Insecticide resistance and genetic structure of Aedes aegypti populations from Rio de Janeiro State, Brazil

Vector control largely relies on neurotoxic chemicals, and insecticide resistance (IR) directly threatens their effectiveness. In some cases, specific alleles cause IR, and knowledge of the genetic diversity and gene flow among mosquito populations is crucial to track their arrival, rise, and spread. Here we evaluated Aedes aegypti populations’ susceptibility status, collected in 2016 from six different municipalities of Rio de Janeiro state (RJ), to temephos, pyriproxyfen, malathion, and deltamethrin. We collected eggs of Ae. aegypti in Campos dos Goytacazes (Cgy), Itaperuna (Ipn), Iguaba Grande (Igg), Itaboraí (Ibr), Mangaratiba (Mgr), and Vassouras (Vsr). We followed the World Health Organization (WHO) guidelines and investigated the degree of susceptibility/resistance of mosquitoes to these insecticides. We used the Rockefeller strain as a susceptible positive control. We genotyped the V1016I and F1534C knockdown resistance (kdr) alleles using qPCR TaqMan SNP genotyping assay. Besides, with the use of Ae. aegypti SNP-chip, we performed genomic population analyses by genotyping more than 15,000 biallelic SNPs in mosquitoes from each population. We added previous data from populations from other countries to evaluate the ancestry of RJ populations. All RJ Ae. aegypti populations were susceptible to pyriproxyfen and malathion and highly resistant to deltamethrin. The resistance ratios for temephos was below 3,0 in Cgy, Ibr, and Igg populations, representing the lowest rates since IR monitoring started in this Brazilian region. We found the kdr alleles in high frequencies in all populations, partially justifying the observed resistance to pyrethroid. Population genetics analysis showed that Ae. aegypti revealed potential higher migration among some RJ localities and low genetic structure for most of them. Future population genetic studies, together with IR data in Ae aegypti on a broader scale, can help us predict the gene flow within and among the Brazilian States, allowing us to track the dynamics of arrival and changes in the frequency of IR alleles, and providing critical information to improving vector control program.

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Insecticide resistance in dengue vectors from hotspots in Selangor, Malaysia

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009205 ◽

2021 ◽

Vol 15 (3) ◽

pp. e0009205

Author(s):

Rosilawati Rasli ◽

Yoon Ling Cheong ◽

M. Khairuddin Che Ibrahim ◽

Siti Futri Farahininajua Fikri ◽

Rusydi Najmuddin Norzali ◽

...

Keyword(s):

Aedes Aegypti ◽

Insecticide Resistance ◽

Vector Control ◽

Aedes Albopictus ◽

World Health ◽

Dengue Vector ◽

Organophosphate Insecticide ◽

Potential Threat ◽

Pyrethroid Insecticides ◽

Dengue Vector Control

Background In Malaysia, dengue remains a top priority disease and usage of insecticides is the main method for dengue vector control. Limited baseline insecticide resistance data in dengue hotspots has prompted us to conduct this study. The present study reports the use of a map on the insecticide susceptibility status of Aedes aegypti and Aedes albopictus to provide a quick visualization and overview of the distribution of insecticide resistance. Method and results The insecticide resistance status of Aedes populations collected from 24 dengue hotspot areas from the period of December 2018 until June 2019 was proactively monitored using the World Health Organization standard protocol for adult and larval susceptibility testing was conducted, together with elucidation of the mechanisms involved in observed resistance. For resistance monitoring, susceptibility to three adulticides (permethrin, deltamethrin, and malathion) was tested, as well as susceptibility to the larvicide, temephos. Data showed significant resistance to both deltamethrin and permethrin (pyrethroid insecticides), and to malathion (organophosphate insecticide) in all sampled Aedes aegypti populations, while variable resistance patterns were found in the sampled Aedes albopictus populations. Temephos resistance was observed when larvae were tested using the diagnostic dosage of 0.012mg/L but not at the operational dosage of 1mg/L for both species. Conclusion The present study highlights evidence of a potential threat to the effectiveness of insecticides currently used in dengue vector control, and the urgent requirement for insecticide resistance management to be integrated into the National Dengue Control Program.

