Knockdown resistance mutations contributing to pyrethroid resistance in Aedes aegypti population, Saudi Arabia

AbstractThe malaria vector, Anopheles stephensi, which is typically restricted to South Asia and the Middle East, was recently detected in the Horn of Africa. Controlling the spread of this vector could involve integrated vector control that considers the status of insecticide resistance of multiple vector species in the region. Previous reports indicate that the knockdown resistance mutations (kdr) in the voltage-gated sodium channel (vgsc) are absent in both pyrethroid resistant and sensitive variants of An. stephensi in east Ethiopia but similar information on other vector species in the same areas is limited. In this study, kdr and the neighboring intron was analyzed in An. stephensi, An. arabiensis, and Culex pipiens s. l. collected in east Ethiopia between 2016 and 2017. Sequence analysis revealed that all of Cx. pipiens s.l. (n = 42) and 71.6% of the An. arabiensis (n=67) carried kdr L1014F known to confer target-site pyrethroid resistance. Intronic variation was only observed in An. stephensi (segregating sites = 6, haplotypes = 3) previously shown to have no kdr mutations. In addition, no evidence of non-neutral evolutionary processes was detected at the An. stephensi kdr intron which further supports target-site mechanism not being a major resistance mechanism in this An. stephensi population. Overall, these results suggest differences in evolved mechanisms of pyrethroid/DDT resistance in populations of vector species from the same region. Variation in insecticide resistance mechanisms in East Ethiopian mosquito vectors highlight possible species or population specific biological factors and distinct environmental exposures that shape their evolution.

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Analysis of the Knockdown Resistance Locus (kdr) in Anopheles stephensi, An. arabiensis, and Culex pipiens s.l. for Insight Into the Evolution of Target-site Pyrethroid Resistance in Eastern Ethiopia

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.20-1357 ◽

2022 ◽

Author(s):

Tamar E. Carter ◽

Araya Gebresilassie ◽

Shantoy Hansel ◽

Lambodhar Damodaran ◽

Callum Montgomery ◽

...

Keyword(s):

Culex Pipiens ◽

Anopheles Stephensi ◽

Pyrethroid Resistance ◽

Resistance Mechanism ◽

Target Site ◽

Knockdown Resistance ◽

Resistance Mutations ◽

Vector Species ◽

Eastern Ethiopia ◽

Integrated Vector Control

The malaria vector, Anopheles stephensi, which is typically restricted to South Asia and the Middle East, was recently detected in the Horn of Africa. Addressing the spread of this vector could involve integrated vector control that considers the status of insecticide resistance of multiple vector species in the region. Previous reports indicate that the knockdown resistance mutations (kdr) in the voltage-gated sodium channel (vgsc) are absent in both pyrethroid-resistant and pyrethroid-sensitive An. stephensi in eastern Ethiopia; however, similar information about other vector species in the same areas is limited. In this study, kdr and the neighboring intron were analyzed in An. stephensi, An. arabiensis, and Culex pipiens s.l. collected between 2016 and 2017 to determine the evolutionary history of kdr in eastern Ethiopia. A sequence analysis revealed that all of Cx. pipiens s.l. (N = 42) and 71.6% of the An. arabiensis (N = 67) carried kdr L1014F, which is known to confer target-site pyrethroid resistance. Intronic variation was only observed in An. stephensi (six segregating sites, three haplotypes), which was previously shown to have no kdr mutations. In addition, no evidence of non-neutral evolutionary processes was detected at the An. stephensi kdr intron, thereby further supporting the target-site mechanism not being a major resistance mechanism in this An. stephensi population. Overall, these results show key differences in the evolution of target-site pyrethroid/dichlorodiphenyltrichloroethane resistance mutations in populations of vector species from the same region. Variations in insecticide resistance mechanism profiles between eastern Ethiopian mosquito vectors may lead to different responses to insecticides used in integrated vector control.

