scholarly journals 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

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.

scholarly journals Insecticide resistance in dengue vectors from hotspots in Selangor, Malaysia

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.

scholarly journals Insecticide Susceptibility Status of Aedes albopictus in Dengue Hotspot Areas in Malaysia

2021 ◽  
Vol 14 ◽  
pp. 1-8
Author(s):  
WAN FATMA ZUHARAH ◽  
WAN FATMA ZUHARAH ◽  
Ahmad Mohiddin ◽  
Asmalia Md Lasim ◽  
Zairi Jaal ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
Continuous Monitoring ◽  
Reference Strain ◽  
Control Program ◽  
Aedes Mosquitoes ◽  
Northern District ◽  
Vector Control Program ◽  
Susceptibility Status

The vector control program has become challenging due to the resistance problem occurs in Aedes mosquitoes. Aedes albopictus (Skuse, 1894) is the most dominant species contributing as a vector of dengue, Chikungunya and Zika viruses in Malaysia. Knowledge of the current insecticide resistance of Ae. albopictus is essential for the success of vector control program. Here, we reported the susceptibility status of Ae. albopictus collected from the dengue hotspot areas in the Northern District of Penang Island, Malaysia on three common use insecticides in vector control program. Aedes albopictus was sampled from three localities at Flat Hamna, Kampung Sungai Gelugor and Kampung Tanjung Tokong in the Northern District of Penang Island, Malaysia. The adult bioassay results suggested the Flat Hamna strain (FH) was found to develop incipient resistance after 24h exposure towards all three insecticides tested; permethrin, deltamethrin and malathion (mortality 97-87%). With 1.93 fold of Resistance Ratio 50 (RR50) values, FH strains have the highest chances to develop resistance towards permethrin. Among all insecticides tested, malathion was contributed to significantly higher KdT50 in all Ae. albopictus strains as compared to VCRU reference strain (p<0.001). Thus suggesting malathion insecticide is the least effective insecticide in our vector control program. Our finding can be used as a baseline for insecticide resistance of Ae. albopictus to improve vector control across Malaysia. Permethrin and deltamethrin are still reliable to be used in the control program, nonetheless require continuous monitoring on their susceptibility towards Ae. albopictus.

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

2021 ◽  
Vol 15 (2) ◽  
pp. e0008492 ◽  
Author(s):  
Rafi Ur Rahman ◽  
Luciano Veiga Cosme ◽  
Monique Melo Costa ◽  
Luana Carrara ◽  
José Bento Pereira Lima ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Rio De Janeiro ◽  
Control Program ◽  
Positive Control ◽  
World Health ◽  
Janeiro State

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.

scholarly journals Use of Novaluron-Based Autocidal Gravid Ovitraps to Control Aedes Dengue Vector Mosquitoes in the District of Gampaha, Sri Lanka

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Gayan P. Withanage ◽  
Sameera D. Viswakula ◽  
Yasanthi Silva Gunawardene ◽  
Menaka D. Hapugoda
Keyword(s):  
Sri Lanka ◽  
Vector Control ◽  
Repeated Measures ◽  
Field Experiments ◽  
Medical Officer ◽  
Residual Effect ◽  
World Health ◽  
Local Health ◽  
Dengue Vector ◽  
Indoor And Outdoor

Dengue is the most important mosquito-borne viral infection in Sri Lanka causing an enormous social and economic burden in the country. In the absence of therapeutic drugs and the developed vaccines are under investigation, vector control is the best strategy to reduce the disease transmission. Therefore, the development of novel tools to control dengue vector mosquitoes has become the need of the hour. Novaluron is a recently developed Insect Growth Regulator (IGR) which inhibits chitin synthesis in immature stages of insects. The aim of the study was to identify the efficacy of a simple and cost-effective Autocidal Gravid Ovitrap (AGO) developed using Novaluron to control dengue outbreaks in the District of Gampaha, Sri Lanka. Laboratory and semifield experiments were performed to identify the activity range, optimum field dosage, and residual effects of Novaluron following the World Health Organization guidelines, and field experiments were performed in the Ragama Medical Officer of Health (MOH) area. Two study areas 800 m apart were selected and assigned as treated and control areas randomly. In each study area, 30 households were selected randomly. Each household was given two ovitraps, one placed indoors and the other placed outdoors. Mortality and survival counts were recorded separately for one-year time period and data were analyzed using a two-way repeated measures analysis of variance model. During the laboratory experiments, the adult emerging inhibition was 100% in all tested concentrations. The optimum field dosage was 2 ppm and the residual effect was 28 days. In the field experiments, significantly higher mortality counts were recorded in treated areas both indoor- and outdoor-placed AGOs. Two-factor repeated measures ANOVA followed by Tukey’s test confirmed that the mean mortality count is high for the developed AGOs both indoor and outdoor settings. The developed AGO can be deployed to control both indoor and outdoor dengue vector mosquito populations, and in dengue-risk areas, the ovitrap will be supportive to local health authorities to enhance the efficiency of future vector control programs.

A Simple PCR Assay for Discrimination of Dengue Vectors from Nsukka LGA, Nigeria

2020 ◽  
Vol 10 (1) ◽  
pp. 67-77
Author(s):  
Amos Watentena ◽  
Ikem Chris Okoye ◽  
Ikechukwu Eugene Onah ◽  
Onwude Cosmas Ogbonnaya ◽  
Emmanuel Ogudu
Keyword(s):  
Aedes Aegypti ◽  
Aedes Albopictus ◽  
Mosquito Species ◽  
Public Health Problem ◽  
Major Public Health Problem ◽  
Mosquito Vector ◽  
Aedes Mosquitoes ◽  
Allele Specific ◽  
Arboviral Diseases ◽  
Dengue Vectors

Mosquitoes of Aedes species are vectors of several arboviral diseases which continue to be a major public health problem in Nigeria. This study among other things, morphologically identified Aedes mosquitoes collected from Nsukka LGA and used an allele specific PCR amplification for discrimination of dengue vectors. Larval sampling, BG-sentinel traps and modified human landing catches were used for mosquito sampling in two selected autonomous communities of Nsukka LGA (Nsukka and Obimo). A total of 124 Aedes mosquitoes consisting of five (5) different species were collected from April to June, 2019 in a cross-sectional study that covered 126 households, under 76 distinct geographical coordinates. Larvae was mainly collected from plastic containers 73% (n=224), metallic containers 14% (n=43), earthen pots 9% (n=29) and used car tyres 3% (n=9), reared to adult stage 69.35% (n=86), and all mosquitoes were identified using standard morphological keys. Five (5) Aedes mosquito species were captured; Aedes aegypti 83(66.94%), Aedes albopictus 33(26.61%), Aedes simpsoni (4.48%), Aedes luteocephalus (≤1%) and Aedes vittatus (≤1%). Nsukka autonomous community had higher species diversity than Obimo. Allele specific amplification confirmed dengue vectors, Aedes aegypti and Aedes albopictus species on a 2% agarose gel. Since the most recent re-emergence of arboviral diseases is closely associated with Aedes species, findings of this study, therefore, give further evidence about the presence of potential arboviral vectors in Nigeria and describe the role of a simple PCR in discriminating some. Further entomological studies should integrate PCR assays in mosquito vector surveillance.

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

2010 ◽  
Vol 3 (2) ◽  
pp. 55-58 ◽  
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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