Global Impact of Mosquito Biodiversity, Human Vector-Borne Diseases and Environmental Change

Abstract

More than 3,400 species of mosquito have been recorded worldwide. They include 37 genera, all within a single family, the Culicidae, itself divided into 3 sub-families, Toxorhynchitinae, Anophelinae, and Culicinae. They occur in tropical and temperate zones, even above the Arctic Circle but are absent in the Antarctic. They are found as high as 6,000 m (above sea level) in mountainous regions and as deep as 1,250 m (below sea level) in caves and mines (Lane & Crosskey, 1993). If there is obviously an academic interest in the description and understanding of mosquito biodiversity, its study is also a major issue because of the risk associated with invasive species and the emergence and spread of vector-borne diseases. The efficiency, speed and reach of modern transport networks put indeed people at risk from the emergence of new strains of familiar diseases or completely new diseases (Guimera et al., 2005). The global growth of economic activity, tourism, and human migration is leading to ever more cases of the movement of both diseases vectors and the pathogens they carry (Tatem et al., 2006b), increasing at the same time the biodiversity of mosquitoes around the world. In the current context of global warming, the expansion of areas suitable for the major disease vectors is becoming a threat and even a reality for some regions with several species being classified as invasive. To temperate this point, it is important to mention that among all mosquito species recorded, only 10% are regarded as efficient vectors of infectious agents having a considerable impact on human welfare and health. However, this small fraction is responsible for some of the worst scourges of humankind and the most important vectors belong essentially to three genera including Anopheles, Aedes, and Culex among which some species have been quite successful of wide-scale invasions. An invasive species is defined as a species having a great impact on its new environment and spreading with measurable growth and distance dispersed (Daehler, 2001). Three major biological characteristics are found among the most invasive mosquito species, their close association with humans, egg resistance to desiccation (genus Aedes), and small larval habitats such as a wide variety of water holding containers among which man-made ones