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Pyrethroid-Resistance and Presence of Two Knockdown Resistance (kdr) Mutations, F1534C and a Novel Mutation T1520I, in Indian Aedes aegypti

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0003332 ◽

2015 ◽

Vol 9 (1) ◽

pp. e3332 ◽

Cited By ~ 50

Author(s):

Raja Babu S. Kushwah ◽

Cherry L. Dykes ◽

Neera Kapoor ◽

Tridibes Adak ◽

Om P. Singh

Keyword(s):

Aedes Aegypti ◽

Pyrethroid Resistance ◽

Novel Mutation ◽

Knockdown Resistance

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Fitness costs of individual and combined pyrethroid resistance mechanisms, kdr and CYP-mediated detoxification, in Aedes aegypti

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009271 ◽

2021 ◽

Vol 15 (3) ◽

pp. e0009271

Author(s):

Letícia B. Smith ◽

Juan J. Silva ◽

Connie Chen ◽

Laura C. Harrington ◽

Jeffrey G. Scott

Keyword(s):

Aedes Aegypti ◽

Pyrethroid Resistance ◽

Resistance Mechanisms ◽

Fitness Cost ◽

Adult Longevity ◽

Cost Ratio ◽

Resistance Mutations ◽

Fitness Costs ◽

Net Reproductive Rate ◽

Mating Competition

Background Aedes aegypti is an important vector of many human diseases and a serious threat to human health due to its wide geographic distribution and preference for human hosts. A. aegypti also has evolved widespread resistance to pyrethroids due to the extensive use of this insecticide class over the past decades. Mutations that cause insecticide resistance result in fitness costs in the absence of insecticides. The fitness costs of pyrethroid resistance mutations in A. aegypti are still poorly understood despite their implications for arbovirus transmission. Methodology/Principle findings We evaluated fitness based both on allele-competition and by measuring specific fitness components (i.e. life table and mating competition) to determine the costs of the different resistance mechanisms individually and in combination. We used four congenic A. aegypti strains: Rockefeller (ROCK) is susceptible to insecticides; KDR:ROCK (KR) contains only voltage-sensitive sodium channel (Vssc) mutations S989P+V1016G (kdr); CYP:ROCK (CR) contains only CYP-mediated resistance; and CYP+KDR:ROCK (CKR) contains both CYP-mediated resistance and kdr. The kdr allele frequency decreased over nine generations in the allele-competition study regardless of the presence of CYP-mediated resistance. Specific fitness costs were variable by strain and component measured. CR and CKR had a lower net reproductive rate (R0) than ROCK or KR, and KR was not different than ROCK. There was no correlation between the level of permethrin resistance conferred by the different mechanisms and their fitness cost ratio. We also found that CKR males had a reduced mating success relative to ROCK males when attempting to mate with ROCK females. Conclusions/Significance Both kdr and CYP-mediated resistance have a fitness cost affecting different physiological aspects of the mosquito. CYP-mediated resistance negatively affected adult longevity and mating competition, whereas the specific fitness costs of kdr remains elusive. Understanding fitness costs helps us determine whether and how quickly resistance will be lost after pesticide application has ceased.

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Knockdown Resistance (kdr) Mutations I1532T and F1534S Were Identified in Aedes albopictus Field Populations in Zhejiang Province, Central China

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.702081 ◽

2021 ◽

Vol 11 ◽

Author(s):

Yuyan Wu ◽

Qinmei Liu ◽

Yunpeng Qi ◽

Yinping Wu ◽

Qinxiang Ni ◽

...

Keyword(s):