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A Challenge for a Unique Dengue Vector Control Programme: Assessment of the Spatial Variation of Insecticide Resistance Status amongst Aedes aegypti and Aedes albopictus Populations in Gampaha District, Sri Lanka

BioMed Research International ◽

10.1155/2021/6619175 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Rasika Dalpadado ◽

Nayana Gunathilaka ◽

Deepika Amarasinghe ◽

Lahiru Udayanaga

Keyword(s):

Sri Lanka ◽

Aedes Aegypti ◽

Insecticide Resistance ◽

Vector Control ◽

Aedes Albopictus ◽

Rural Areas ◽

Medical Officer ◽

Public Health Problem ◽

World Health ◽

Susceptibility Status

Background. To date, dengue is considered an important public health problem in Sri Lanka. Irrational use of insecticides without evidence-based applications has primed the development of resistance in mosquito vectors. Method. The present study investigated the resistance status of Aedes aegypti and Aedes albopictus to commonly used insecticides in three selected Medical Officer of Health (MOH) areas (i.e., Attanagalla, Dompe, and Negombo) in Gampaha District, Western Province of Sri Lanka. Entomological surveys were performed using ovitraps and larval collections. Larval bioassays were carried out to determine the LC50, LC90, and LC95 and susceptibility status for organophosphate temephos, whereas adult bioassays were performed to test the 0.03% deltamethrin and 0.8% malathion susceptibility. Results. The study revealed that the temephos concentrations required to control Ae. aegypti (13.7-17.7 times) and Ae. albopictus (4.6-7.6 times) are higher than the diagnostic concentration (0.012 mg/L) proposed by the World Health Organization. The highest resistance levels were observed for both Ae. aegypti ( 14 ± 1.87 ) and Ae. albopictus ( 36 ± 1.87 ) collected from the Negombo MOH area. Therefore, the WHO recommended diagnostic concentration is no longer effective in controlling Ae. aegypti and Ae. albopictus larvae in these areas. Both the dengue vectors have evolved a high level of insecticide resistance to malathion and deltamethrin in the Gampaha District except Ae. albopictus mosquitoes in rural areas. Further, vectors in rural areas are indicated susceptible (>98%) to pyrethroids and emergence of resistance (<97%) for organophosphate insecticides. Conclusion. The results of this study warrant the vector management authorities on the proper application of insecticides and rational use in vector control. The susceptibility status of vector mosquitoes should be continuously monitored especially in dengue-endemic areas parallel to the routine surveillance programme. Further molecular studies are strongly recommended to determine the Knockdown Resistance (kdr) mutations among Aedes populations.

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The influence of roads on the fine-scale population genetic structure of the dengue vector Aedes aegypti (Linnaeus)

10.1101/2020.09.07.285528 ◽

2020 ◽

Author(s):

Maria Angenica Fulo Regilme ◽

Thaddeus Carvajal ◽

Ann –Christin Honnen ◽

Divina Amalin ◽

Kozo Watanabe

Keyword(s):

Gene Flow ◽

Genetic Structure ◽

Aedes Aegypti ◽

Spatial Scale ◽

Population Genetic Structure ◽

Population Genetic ◽

Population Control ◽

Control Program ◽

Fine Spatial Scale ◽

The Road

AbstractDengue is endemic in tropical and subtropical countries and is transmitted mainly by Aedes aegypti. Mosquito movement can be affected by human-made structures such as roads that can act as a barrier. Roads can influence the population genetic structure of Ae. aegypti. We investigated the genetic structure and gene flow of Ae. aegypti as influenced by a primary road, España Boulevard (EB) with 2000-meter-long stretch and 24-meters-wide in a very fine spatial scale. We hypothesized that Ae. aegypti populations separated by EB will be different due to the limited gene flow as caused by the barrier effect of the road. A total of 376 adults and larval Ae. aegypti were collected from June to September 2017 in 21 sites across EB. North (N1-N11) and South (S1-S10) comprised of 211 and 165 individuals, respectively. All mosquitoes were genotyped at 11 microsatellite loci. AMOVA FST indicated significant genetic differentiation across the road. The constructed UPGMA dendrogram found 4 genetic groups revealing the clear separation between North and South sites across the road. On the other hand, Bayesian cluster analysis showed four genetic clusters (K = 4) wherein each individual samples have no distinct genetic cluster thus genetic admixture. Moreover, significant positive spatial autocorrelation was observed at 100 - 200 m distance class, suggesting dispersal potential of the adult mosquitoes within a 200 m spatial scale. Our results suggest that human-made landscape features such as primary roads are potential barriers to mosquito movement thereby limiting its gene flow across the road. This information is valuable in designing an effective mosquito control program in a very fine spatial scale.Author SummaryDengue, a mosquito-borne viral infection is a serious health problem in tropical and subtropical countries such as Philippines. Most dengue prevention programs aim to eradicate its mosquito vector, Aedes aegypti. A successful population control program is reliant in understanding the mosquito behavior and ecology including how human-made structures such as roads influence its expansion and movement. Previous studies have discovered the barrier effect of roads in the movement of mosquitoes. In this study, we examined the influence of roads in the population genetic structure of Ae. aegypti in a fine spatial scale using 11 microsatellite markers. We found significant genetic differentiation of mosquito populations across the road. Our results suggest limited gene flow across the road and supports our hypothesis that roads are potential barriers to mosquito dispersal. This information can be used in designing an effective mosquito population control zones in perceived barrier to mosquito dispersal such as roads.

