Evidence for regular ongoing introductions of mosquito disease vectors into the Galápagos Islands

Abstract

Wildlife on isolated oceanic islands is highly susceptible to the introduction of pathogens. The recent establishment in the Galápagos Islands of the mosquito Culex quinquefasciatus , a vector for diseases such as avian malaria and West Nile fever, is considered a serious risk factor for the archipelago's endemic fauna. Here we present evidence from the monitoring of aeroplanes and genetic analysis that C. quinquefasciatus is regularly introduced via aircraft into the Galápagos Archipelago. Genetic population structure and admixture analysis demonstrates that these mosquitoes breed with, and integrate successfully into, already-established populations of C. quinquefasciatus in the Galápagos, and that there is ongoing movement of mosquitoes between islands. Tourist cruise boats and inter-island boat services are the most likely mechanism for transporting Culex mosquitoes between islands. Such anthropogenic mosquito movements increase the risk of the introduction of mosquito-borne diseases novel to Galápagos and their subsequent widespread dissemination across the archipelago. Failure to implement and maintain measures to prevent the human-assisted transport of mosquitoes to and among the islands could have catastrophic consequences for the endemic wildlife of Galápagos.

West Nile Virus Vector Competency of Culex quinquefasciatus Mosquitoes in the Galápagos Islands

“…Culex quinquefasciatus , a wide-ranging semi-tropical/tropical species associated with fresh water, had been introduced to Galápagos by 1985 and is now established around areas of human habitation. 20,23 Culex quinquefasciatus also has been recently found in uninhabited agricultural or tortoise reserve zones away from human habitation, in the highlands of Santa Cruz, San Cristobal, Isabela, and Floreana islands (Eastwood G, unpublished data). The invasive nature of Cx.…”

“…Recent work detected Culex quinquefasciatus mosquitoes inside aircraft arriving to Galápagos (Baltra airport), and genetic analysis indicates there have been multiple introductions of this mosquito although pathogen infection status was not ascertained. 20 Culex spp. draw particular attention for those monitoring WNV outbreaks because they are the principal vectors; for example, accounting for more than 98% of all mosquito pools positive for WNV in surveillance work in the United States.…”

Understanding Invasive Species in the Galapagos Islands

“…Thus, for example, it was discovered that the black salt-marsh mosquito (Aedes taeniorhynchus)-found in many of the islands-colonized the Galapagos naturally before the arrival of humans (Bataille et al 2009). It has adapted well to the Galapagos and is capable of feeding on reptiles, a characteristic not found among its continental relatives.…”

“…It has adapted well to the Galapagos and is capable of feeding on reptiles, a characteristic not found among its continental relatives. Evidence also exists of the constant introduction of the mosquito Culex quinquefasciatus-a vector for diseases such as avian malaria and West Nile fever-and the ongoing movement of mosquitoes between islands, probably by the transportation mechanisms of tourist cruise ships and interisland boat services (Bataille et al 2009). …”

Corrigendum to: A collaboratively derived environmental research agenda for Galápagos

“…Some invasive species in Galápagos have already been shown to be severely detrimental to native and endemic species, including the parasitic fly Philornis downsi (Kleindorfer and Dudaniec 2016), the black rat (Rattus rattus) (Phillips et al 2012), the feral cat (Felis catus) (Levy et al 2008), and the blackberry (Rubus niveus) (Renteria et al 2012). Their impact mechanisms include parasitism, direct predation, spread of disease (Causton et al 2006;Bataille et al 2009;Deem et al 2012) and competition (Trueman et al 2010). Management of marine invasives (Keith et al 2016) is challenging due to the intrinsic properties of marine ecosystems (Bax et al 2003).…”