Distribution of insecticide resistance and molecular mechanisms involved in the West Nile vector Culex pipiens in Morocco

Abstract

BACKGROUND Mosquitoes of the Culex pipiens complex are the vectors of several arboviruses and are thus subjected to insecticide control worldwide. However, overuse of insecticides selects for resistance. While assessing the resistance status of the vectors is required for effective and sustainable disease control, resistance has so far only been sparsely studied in Morocco. In this study, we establish a first countrywide assessment of the levels of resistance to various insecticides and the potential responsible mechanisms involved. Cx. pipiens larvae were collected from natural populations of five regions of Morocco, and their taxonomic status was determined (molecular forms). The level of their susceptibility to insecticides was assessed by single‐diagnostic‐dose bioassays. Molecular identification of known resistance alleles was investigated to determine the frequency of target‐site mutations. RESULTS This study confirms that Moroccan populations are an interbreeding mix of pipiens and molestus forms, with large gene flow for the resistance alleles. We also found that Cx. pipiens mosquitoes are resistant to all insecticide families, all over Morocco: resistance is high for insecticides used in mosquito control, but also present for other pesticides. Resistance alleles are similarly more frequent for mosquito control insecticides. However, their distribution is heterogeneous in the five regions, with significant genetic differentiation between populations, revealing the crucial role of local insecticide treatment practices. CONCLUSION This study provides reference countrywide data that highlight the need for further research to refine the distribution of resistance in Morocco and to understand the role of agriculture/urban residuals in its spread. © 2020 Society of Chemical Industry

Türkiye'nin Orta ve Doğu Karadeniz Bölgesi tarımsal ve yapay alanlarda yayılım gösteren Culex pipiens L., 1758 (Diptera: Culicidae)’te kdr ve ace-1 mutasyon varyasyonlarının izlenmesi ve dağılımı

“…For all AChE mutations, studied populations showed tendencies towards an excess of heterozygotes. Similar results were obtained by some authors (Taskin et al, 2016;Arich et al, 2021).…”

“…pipiens populations (Alout et al, 2007b;Alout et al, 2009). Although G119S mutation were described around the world, F290V was rarely recorded in Mediterranean countries such as Greece, Morocco, Tunisia, and Türkiye (Alout et al, 2007b;Kioulous et al, 2014;Ben Cheikh et al, 2009;Taskin et al, 2016;Arich et al, 2021). Two different codon combinations were identified at the F290 mutation point causing organophosphate/carbamate resistance in this study, and these combinations were TTT codon (wild type) and GTT codon (encoding valine).…”

No association between habitat, autogeny and genetics in Moroccan Culex pipiens populations

“…Morocco presents a most suitable opportunity to address this question: similar to the situation in Tunisia and Algeria, a previous analysis showed that both alleles of the CQ11 marker segregate in natural populations, with many heterozygotes [34]. In the present study, we took advantage of this situation to assess the association between autogeny, revealed through ovarian dissection, and CQ11 genotypes.…”

“…As in previous studies [34,44,45], the genotype at the CQ11 locus was used to understand the character of Moroccan populations (e.g. pipiens-like, molestus-like, intermediate or harboring both discrete types).…”

Mosquito Vectors (Diptera: Culicidae) and Mosquito-Borne Diseases in North Africa

“…In Morocco, Arich et al found that Cx. pipiens forms pipiens and molestus were resistant to most common insecticide families used in mosquito control as well as in agriculture or urban residuals, all over Morocco [ 197 ]. Further studies are needed to elucidate the reality of insecticide resistance of mosquito vector species in North Africa, in order to promote integrated control strategies.…”