of serving as alternative prey. Our results followed this pattern although the predator × controphic species interaction was not statistically significant (P = 0.157). Because previous studies showed that D. magna did not affect predation rates by A. imperator on C. longiareolata larvae, and because controphic species did not have a strong competitive effect, we did not predict and did not find a predator × controphic species interactive effect.