Abstract
Background: Although there is a vast literature concerning insecticide resistance (IR) in Plasmodium vectors from African and Asian continents, similar studies with Neotropical anophelines are scares. Herein we evaluated the IR profile of Anopheles albitarsis s.s. of a laboratory colony and a natural population collected around a rice plantation field. The laboratory colony is original from a collection performed in this same region more than two decades ago. Methods: We collected An. albitarsis females while resting after blood feeding, around rice field plantations in Massaranduba, SC, Brazil. These females laid their eggs in the laboratory, and the larvae were raised in parallel with our lab colony. To be sure about the field samples’ taxonomic status, we amplified and sequenced the mitochondrial COI gene of a sampling of field captured mosquitoes. We performed a simplified knockdown test with larvae exposed to permethrin and deltamethrin and submitted adult females to a WHO like tube test with the pyrethroids permethrin, deltamethrin, and etofenprox, in addition to the organophosphate malathion. A segment of the voltage-gated sodium channel gene (NaV) was amplified and cloned. Based on the observed sequences, we developed a TaqMan genotyping assay for the variation L1014F and calculated the genotypic and allelic frequencies concerning this SNP in the field population.Results: The COI analyses confirmed the taxonomic status of An. albitarsis s.s in laboratory and field samples. The field population was resistant to pyrethroids but not to malathion. We observed the substitutions L1019R, F1020S, and the classical kdr L1014F in the NaV gene. This classical kdr allele was present under low frequencies in the overall field population (2%), although more frequent in pyrethroid-resistant insects.Conclusions: The An. albitarsis s.s. population from Massaranduba was resistant to pyrethroids, likely due to selection pressure exerted by agrochemical pesticides. We registered the classical kdr mutation in a Brazilian Anopheles species for the first time. Further investigations are necessary to disclose additional resistance mechanisms.
Phenotypic Insecticide Resistance in Anopheles gambiae (Diptera: Culicidae): Specific Characterization of Underlying Resistance Mechanisms Still Matters