Aedes Albopictus ◽

Mutant Allele ◽

Pyrethroid Resistance ◽

Southern China ◽

Zhejiang Province ◽

Central China ◽

Knockdown Resistance ◽

Resistance Mutations ◽

Deltamethrin Resistance ◽

Domain Iii

Aedes albopictus is the only vector that can transmit the dengue virus in Zhejiang Province, central China, and it can develop insecticide resistance due to long-term exposure to pyrethroids. The presence of knockdown resistance (kdr) mutations is one of the mechanisms responsible for pyrethroid resistance, and has been reported in some Ae. albopictus populations in southern China. However, little is known about the DNA diversity of the voltage-gated sodium channel (VGSC) gene in Ae. albopictus populations in central China. Four Ae. albopictus field populations were collected, in Yiwu (YW), Quzhou (QZ), Wenzhou (WZ), and Jiaxing (JX) from Zhejiang Province, central China. The susceptibility of Ae. albopictus adults to three pyrethroids (beta-cypermethrin, deltamethrin, and permethrin) was tested using the WHO tube assay, and Kdr mutations were identified via PCR and sequencing. The relationship between kdr mutations and pyrethroid phenotypes was also analyzed. Of the four populations, none was sensitive to any pyrethroid tested, and the YW population showed the strongest pyrethroid resistance. Non-synonymous kdr mutations were detected in codons 1532 and 1534, domain III. At codon 1534, one mutant allele, TCC(S), was detected in the four populations with a frequency of 42.08%, while at codon 1532, one mutant allele, ACC(T), was detected in the JX and QZ populations, with frequencies of 4.22 and 3.03%, respectively. The F1534S mutant allele was positively correlated with both beta-cypermethrin and deltamethrin resistance phenotypes (OR > 1, P < 0.05), whereas the I1532T mutant allele was possibly negatively correlated with beta-cypermethrin, deltamethrin, and permethrin resistance phenotypes (OR < 1, P > 0.05). In conclusion, resistance and resistance mutations regarding to three pyrethroids are already present in the Ae. Albopictus populations from Zhejiang, central China, which prompts the need to use non-insecticide-based methods of insect control.

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Permethrin resistance in Aedes aegypti: Genomic variants that confer knockdown resistance, recovery, and death

PLoS Genetics ◽

10.1371/journal.pgen.1009606 ◽

2021 ◽

Vol 17 (6) ◽

pp. e1009606

Author(s):

Karla Saavedra-Rodriguez ◽

Corey L. Campbell ◽

Saul Lozano ◽

Patricia Penilla-Navarro ◽

Alma Lopez-Solis ◽

...

Keyword(s):

Aedes Aegypti ◽

Pyrethroid Resistance ◽

Disease Outbreaks ◽

Resistance Mechanisms ◽

Target Site ◽

Detoxification Enzymes ◽

Nucleotide Polymorphisms ◽

Knockdown Resistance ◽

High Association ◽

Genomic Markers

Pyrethroids are one of the few classes of insecticides available to control Aedes aegypti, the major vector of dengue, chikungunya, and Zika viruses. Unfortunately, evolving mechanisms of pyrethroid resistance in mosquito populations threaten our ability to control disease outbreaks. Two common pyrethroid resistance mechanisms occur in Ae. aegypti: 1) knockdown resistance, which involves amino acid substitutions at the pyrethroid target site—the voltage-gated sodium channel (VGSC)—and 2) enhanced metabolism by detoxification enzymes. When a heterogeneous population of mosquitoes is exposed to pyrethroids, different responses occur. During exposure, a proportion of mosquitoes exhibit immediate knockdown, whereas others are not knocked-down and are designated knockdown resistant (kdr). When these individuals are removed from the source of insecticide, the knocked-down mosquitoes can either remain in this status and lead to dead or recover within a few hours. The proportion of these phenotypic responses is dependent on the pyrethroid concentration and the genetic background of the population tested. In this study, we sequenced and performed pairwise genome comparisons between kdr, recovered, and dead phenotypes in a pyrethroid-resistant colony from Tapachula, Mexico. We identified single-nucleotide polymorphisms (SNPs) associated with each phenotype and identified genes that are likely associated with the mechanisms of pyrethroid resistance, including detoxification, the cuticle, and insecticide target sites. We identified high association between kdr and mutations at VGSC and moderate association with additional insecticide target site, detoxification, and cuticle protein coding genes. Recovery was associated with cuticle proteins, the voltage-dependent calcium channel, and a different group of detoxification genes. We provide a list of detoxification genes under directional selection in this field-resistant population. Their functional roles in pyrethroid metabolism and their potential uses as genomic markers of resistance require validation.

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