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Larvicidal Effectiveness of Azolla pinnata against Aedes aegypti (Diptera: Culicidae) with Its Effects on Larval Morphology and Visualization of Behavioural Response

Journal of Parasitology Research ◽

10.1155/2018/1383186 ◽

2018 ◽

Vol 2018 ◽

pp. 1-5 ◽

Cited By ~ 4

Author(s):

Nor Shaida Husna Zulkrnin ◽

Nurul Nadiah Rozhan ◽

Nur Amanina Zulkfili ◽

Nik Raihan Nik Yusoff ◽

Mohd Sukhairi Mat Rasat ◽

...

Keyword(s):

Aedes Aegypti ◽

Mosquito Control ◽

Larval Mortality ◽

Control Program ◽

Test Method ◽

World Health ◽

Azolla Pinnata ◽

Agricultural Field ◽

Aquatic Fern ◽

Significant Difference

Dengue is vector-borne diseases with 390 million infections per year extending over 120 countries of the world. Aedes aegypti (L.) (Diptera: Culicidae) is a primary vector for dengue viral infections for humans. Current focus on application of natural product against mosquito vectors has been the main priority for research due to its eco-safety. The extensive use of chemical insecticides has led to severe health problems, environmental pollution, toxic hazards to human and nontarget species, and development of insecticide resistance on mosquitoes. Azolla pinnata is an aquatic fern and predominantly used as feed in poultry industry and as fertilizer in agricultural field for enhancing the fertility of rice paddy soil. The present study was conducted to explore the larvicidal efficacy of A. pinnata using fresh and powdered form against late third-stage larvae (6 days, 5 mm in larvae body length) of Ae. aegypti (L.) (Diptera: Culicidae). The larvicidal bioassays were performed using World Health Organization standard larval susceptibility test method for different concentration for powdered and fresh A. pinnata. Powdered A. pinnata concentration used during larvicidal bioassay ranges from 500ppm to 2000ppm; meanwhile, fresh A. pinnata ranges from 500ppm to 9,000,000 ppm. The highest mortality was at 1853 ppm for powdered A. pinnata compared with fresh A. pinnata at 2,521,535 ppm, while the LC50 for both powdered and fresh A. pinnata recorded at 1262 ppm and 1853 ppm, respectively. Finally, the analysis of variance (ANOVA) showed significant difference on Ae. aegypti larval mortality (F=30.439, df=1, p≤0.001) and concentration (F=20.002, df=1, p≤0.001) compared to powdered and fresh A. pinnata at 24-hour bioassay test. In conclusion, the powdered A. pinnata serves as a good larvicidal agent against Ae. aegypti (L.) (Diptera: Culicidae) and this study provided information on the lethal concentration that may have potential for a more eco-friendly Aedes mosquito control program.

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Incidência das Formas Imaturas de Aedes albopictus (Skuse) e Aedes aegypti (Linnaeus) no Município de Miguel Pereira, RJ, Brasil

EntomoBrasilis ◽

10.12741/ebrasilis.v3i2.80 ◽

2010 ◽

Vol 3 (2) ◽

pp. 55-58 ◽

Cited By ~ 1

Author(s):

Paulo Roberto Moreira Barbosa ◽

William Costa Rodrigues ◽

Marise Maleck de Oliveira Cabral

Keyword(s):

