Molecular Analysis of Targeted Insecticide Resistance Gene Mutations in field Aedes Aegypti and Culex Quinquefasciatus Mosquito Vectors of Arboviruses from Saudi Arabia

Abstract

Background In absence of effective and safe vaccines or drugs against mosquito-borne arboviral diseases (such as dengue, Zika and Rift Valley and West Nile), there have been an increasing pattern of insecticide use against the mosquito vectors of these diseases in integrated vector management (IVM) programs in Saudi Arabia. However, the efficacy of IVM programmes is threatened by the development of insecticide resistance in vectors. Gene mutations on target sites can be a valuable reference to the status of insecticide resistance. Jeddah, a global commercial and major port-of-entry city, is bearing the most (> 70%) dengue disease burden and the population of the dengue vector Aedes aegypti in Saudi Arabia. Culex quinquefasciatus is a second example as one of the major arboviral vectors in the region and a proven vector of Rift Valley fever and wide-spread in Jeddah and the rest of the western region of Saudi Arabia. However, the status of insecticide resistance and targeted site mutations on the responsible genes are not fully characterized.Methods We randomly sampled both mosquito species, Ae. aegypti and Cx. quinquefasciatus across Jeddah by daily mosquito surveillance in 2016 to detect the resistance-associated target site mutations on the voltage gated sodium channel (VGSC) and acetylcholinesterase 1 (ace-1) genes.Results Our findings showed that Ae. aegypti resistance-associated VGSC gene mutations revealed polymorphic mutations on the 989 (allele frequency = 65.91%), 1016 (allele frequency = 65.91%), and 1534 (allele frequency = 52.27%) sites. Additionally, we documented two types of introns between exons 20 and 21, however, the I1011M point mutation was undetected. Linkage disequilibrium associations were shown between V1016G with S989P, V1016G with F1534, and V1016G with type A intron. Furthermore, no mutation on ace-1 was identified in Ae. aegypti. In Cx. quinquefasciatus, homozygous L1014F/L1014F (95.23%) on the VGSC and heterozygous G119/G119S (100%) on ace-1 were widely distributed in the samples studied.Conclusions To the best of our knowledge, this is the first record of the intron types between exons 20 and 21 on VGSC of Ae. aegypti populations, and the first report of insecticide resistance gene mutation being present in field caught Cx. quinquefasciatus in Jeddah, Saudi Arabia. High prevalence of insecticide resistance gene mutations in local primary mosquito vector species, implies that the local Ae. aegypti mosquitoes are resistant to both pyrethroid and DDT, while the resistance to all four insecticide groups may possessed in Cx. quinquefasciatus populations. Our findings alert the urgent need to carry out a comprehensive insecticide resistance gene mutation surveillance and monitoring to guide sustained and effective IVM planning and innovative guidelines in local predominate mosquito populations and mosquito-borne disease control and elimination in Saudi Arabia.

Molecular analysis of targeted insecticide resistance gene mutations in field Aedes aegypti and Culex quinquefasciatus mosquito vectors of arboviruses from Saudi Arabia

“…aegypti, and 10 strains of Culex avivirus (CxFV) in pools of Cx. quinquefasciatus population from Jeddah [16]. Meanwhile, the two species suffered from extensive and long-time insecticide exposure for routine mosquito control operations using larvicides spraying of their natural breeding habitats and indoor residual spraying (IRS) using adulticides, resulting in developing of insecticide resistance, which subsequently reduced the e cacy of insecticide treatments [7,9,15,17].…”

Molecular analysis of targeted insecticide resistance gene mutations in field Aedes aegypti and Culex quinquefasciatus mosquito vectors of arboviruses from Saudi Arabia

“…1, and a map was generated using ArcGIS 10.1 ArcMap software (ESRI, Redlands, CA, USA). Taxonomic identi cation and ecological information on the analyzed samples are mentioned elsewhere[41].DNA extraction and target gene mutation sequencingFor DNA extraction, individual mosquito samples, each was homogenized in a mixer mill (Jingxin, Shanghai, China) in 250 μl of ATL (Qiagen, Hilden, Germany) and 20 μl of proteinase K (Qiagen, Hilden, Germany) with two 3-mm steel balls were added to each tube. The homogenates were incubated at 56 °C overnight in an oscillating thermo-block.…”