Bottom-up regulation and competition of Aedes aegypti (Diptera: Culicidae) larvae along an urbanization gradient in Puerto Rico: Effects on population performance and vector competence

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Bottom-up regulation and competition of Aedes aegypti (Diptera: Culicidae) larvae along an urbanization gradient in Puerto Rico: Effects on population performance and vector competence Aedes aegypti, is the primary vector of emerging arboviruses causing serious human illnesses including yellow fever, dengue, Zika, and chikungunya. Species population dynamics are related to urbanization and human density as larvae develop in man-made habitats and bloodfeed on humans. Previous studies have independently related urbanization parameters, detrital inputs, and larval competition to some aspects of Ae. aegypti life history (e.g., development time, biomass, fecundity) and vector competence. However, no study has determined how urbanization can influence these ecological interactions in larval habitats, the effect that this can have on Ae. aegypti performance across life stages, generations, and vector competence, nor have used a nutrient stoichiometry approach to do so. Urbanization changes could translate to changes in detritus availability and species competition in larval habitats along a gradient of urbanization which could in turn, influence the susceptibility of Ae. aegypti to dengue infection. The first objective of this proposal is to determine the influence of urbanization on Ae. aegypti larval bottom-up effects and competition in Puerto Rico. The second and third objectives are to assess the influence of urbanization related-detrital inputs and Aedes sp. competition on the species life history across generations and vector competence, respectively. Preliminary data suggests that plant detritus biomass and composition have a significant effect on Ae. aegypti larval and adult biomass. In addition, container water nitrogen (%N) significantly increases with urbanization, that water Carbon:Nitrogen (C:N) is significantly higher in suburban containers, and C:N exhibits a significant relationship with Ae. aegypti larval biomass. The overall hypothesis of this proposal is that urbanization influences detrital inputs and competition in Ae. aegypti larval habitats and that this variation will affect species performance (survival, development rate, and biomass) and dengue vector competence. A combination of field sampling and laboratory experiments will be used to answer the objectives. Sixty larval containers will be sampled across a gradient of urbanization in San Juan, Puerto Rico following a stratified random sampling method with three strata (urban density): low, medium, and high. Incubated containers will simulate larval conditions of each strata with combinations of detrital inputs and species intraspecific and interspecific competition. Aedes aegypti females will be infected with a dengue blood meal to determine virus dissemination and transmission rates. Nutrient analysis (i.e., %C %N, C:N) will be performed on container water, detritus, larvae, and adults from field and laboratory experiments. The results of this research have relevance to vector ecology, vector control strategies, arbovirus diseases, and public health.