Aedes Aegypti ◽

Aedes Albopictus ◽

Urban Areas ◽

Rio De Janeiro ◽

Average Rate ◽

Public Health Problem ◽

Waste Land ◽

Immature Form ◽

Relationship Of ◽

Janeiro State

A presença de Aedes albopictus (Skuse) em área urbana representa um risco potencial do inter-relacionamento dessa espécie de mosquito com a população. Este estudo teve como objetivo identificar as formas imaturas de Ae. albopictus encontradas nos depósitos e imóveis do município de Miguel Pereira. O estudo foi realizado no período de 12 meses, ano de 2007, em 27 locais do município de Miguel Pereira, Estado do Rio de Janeiro. As larvas encontradas foram identificadas em laboratório e a análise dos dados foi calculada pelos índices de infestação predial e índice de Breteau. Os tipos de imóveis positivos foram residências (79,44% do total); terrenos baldios (2,56%); comércios (2,56%) e outros tipos de imóveis (15,04%) para Ae. albopictus, e residências (72,72% do total); comércios (6,06%); terrenos baldios (3,03%); e outros tipos de imóveis (18,18%) para Aedes aegypti (L.). Das 3731 larvas, 3562 (95,5%) eram de Ae. albopictus e 169 (4,5%) de Ae. aegypti. O mosquito Ae. albopictus mostrou-se mais presente nos criadouros que Ae. aegypti. A média do índice de infestação predial (IFP) e índice de Breteau (IB) para Ae. albopictus foi 1,0 e 1,9 e para Ae. aegypti de 0,1 e 0,1, respectivamente. As formas imaturas mais abundantemente encontradas no Município de Miguel Pereira no ano de 2007 foram de Ae. albopictus podendo futuramente se tornar um problema de saúde pública. Incidence of Aedes albopictus (Skuse) Immature Form in Miguel Pereira, RJ, Brazil. Abstract. The presence of Aedes albopictus (Skuse) in urban areas represents a potential risk of inter-relationship of this species of mosquito with the population. This study aimed to evaluate the presence of the Ae. albopictus immature forms in deposits and building at Miguel Pereira city, Rio de Janeiro State. The study was carried in the last 12 months, 2007, in 27 locations in Miguel Pereira city. The larvae were identified in laboratory and data analysis was calculated by indicators of building infestation index and the Breteau index. The positive buildings were: residential (79.44% of total); waste land (2.56%), shopping (2.56%) and other types of buildings (15.04%) to Ae. albopictus, and homes (72.72% of total), shopping (6.06%); waste land (3.03%) and other types of buildings (18.18%) to Ae. aegypti (L.). The larvae (3731) collected, 3562 (95.5%) were Ae. albopictus and 169 (4.5%) were Ae. aegypti. The Ae. albopictus are more present in breeding that Ae. aegypti. The average rate of building infestation index (IFP) and Breteau index (IB) for Ae. albopictus was 1.0 and 1.9 and for Ae. aegypti was 0.1 and 0.1, respectively. The Ae. albopictus immature larvae forms were more abundantly found in the Miguel Pereira city in 2007; in future it may become a public health problem.

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The influence of roads on the fine-scale population genetic structure of the dengue vector Aedes aegypti (Linnaeus)

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009139 ◽

2021 ◽

Vol 15 (2) ◽

pp. e0009139

Author(s):

Maria Angenica F. Regilme ◽

Thaddeus M. Carvajal ◽

Ann–Christin Honnen ◽

Divina M. Amalin ◽

Kozo Watanabe

Keyword(s):

Gene Flow ◽

Genetic Structure ◽

Aedes Aegypti ◽

Spatial Scale ◽

Population Genetic Structure ◽

Population Genetic ◽

Mosquito Control ◽

Genetic Admixture ◽

Fine Spatial Scale ◽

The Road

Dengue is endemic in tropical and subtropical countries and is transmitted mainly by Aedes aegypti. Mosquito movement can be affected by human-made structures such as roads that can act as a barrier. Roads can influence the population genetic structure of Ae. aegypti. We investigated the genetic structure and gene flow of Ae. aegypti as influenced by a primary road, España Boulevard (EB) with 2000-meter-long stretch and 24-meters-wide in a very fine spatial scale. We hypothesized that Ae. aegypti populations separated by EB will be different due to the limited gene flow as caused by the barrier effect of the road. A total of 359 adults and 17 larvae Ae. aegypti were collected from June to September 2017 in 13 sites across EB. North (N1-N8) and South (S1-S5) comprised of 211 and 165 individuals, respectively. All mosquitoes were genotyped at 11 microsatellite loci. AMOVA FST indicated significant genetic differentiation across the road. The constructed UPGMA dendrogram found 3 genetic groups revealing the clear separation between North and South sites across the road. On the other hand, Bayesian cluster analysis showed four genetic clusters (K = 4) wherein each individual samples have no distinct genetic cluster thus genetic admixture. Our results suggest that human-made landscape features such as primary roads are potential barriers to mosquito movement thereby limiting its gene flow across the road. This information is valuable in designing an effective mosquito control program in a very fine spatial scale.

