In:
BioMed Research International, Hindawi Limited, Vol. 2018 ( 2018-07-11), p. 1-10
Abstract:
Background . Several mutations in voltage gated sodium channel ( N a V ) have been identified in Aedes aegypti populations worldwide. However, only few are related to knockdown resistance to pyrethroids, most of which with variations in the 1016 and 1534 N a V sites. In Brazil, at least two Na V alleles are known: N a V R1, with a substitution in the 1534 (1016 Val + + 1534 Ile kdr ) and N a V R2, with substitutions in both 1016 and sites (1016Il e k d r + 1534Cys kdr ). There is also the duplication in the Na V gene, with one copy carrying the substitution Ile1011Met, although its effects on pyrethroid resistance remain to be clarified. Our goals in this study were (1) to determine the role of each kdr N a V allele and the duplication on pyrethroid resistance and (2) to screen the frequency of the kdr alleles in 27 several natural Ae. aegypti populations from the metropolitan region of Rio de Janeiro. Methods . Pyrethroid resistance was evaluated by a knockdown time ( Kd T) assay, an adaptation of the WHO test tubes with paper impregnated with deltamethrin. We used laboratory-selected Ae. aegypti lineages: R1R1 and R2R2 (homozygous for the kdr N a V R1 and N a V R2 alleles, respectively), Dup (with duplication in the Na V gene), Rockefeller (the susceptibility reference control), and F1 hybrids among them. Genotyping of both 1016 and 1534 N a V sites was performed in 811 Ae. aegypti sampled from 27 localities from Rio de Janeiro (17), Niterói (6) and Nova Iguaçu (4) cities, Rio de Janeiro State, Brazil, with a TaqMan real time PCR approach. Results . The laboratory lineages R1R1, R2R2, and R1R2 were the only ones that needed more than 60 minutes to knock down all the insects exposed to the pyrethroid, being the Kd T R2R2 〉 R1R2 〉 R1R1, corroborating the recessive nature of the kdr mutations. Frequency of kdr alleles N a V R1 and N a V R2 in field-caught mosquitoes varied from 0 to 52% and 43 to 86%, respectively, evidencing high levels of “resistant genotypes” (R1R1, R1R2, and R2R2), which together summed 60 to 100% in Ae. aegypti populations from Rio de Janeiro. Conclusions . The N a V R1 and N a V R2 kdr alleles confer resistance to the pyrethroid deltamethrin in homozygotes and R1R2 heterozygotes, being the R2R2 most resistant genotype. The allele containing duplication in the N a V gene, with a mutation in the 1011 site, did not confer resistance under the tested conditions. The frequencies of the “resistant genotypes” are elevated in Ae. aegypti natural populations from Rio de Janeiro.
Type of Medium:
Online Resource
ISSN:
2314-6133
,
2314-6141
DOI:
10.1155/2018/2410819
Language:
English
Publisher:
Hindawi Limited
Publication Date:
2018
detail.hit.zdb_id:
2698540-8
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