Updated distribution maps of predominant Culex mosquitoes across the Americas

Abstract

Background: Estimates of the geographical distribution of Culex mosquitoes in the Americas have been limited to state and provincial levels in the United States and Canada and based on data from the 1980s. Since these estimates were made, there have been many more documented observations of mosquitoes and new methods have been developed for species distribution modeling. Moreover, mosquito distributions are affected by environmental conditions, which have changed since the 1980s. This calls for updated estimates of these distributions to understand the risk of emerging and re-emerging mosquito-borne diseases.

Methods: We used contemporary mosquito data, environmental drivers, and a machine learning ecological niche model to create updated estimates of the geographical range of seven predominant Culex species across North America and South America: Culex erraticus, Culex nigripalpus, Culex pipiens, Culex quinquefasciatus, Culex restuans, Culex salinarius, and Culex tarsalis.

Results: We found that Culex mosquito species differ in their geographical range. Each Culex species is sensitive to both natural and human-influenced environmental factors, especially climate and land cover type. Some prefer urban environments instead of rural ones, and some are limited to tropical or humid areas. Many are found throughout the Central Plains of the USA.

Conclusions: Our updated contemporary Culex distribution maps may be used to assess mosquito-borne disease risk. It is critical to understand the current geographical distributions of these important disease vectors and the key environmental predictors structuring their distributions not only to assess current risk, but also to understand how they will respond to climate change. Since the environmental predictors structuring the geographical distribution of mosquito species varied, we hypothesize that each species may have a different response to climate change.

Keywords: Infectious disease; Mosquito-borne disease; Mosquitoes; Niche model; Species distribution; Vectors.

Fig. 1

The presence data points used in Maxent model development from several data repositories for a Culex pipiens, b Culex restuans, c Culex salinarius, and d Culex tarsalis. The estimated distribution of each species within the USA and Canada is shaded in gray (from Darsie et al. [14]). PHON Public Health of Ontario, WADOH Washington State Department of Health, NEON National Ecological Observatory Network

Fig. 2

The presence data points used in Maxent model development from several data repositories for a Culex erraticus, b Culex nigripalpus, and c Culex quinquefasciatus. The estimated distribution of each species within the USA and Canada is shaded in gray (from Darsie et al. [14]). For abbreviations, see Fig. 1

Fig. 3

Mean geographical distribution maps averaged across the ten bootstrapped models for predominant Culex species in North America, including a Culex pipiens, b Culex restuans, c Culex salinarius, and d Culex tarsalis. The relative habitat suitability is unique to each species based on the Maxent model development

Fig. 4

Mean geographical distribution maps averaged across the ten bootstrapped models for predominant Culex species in North America and South America, including a Culex erraticus, b Culex nigripalpus, and c Culex quinquefasciatus. The relative habitat suitability is unique to each species based on the Maxent model development