Aedes aegypti (Diptera: Culicidae) Longevity and Differential Emergence of Dengue Fever in Two Cities in Sonora, Mexico

Abstract

Dengue virus, primarily transmitted by the Aedes aegypti (L.) mosquito, has rapidly expanded in geographic extent over the past several decades. In some areas, however, dengue fever has not emerged despite established Ae. aegypti populations. The reasons for this are unclear and have sometimes been attributed to socio-economic differences. In 2013 we compared Ae. aegypti adult density and population age structure between two cities in Sonora, Mexico: Hermosillo, which has regular seasonal dengue virus transmission, and Nogales, which has minimal transmission. Larval and pupal abundance was greater in Nogales, and adult density was only higher in Hermosillo during September. Population age structure, however, was consistently older in Hermosillo. This difference in longevity may have been one factor that limited dengue virus transmission in Nogales in 2013, as a smaller proportion of Ae. aegypti females survived past the extrinsic incubation period.

Keywords: Aedes aegypti; Mexico; dengue; longevity.

Fig. 1

Study cities in Sonora, Mexico.

Fig. 2

Comparison of monthly and annual mean meteorological variables between Nogales (blue) and Hermosillo (red). Panels: Monthly mean (A) temperature (°C; solid lines) and minimum and maximum temperature (°C; dotted lines); (B) diurnal temperature range (°C); (C) relative humidity (%; solid lines) and specific humidity (grams of water vapor per kilogram of air; dotted lines); (D) precipitation (mm).

Fig. 3

Distribution of mosquito trapping sites and mean number of Ae. aegypti females collected per trap night from July through September in each city.

Fig. 4

Proportion of total parous Ae. aegypti female adults in each of the three age classes for Nogales (A) and Hermosillo (B).

Fig. 5

Relative risk of potential disease vectors (number of female Ae. aegypti age >14 d) in Hermosillo and Nogales.