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A differential expression of pyrethroid resistance genes in the malaria vector Anopheles funestus across Uganda is associated with patterns of gene flow

PLoS ONE ◽

10.1371/journal.pone.0240743 ◽

2020 ◽

Vol 15 (11) ◽

pp. e0240743

Author(s):

Maurice Marcel Sandeu ◽

Charles Mulamba ◽

Gareth D. Weedall ◽

Charles S. Wondji

Keyword(s):

Population Structure ◽

Gene Flow ◽

Genetic Structure ◽

Genetic Differentiation ◽

Insecticide Resistance ◽

Pyrethroid Resistance ◽

Anopheles Funestus ◽

Metabolic Resistance ◽

Transcription Analysis ◽

Genome Wide

Background Insecticide resistance is challenging the effectiveness of insecticide-based control interventions to reduce malaria burden in Africa. Understanding the molecular basis of insecticides resistance and patterns of gene flow in major malaria vectors such as Anopheles funestus are important steps for designing effective resistance management strategies. Here, we investigated the association between patterns of genetic structure and expression profiles of genes involved in the pyrethroid resistance in An. funestus across Uganda and neighboring Kenya. Methods Blood-fed mosquitoes An. funestus were collected across the four localities in Uganda and neighboring Kenya. A Microarray-based genome-wide transcription analysis was performed to identify the set of genes associated with permethrin resistance. 17 microsatellites markers were genotyped and used to establish patterns of genetic differentiation. Results Microarray-based genome-wide transcription profiling of pyrethroid resistance in four locations across Uganda (Arua, Bulambuli, Lira, and Tororo) and Kenya (Kisumu) revealed that resistance was mainly driven by metabolic resistance. The most commonly up-regulated genes in pyrethroid resistance mosquitoes include cytochrome P450s (CYP9K1, CYP6M7, CYP4H18, CYP4H17, CYP4C36). However, expression levels of key genes vary geographically such as the P450 CYP6M7 [Fold-change (FC) = 115.8 (Arua) vs 24.05 (Tororo) and 16.9 (Kisumu)]. In addition, several genes from other families were also over-expressed including Glutathione S-transferases (GSTs), carboxylesterases, trypsin, glycogenin, and nucleotide binding protein which probably contribute to insecticide resistance across Uganda and Kenya. Genotyping of 17 microsatellite loci in the five locations provided evidence that a geographical shift in the resistance mechanisms could be associated with patterns of population structure throughout East Africa. Genetic and population structure analyses indicated significant genetic differentiation between Arua and other localities (FST>0.03) and revealed a barrier to gene flow between Arua and other areas, possibly associated with Rift Valley. Conclusion The correlation between patterns of genetic structure and variation in gene expression could be used to inform future interventions especially as new insecticides are gradually introduced.

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Co-occurrence of kdr Mutations V1016I and F1534C and Its Association With Phenotypic Resistance to Pyrethroids in Aedes aegypti (Diptera: Culicidae) Populations From Costa Rica

Journal of Medical Entomology ◽

10.1093/jme/tjz241 ◽

2019 ◽

Vol 57 (3) ◽

pp. 830-836

Author(s):

Aryana Zardkoohi ◽

David Castañeda ◽

Juan C Lol ◽

Carmen Castillo ◽

Francisco Lopez ◽

...

Keyword(s):

Costa Rica ◽

Aedes Aegypti ◽

Insecticide Resistance ◽

Vector Control ◽

Strong Association ◽

Resistance Management ◽

Management Plan ◽

Costa Rican ◽

Mosquito Vector ◽

Phenotypic Resistance

Abstract Aedes aegypti (Linnaeus, 1762) is considered the most important mosquito vector species for several arboviruses (e.g., dengue, chikungunya, Zika) in Costa Rica. The primary strategy for the control and prevention of Aedes-borne diseases relies on insecticide-based vector control. However, the emergence of insecticide resistance in the mosquito populations presents a significant threat to these prevention actions. The characterization of the mechanisms driving the insecticide resistance in Ae. aegypti is vital for decision making in vector control programs. Therefore, we analyzed the voltage-gated sodium channel (VGSC) gene for the presence of the V1016I and F1534C kdr mutations in Ae. aegypti populations from Puntarenas and Limon provinces, Costa Rica. The CDC bottle bioassays showed that both Costa Rican Ae. aegypti populations were resistant to permethrin and deltamethrin. In the case of kdr genotyping, results revealed the co-occurrence of V1016I and F1534C mutations in permethrin and deltamethrin-resistant populations, as well as the fixation of the 1534C allele. A strong association between these mutations and permethrin and deltamethrin resistance was found in Puntarenas. Limon did not show this association; however, our results indicate that the Limon population analyzed is not under the same selective pressure as Puntarenas for the VGSC gene. Therefore, our findings make an urgent call to expand the knowledge about the insecticide resistance status and mechanisms in the Costa Rican populations of Ae. aegypti, which must be a priority to develop an effective resistance management plan.

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