Liaisons dangereuses: cross-border gene flow and dispersal of insecticide resistance-associated genes in the mosquito Aedes aegypti from Brazil and French Guiana

Abstract

BACKGROUND In recent years, South America has suffered the burden of continuous high impact outbreaks of dengue, chikungunya and Zika. Aedes aegypti is the main mosquito vector of these arboviruses and its control is the only solution to reduce transmission.OBJECTIVES In order to improve vector control it is essential to study mosquito population genetics in order to better estimate the population structures and the geneflow among them. METHODS We have analysed microsatellites and knockdown resistance (kdr) mutations from a trans-border region in Amazonia between the state of Amapá (Brazil) and French Guiana (overseas territory of France), to provide further knowledge on these issues. These two countries have followed distinct vector control policies since last century. For population genetic analyses we evaluated variability in 13 well-established microsatellites loci in Ae. aegypti from French Guiana (Saint Georges and Cayenne) and Brazil (Oiapoque and Macapá). The occurrence and frequency of kdr mutations in these same populations were accessed by TaqMan genotype assays for the sites 1016 (Val/Ile) and 1534 (Phe/Cys). FINDINGS We have detected high levels of gene flow between the closest cross-border samples of Saint-Georges and Oiapoque. These results suggest one common origin of re-colonisation for the populations of French Guiana and Oiapoque in Brazil, and a different source for Macapá, more similar to the other northern Brazilian populations. Genotyping of the kdr mutations revealed distinct patterns for Cayenne and Macapá associated with their different insecticide use history, and an admixture zone between these two patterns in Saint Georges and Oiapoque, in accordance with population genetic results. MAIN CONCLUSIONSThe present study highlights the need for regional-local vector surveillance and transnational collaboration between neighboring countries to assess the impact of implemented vector control strategies, promote timely actions and develop preparedness plans.

Vector Competence of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus from Brazil and New Caledonia for Three Zika Virus Lineages

“…Genes controlling resistance to insecticides can have pleiotropic effects and result in changes in the insect’s vector capacity, such as longevity, behavior, and vector competence [ 58 ]. The Brazilian Aedes mosquito populations tested here differed considerably in terms of their resistance to insecticides such as Temephos and Deltramethrin which were employed in the National Dengue Control Program [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 ]. The Natal and Rio de Janeiro Ae.…”

Spatiotemporal multiple insecticide resistance in Aedes aegypti populations in French Guiana: need for alternative vector control

“…However, low gene flow and local selection of resistance should have shaped different resistance patterns amongst populations. (22,23) In contrast, malathion and temephos were the mainstay of vector and pest mosquito control in the central littoral strip, where malaria is a rare event for the last 40 years.…”

“…The primary cause is most likely genetic structure among populations of French Guiana, inducing a local selection of resistance and therefore the development of different patterns. (22,23) These selective pressures with either pyrethroids or DDT are not easy to unravel. However, the fact that Saint Laurent du Maroni and Saint Georges de l'Oyapock have been subjected to both malaria vector control and Aedes control must be noted.…”

Differential attraction in mosquito–human interactions and implications for disease control

“…While vector management has proved to be one of the most effective ways to reduce disease transmission, control methods that are successful today may soon lose their efficacy owing to rapidly evolving mosquito populations [4]. The spread of resistance to insecticides is a concern in many parts of the world [5][6][7], especially pyrethroid resistance as pyrethroids are the major class of insecticides used in WHO-recommended LLINs [8]. Evidence of behavioural changes in mosquito feeding in response to LLINs and IRS, termed 'behavioural resistance', has also been reported [9], with several examples of mosquito populations becoming exophagic (i.e.…”