Assessing the impact of density dependence in natural larval populations of container inhabiting mosquitoes, Aedes aegypti and Aedes albopictus
Autor(es): Walsh, Rachael Katz
Resumo: Approximately 2.5 billion people in the world are at risk of infection by dengue virus and approximately 50 million infections occur each year. Dengue fever is cause by the mosquito-transmitted dengue virus that produces symptoms along a spectrum, from mild flu-like symptoms to muscle and joint pains to the most severe form, dengue hemorrhagic fever, which can lead to death. The virus is transmitted by the container inhabiting mosquitoes Aedes aegypti and Aedes albopictus. In order to design more efficient approaches for controlling both the disease and the mosquitoes, it is critical to understand the factors that regulate larval density within water-filled containers. Although many studies of intra-specific competition have been conducted using larvae of Ae. aegypti in the laboratory, few studies have been done in the natural environment of Ae. aegypti, and no published studies have critically examined density dependence in natural containers at normal field densities. Additionally, mathematical models that predict Ae. aegypti populations currently lack empirically-based functions for both direct density dependence and delayed density dependence. I performed field experiments in Tapachula, Mexico, where both species of mosquitoes occur naturally, and Raleigh, North Carolina where Ae. albopictus naturally occurs. These experiments were conducted to assess the impact of direct density dependence and delayed density dependence in natural larval populations. In North Carolina, I found a significant impact of delayed density dependence on Ae. albopictus larval survival, larval development time and adult body size in containers with high larval densities. My results indicate that delayed density dependence will have negative impacts on the mosquito population when larval densities reach levels high enough that the larval food consumption rate is higher than the rate of natural food production. In Mexico, results from 2 rainy seasons and 1 dry season showed that direct density dependent factors had a significant impact on larval survival, resulting in an average 16 % decrease in survival from the low density treatment to the high density treatment. The daily probability of a fourth instar pupating was decreased by 29% in the low density treatment compared to the high density treatment. Adults in the low density treatment were significantly larger than adults in the high density treatment. I found significant impacts of interspecific competition with Ae. albopictus on all three parameters. When Ae. albopictus was present, Ae. aegypti experienced a decrease in larval survival and adult body size and an increase in larval development. Delayed density dependence significantly impacted development time and adult body size, but to a lesser degree than direct density dependence. The data collected from these experiments was used to test the accuracy of the current density dependent parameters in SkeeterBuster, an Ae. aegypti population dynamics model.
Palavras-Chave: Entomology
Imprenta: Dissertation Abstracts International, v. 74, n. 07, suppl. B, 2011.
Descritores: Aedes aegypti - Virus ; Aedes aegypti - Dengue ; Aedes aegypti - Public health
Data de publicação: 2011
