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Kim DY, Hii J, Chareonviriyaphap T. Air-Drying Time Affects Mortality of Pyrethroid-Susceptible Aedes aegypti Exposed to Transfluthrin-Treated Filter Papers. INSECTS 2024; 15:616. [PMID: 39194820 DOI: 10.3390/insects15080616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Revised: 08/09/2024] [Accepted: 08/13/2024] [Indexed: 08/29/2024]
Abstract
Increasing temperature can enhance the geographical spread and behavior of disease vector mosquitoes, exposing vulnerable populations to Aedes-borne viruses and infections. To address this risk, cost-effective and sustained intervention vector control tools are required, such as volatile pyrethroid spatial repellents. This study used a high-throughput screening system toxicity bioassay to determine the discriminating concentrations of transfluthrin-treated filter papers with variable air-drying times exposed to pyrethroid-susceptible Aedes aegypti mosquitoes. At the highest transfluthrin concentration (0.01706%), a significant reduction in mosquito mortality was observed in filter papers air-dried for 24 h compared to those air-dried for 1 h (odds ratio = 0.390, p < 0.001, 95% confidence interval: 0.23-0.66). Conversely, no significant difference in mortality was found between filter papers air-dried for 1 h and those air-dried for 12 h (odds ratio = 0.646, p = 0.107, 95% confidence interval: 0.38-1.10). The discriminating concentration was 2.8-fold higher for transfluthrin-treated filter papers air-dried for 24 h than it was for papers air-dried for 1 h, and it increased 5-fold from 1 h to 336 h of air-drying. These results show that the optimal air-drying period of transfluthrin-treated filter paper is critical, as higher discriminating concentration values may lead to underestimations of insecticide resistance. The instability of transfluthrin-treated papers necessitates the use of the World Health Organization (WHO) bottle bioassay, which is the preferred method for determining mosquito susceptibility to volatile insecticides.
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Affiliation(s)
- Dae-Yun Kim
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
- Research and Lifelong Learning Center for Urban and Environmental Entomology, Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand
| | - Jeffrey Hii
- College of Public Health, Medical & Veterinary Sciences, James Cook University, Brisbane, QL 4000, Australia
| | - Theeraphap Chareonviriyaphap
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
- Research and Lifelong Learning Center for Urban and Environmental Entomology, Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand
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Syahrani L, Asih PBS, Bowolaksono A, Dwiranti A, Zubaidah S, Rozi IE, Permana DH, Bøgh C, Bangs MJ, Grieco JP, Achee NL, Lobo NF, Syafruddin D. Impact of a spatial repellent intervention on Anopheles kdr insecticide resistance allele in Sumba, Indonesia. Malar J 2024; 23:31. [PMID: 38254131 PMCID: PMC10802001 DOI: 10.1186/s12936-024-04841-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
BACKGROUND The emergence of insecticide resistance and outdoor transmission in malaria-endemic areas underlines the urgent need to develop innovative tools, such as spatial repellents (SR), that may circumvent this residual transmission. With limited options for effective insecticides, regular resistance monitoring is warranted for selecting and using appropriate tools. This study evaluates the pyrethroid knockdown resistance (kdr) allele before and after implementing a transfluthrin-based spatial repellent (SR) intervention in placebo-treated clusters. METHODS This study looks at the frequency distribution of the kdr allele in Sumba Island from June 2015 to August 2018. Insecticide susceptibility tests were carried out on female Anopheles sp. aged 3-5 days against permethrin 21.5 μg/ml, deltamethrin 12.5 μg/ml, and transfluthrin 10 μg/ml using CDC bottle assay. PCR sequencing of representative samples from adult mosquito collections and insecticide tests revealed the presence of kdr mutations (L1014F and L1014S) in the VGSC gene. RESULTS A total of 12 Anopheles species, Anopheles tesselatus, Anopheles. aconitus, Anopheles barbirostris, Anopheles kochi, Anopheles annularis, Anopheles maculatus, Anopheles sundaicus, Anopheles flavirostris, Anopheles balabacensis, Anopheles indefinitus, Anopheles subpictus, and Anopheles vagus were analysed. Anopheles vagus and An. sundaicus predominated in the larval populations. Susceptibility assays for all insecticides identified fully susceptible phenotypes in all species examined. Anopheles increasing frequency of kdr mutant alleles during the 3 year SR deployment was observed in both SR-treated and placebo areas, a statistically significant increase occurred in each arm. However, it is unclear how significant SR is in causing the increase in mutant alleles. The L1014S, knockdown resistance east type (kdr-e) allele was detected for the first time among the mosquito samples in this study. The L1014F, knockdown resistance west type (kdr-w) allele and heteroduplex form (wild-type-mutant) were found in almost all Anopheles species examined, including An. vagus, An. aconitus, An. subpictus, An. tesselatus, An. annularis, An. flavirostris and An. sundaicus. CONCLUSION The presence of fully susceptible phenotypes over time, along with an increase in the frequency distribution of the L1014F/S mutations post-intervention, suggest drivers of resistance external to the study, including pyrethroid use in agriculture and long-lasting insecticidal nets (LLINs). However, this does not negate possible SR impacts that support resistance. More studies that enable the comprehension of possible SR-based drivers of resistance in mosquitoes need to be conducted.
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Affiliation(s)
- Lepa Syahrani
- Doctoral Program, Department of Biology, Faculty of Mathematics and Natural Sciences, University of Indonesia, Depok, Indonesia
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
| | - Puji B S Asih
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia.
| | - Anom Bowolaksono
- Department of Biology, Faculty of Mathematics and Natural Sciences, University of Indonesia, Depok, Indonesia
| | - Astari Dwiranti
- Department of Biology, Faculty of Mathematics and Natural Sciences, University of Indonesia, Depok, Indonesia
| | - Siti Zubaidah
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
| | - Ismail E Rozi
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
- Doctoral Program, Faculty of Medicine, University of Hasanuddin, Makassar, Indonesia
| | - Dendi H Permana
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
- Doctoral Program of Biomedical Sciences, Faculty of Medicine, University of Indonesia, Jakarta, Indonesia
| | - Claus Bøgh
- The Sumba Foundation, Public Health and Malaria Control, Sumba, Indonesia
| | - Michael J Bangs
- Public Health and Malaria Control, PT Freeport Indonesia, International SOS, Mimika, Indonesia
| | - John P Grieco
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, USA
| | - Nicole L Achee
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, USA
| | - Neil F Lobo
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, USA
| | - Din Syafruddin
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
- Department of Parasitology, Faculty of Medicine, Hasanuddin University, Makassar, Indonesia
- Hasanuddin University Medical Research Center (HUMRC), Makassar, Indonesia
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