How does overall population density and temperature affect the fecundity of female Aedes aegypti mosquitoes?

Lindsey Jones, a student from Albany State University, worked with Michelle Evans in the lab of Dr. Courtney Murdock to look at fecundity of a mosquito vector species.

Abstract:  Dynamics of mosquito-borne diseases such as Zika, yellow fever, chikungunya, and dengue depend on the ecology of both the disease and vector. Past studies have shown that both abiotic and biotic factors, such as temperature and population density, influence mosquito population dynamics, but the relationship of their interaction is unknown. Here, we explore how abiotic and biotic factors interact to influence life history traits of the Aedes aegypti mosquito. Specifically, we explored how intra- and inter-specific population densities and environmental temperature affect the fecundity of female Ae. aegypti mosquitoes. We used a factorial design of twelve density and four temperature treatments, for a total of 48 treatments in this experiment. We reared 1st instar Ae. aegypti and An. stephensi larvae to adulthood in 250 mL RO water with 0.1 g Tetramin fish food in mason jars in Percival incubators. Following emergence, adult female Ae. aegypti mosquitoes were collected, blood fed, and individually placed into centrifuge tubes at 28oC. We collected and recorded the number of eggs laid for each individual emerging per day to estimate the mosquito per capita growth rate. We found that Ae. aegypti fecundity increases with decreasing temperatures. We also found that fecundity decreases as the overall population density increases, along with the density of the competitor. As an interaction, temperature, overall density, and density of the competitor, affected fecundity, suggesting the effects of biotic factors could quantitatively and qualitatively vary across different thermal environments. We found that the population growth rate of Ae. aegypti decreased with increasing density and decreasing temperatures. These results highlight the complexity of how environmental factors can shape disease transmission.

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