The vector ecology of introduced Culex quinquefasciatus populations, and implications for future risk of West Nile virus emergence in the Galápagos archipelago.

G Eastwood,L D Kramer,S J Goodman,A A Cunningham

doi:10.1111/mve.12329

G Eastwood, L D Kramer + Show 2 more

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https://doi.org/10.1111/mve.12329

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Abstract

Culex quinquefasciatus Say (Diptera: Culicidae), an important vector of West Nile virus (WNV) in the U.S.A., was first detected on the Galápagos Islands (Ecuador) in the 1980s. However, little is known of its ecology, distribution or capacity for arbovirus transmission in the Galápagos. We characterize details of lifecycle (including gonotrophic period), temporal abundance, spatial distribution, vector competence and host‐feeding behaviour. Culex quinquefasciatus was detected on five islands of the Galápagos during 2006–2011. A period of 7–14 days was required for egg–adult emergence; water salinity above 5 ppt was demonstrated to hinder larval development. Blood‐meal analysis indicated feeding on reptiles, birds and mammals. Assessment of WNV vector competency of Galápagos C. quinquefasciatus showed a median infectious dose of 7.41 log10 plaque‐forming units per millilitre and evidence of vertical transmission (minimal filial infection rate of 3.7 per 1000 progeny). The distribution of C. quinquefasciatus across the archipelago could be limited by salt intolerance, and its abundance constrained by high temperatures. Feeding behaviour indicates potential to act as a bridge vector for transmission of pathogens across multiple taxa. Vertical transmission is a potential persistence mechanism for WNV on Galápagos. Together, our results can be used for epidemiological assessments of WNV and target vector control, should this pathogen reach the Galápagos Islands.

Highlights

Assessing the ecology of hosts and vectors involved in the transmission cycles of infectious pathogens is key to understanding the potential epidemiology and critical factors affecting disease maintenance and transmission (Institute of Medicine (U.S.) Forum on Microbial Threats, 2008)
A total of 1403 trap-nights were made across 127 sites on nine Galápagos islands, yielding 5241 C. quinquefasciatus
Understanding vector ecology is vital when assessing the potential for vector-borne disease transmission and conducting epidemiological risk assessments (Kilpatrick et al, 2006a)

Summary

Introduction

Assessing the ecology of hosts and vectors involved in the transmission cycles of infectious pathogens is key to understanding the potential epidemiology and critical factors affecting disease maintenance and transmission (Institute of Medicine (U.S.) Forum on Microbial Threats, 2008). Emerging infectious diseases are widely recognized as impacting public and animal health (Jones et al, 2008) They can compromise ecosystem function and threaten species of conservation concern (Daszak et al, 2000; Maillard & Gonzalez, 2006). New or re-emerging pathogens, including those with expanding geographical or host ranges, can adversely affect populations of novel hosts, act as selective forces on host evolution, upset. WNV (a mosquito-borne Flavivirus) can kill reptiles and mammals (Kramer et al, 2008), and following its spread into Central and South America the virus poses a potential threat to the endemic reptilian and avian fauna of Galápagos (Kilpatrick et al, 2006a; Eastwood et al, 2014)

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