Bulletin of Mathematical Biology (2006) 68: 1945–1974 DOI 10.1007/s11538-006-9067-y ORIGINAL ARTICLE A Stochastic Population Dynamics Model for Aedes Aegypti: Formulation and Application to a City with Temperate Climate Marcelo Otero a , Hern ´ an G. Solari a,∗ , Nicol ´ as Schweigmann b a Department of Physics, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina b Department of Genetics and Ecology, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina Received: 6 December 2004 / Accepted: 25 November 2005 / Published online: 11 July 2006 C  Society for Mathematical Biology 2006 Abstract Aedes aegypti is the main vector for dengue and urban yellow fever. It is extended around the world not only in the tropical regions but also beyond them, reaching temperate climates. Because of its importance as a vector of deadly dis- eases, the significance of its distribution in urban areas and the possibility of breed- ing in laboratory facilities, Aedes aegypti is one of the best-known mosquitoes. In this work the biology of Aedes aegypti is incorporated into the framework of a stochastic population dynamics model able to handle seasonal and total extinction as well as endemic situations. The model incorporates explicitly the dependence with temperature. The ecological parameters of the model are tuned to the present populations of Aedes aegypti in Buenos Aires city, which is at the border of the present day geographical distribution in South America. Temperature thresholds for the mosquito survival are computed as a function of average yearly tempera- ture and seasonal variation as well as breeding site availability. The stochastic anal- ysis suggests that the southern limit of Aedes aegypti distribution in South America is close to the 15 ◦ C average yearly isotherm, which accounts for the historical and current distribution better than the traditional criterion of the winter (July) 10 ◦ C isotherm. Keywords Mathematical ecology · Population dynamics · Aedes aegypti · Stochastic model · Temperate climate 1. Introduction Aedes aegypti is mostly a domestic mosquito and the primary vector for urban yel- low fever and dengue. It is the most important vector for dengue in the Americas, ∗ Corresponding author. E-mail address: solari@df.uba.ar (Hern ´ an G. Solari).