Urbanization Increases Aedes albopictus Larval Habitats and Accelerates Mosquito Development and Survivorship

Abstract

Introduction

Aedes albopictus is a very invasive and aggressive insect vector that causes outbreaks of dengue fever, chikungunya disease, and yellow fever in many countries. Vector ecology and disease epidemiology are strongly affected by environmental changes. Urbanization is a worldwide trend and is one of the most ecologically modifying phenomena. The purpose of this study is to determine how environmental changes due to urbanization affect the ecology of Aedes albopictus.

Methods

Aquatic habitats and Aedes albopictus larval population surveys were conducted from May to November 2013 in three areas representing rural, suburban, and urban settings in Guangzhou, China. Ae. albopictus adults were collected monthly using BG-Sentinel traps. Ae. albopictus larva and adult life-table experiments were conducted with 20 replicates in each of the three study areas.

Results

The urban area had the highest and the rural area had the lowest number of aquatic habitats that tested positive for Ae. albopictus larvae. Densities in the larval stages varied among the areas, but the urban area had almost two-fold higher densities in pupae and three-fold higher in adult populations compared with the suburban and rural areas. Larvae developed faster and the adult emergence rate was higher in the urban area than in suburban and rural areas. The survival time of adult mosquitoes was also longer in the urban area than it was in suburban and rural areas. Study regions, surface area, water depth, water clearance, surface type, and canopy coverage were important factors associated with the presence of Ae. albopictus larvae.

Conclusions

Urbanization substantially increased the density, larval development rate, and adult survival time of Ae. albopictus, which in turn potentially increased the vector capacity, and therefore, disease transmissibility. Mosquito ecology and its correlation with dengue virus transmission should be compared in different environmental settings.

Author Summary

Aedes albopictus has expanded its ecological habitat range throughout the world. Although Ae. albopictus was previously considered a rural vector, this species has adapted well to suburban and urban environments, and it has become the most important and sometimes the sole vector of dengue virus transmission in urban areas. Dengue is a vector-borne disease that has become a severe global public health problem during the last decade. We explored the effect of ecology in different ecological settings (urban, suburban, and rural) on Ae. albopictus larval habitat and mosquito development in Guangzhou, where recently dengue has caused serious public health concerns. The environmental changes caused by urbanization had a significant impact on the ecology of Ae. albopictus. Compared with rural and suburban areas, urban areas had more Ae. albopictus larval habitats, shorter larval development time, higher adult emergence rate, and longer lifespan. These results imply that urbanization significantly increases the potential for dengue outbreaks. Because urbanization is a global trend resulting from economic development, the elucidation of Ae. albopictus adaptation to different environments in China also reveals the potential for this important vector to colonize other parts of the world.