1014F-kdr and G119S ace-1 mutations conferring insecticide resistance detected in the Culex pipiens complex in Morocco

Abstract

Culex pipiens mosquitoes are competent vectors for several arboviruses worldwide. In Morocco, they specially transmit West Nile virus (VWN) and Rift Valley fever virus (VFVR) (Bkhache et al., 2018). The repeated treatment with chemical insecticides in areas highly exposed to the mosquitoes nuisance leads to the resistance development. The lack of data on resistance mechanisms in Morocco allow us to evaluate both of the levels of DDT resistance accompanied by the frequency of the mutated gene associated L1014F kdr, and the levels of bendiocarb resistance accompanied by the frequency of the mutated gene associated G119S ace-1R respectively in both regions Benslimane and Mohammedia. MethodsMosquito larvae were collected from two different breeding sites: El Jazeera from Benslimane region and Ouled Hamimoun from Mohammedia region. Adults were reared from collected immature stages in the laboratory at 28 {+/-} 1 {degrees}C with 80% relative humidity. Standard WHO insecticide susceptibility tests were conducted on adult females emerged from collected larvae. Specimens were identified as Culex pipiens following morphological criteria under microscope using Culicidae of African Mediterranean software (Giner et al., 1999). Identified mosquitoes were then tested for the presence of the L1014F kdr and G119S ace-1R mutations using PCR assay. ResultsOur results showed that all the tested populations have a resistance to DDT 4% with a mortality rate ranging from 2% to 74%, and to bendiocarb 0.1% with a mortality rate ranging from 32% to 74%. In plus, 30 individuals from each region were screened for both mutations L1014F kdr and G119S ace-1R. The molecular identification of survivor genes shows the presence of L1014F kdr mutation in both region with different frequencies. The allelic frequency was low with 0.15% in Mohammedia region and complete absence of resistant homozygotes alleles 1014F/1014F in the same region, but average with 0.65% in Benslimane region. However, the G119S ace-1R mutation was absent in both regions. These results are consistent with those published by Aboulfadl et al. (2020) on the same populations and who found that the resistance of Mohammedia populations is completely metabolic and based only on cytochrome P450 enzymes while that of Benslimane populations is partially metabolic. ConclusionThe study highlights the implication of L1014F kdr mutation in DDT resistance and G119S ace-1R mutation in bendiocarb resistance in Cx. pipiens populations from two regions in Morocco.