COS 43-5
Effects of density dependence and competition on development and fecundity of larval mosquitoes
Species which undergo ontogenetic niche shifts during their life cycle can produce strong, ecosystem-coupling interactions which have been termed trans-boundary ecosystem effects. Mosquitoes are a paradigmatic example of a species that undergoes such a shift as it moves from the (aquatic) larval to (terrestrial) adult life stage. We propose that this trans-boundary coupling occurs in mosquitoes due to interactions at the larval stage which affect the resulting adult community diversity. Using laboratory microcosms with an additive and substitutive experimental design, we explored the effects of density and intra- and interspecific competition on the survival, development time, and fecundity (using adult body size as a proxy) of three medically important, co-occurring mosquito species: Aedes albopictus, Ae. aegypti, and Culex quinquefasciatus. We expected than an increase in density and/or the number of competitors would result in decreased survival, increased development time, and decreased fecundity across all species. With data partitioned by species, we then ran an ANOVA on linear fixed-effects models to determine which predictors (density, competitor identity) made significant contributions to the variance in each of our response variables (survival, development time, fecundity).
Results/Conclusions
The only significant term from the linear model for Cx. quinquefasciatus was density (p<0.001). Increased treatment density resulted in decreased development time regardless of which competitors were present. Significant terms from the Ae. albopictus model include density (p=0.005), presence of Culex as a competitor (p=0.024), and the interaction between these two terms (density*Culex, p=0.009). Increasing density resulted in decreased development times, while the presence of Culex resulted in increased development times, which was exacerbated at higher densities. For the Ae. aegypti model, the significant terms included density (p=0.040), presence of Ae. albopictus as a competitor (p=0.016), and the interaction between density and the presence of Culex as a competitor (density*Culex, p=0.012). While all three significant predictors resulted in increased development times, the interaction between density and Culex presence suggest that Culex only has a marked effect on development time at higher densities. Data from this experiment will be used to parameterize a dynamical systems model that will explore the effects of larval interactions on adult mosquito community composition, with applications to vector-borne disease ecology.