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Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania
BACKGROUND: Culex mosquitoes cause considerable biting nuisance and sporadic transmission of arboviral and filarial diseases. METHODS: Using standard World Health Organization procedures, insecticide resistance profiles and underlying mechanisms were investigated during dry and wet seasons of 2015 a...
Autores principales: | , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6708135/ https://www.ncbi.nlm.nih.gov/pubmed/31443737 http://dx.doi.org/10.1186/s13071-019-3676-4 |
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author | Matowo, Nancy S. Abbasi, Said Munhenga, Givemore Tanner, Marcel Mapua, Salum A. Oullo, David Koekemoer, Lizette L. Kaindoa, Emanuel Ngowo, Halfan S. Coetzee, Maureen Utzinger, Jürg Okumu, Fredros O. |
author_facet | Matowo, Nancy S. Abbasi, Said Munhenga, Givemore Tanner, Marcel Mapua, Salum A. Oullo, David Koekemoer, Lizette L. Kaindoa, Emanuel Ngowo, Halfan S. Coetzee, Maureen Utzinger, Jürg Okumu, Fredros O. |
author_sort | Matowo, Nancy S. |
collection | PubMed |
description | BACKGROUND: Culex mosquitoes cause considerable biting nuisance and sporadic transmission of arboviral and filarial diseases. METHODS: Using standard World Health Organization procedures, insecticide resistance profiles and underlying mechanisms were investigated during dry and wet seasons of 2015 and 2016 in Culex pipiens complex from three neighbouring administrative wards in Ulanga District, Tanzania. Synergist tests with piperonyl butoxide, diethyl maleate, and triphenyl phosphate, were employed to investigate mechanisms of the observed resistance phenotypes. Proportional biting densities of Culex species, relative to other taxa, were determined from indoor surveillance data collected in 2012, 2013, and 2015. RESULTS: Insecticide resistance varied significantly between wards and seasons. For example, female mosquitoes in one ward were susceptible to bendiocarb and fenitrothion in the wet season, but resistant during the dry season, while in neighbouring ward, the mosquitoes were fully susceptible to these pesticides in both seasons. Similar variations occurred against bendiocarb, DDT, deltamethrin, and lambda-cyhalothrin. Surprisingly, with the exception of one ward in the wet season, the Culex populations were susceptible to permethrin, commonly used on bednets in the area. No insecticide resistance was observed against the organophosphates, pirimiphos-methyl and malathion, except for one incident of reduced susceptibility in the dry season. Synergist assays revealed possible involvement of monooxygenases, esterases, and glutathione S-transferase in pyrethroid and DDT resistance. Morphology-based identification and molecular assays of adult Culex revealed that 94% were Cx. pipiens complex, of which 81% were Cx. quinquefasciatus, 2% Cx. pipiens, and 3% hybrids. About 14% of the specimens were non-amplified during molecular identifications. Female adults collected indoors were 100% Cx. pipiens complex, and constituted 79% of the overall biting risk. CONCLUSIONS: The Cx. pipiens complex constituted the greatest biting nuisance inside people’s houses, and showed resistance to most public health insecticides possible. Resistance varied at a fine geographical scale, between adjacent wards, and seasons, which warrants some modifications to current insecticide resistance monitoring strategies. Resistance phenotypes are partly mediated by metabolic mechanisms, but require further evaluation through biochemical and molecular techniques. The high densities and resistance in Culex could negatively influence the acceptability of other interventions such as those used against malaria mosquitoes. |
format | Online Article Text |
id | pubmed-6708135 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-67081352019-08-28 Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania Matowo, Nancy S. Abbasi, Said Munhenga, Givemore Tanner, Marcel Mapua, Salum A. Oullo, David Koekemoer, Lizette L. Kaindoa, Emanuel Ngowo, Halfan S. Coetzee, Maureen Utzinger, Jürg Okumu, Fredros O. Parasit Vectors Research BACKGROUND: Culex mosquitoes cause considerable biting nuisance and sporadic transmission of arboviral and filarial diseases. METHODS: Using standard World Health Organization procedures, insecticide resistance profiles and underlying mechanisms were investigated during dry and wet seasons of 2015 and 2016 in Culex pipiens complex from three neighbouring administrative wards in Ulanga District, Tanzania. Synergist tests with piperonyl butoxide, diethyl maleate, and triphenyl phosphate, were employed to investigate mechanisms of the observed resistance phenotypes. Proportional biting densities of Culex species, relative to other taxa, were determined from indoor surveillance data collected in 2012, 2013, and 2015. RESULTS: Insecticide resistance varied significantly between wards and seasons. For example, female mosquitoes in one ward were susceptible to bendiocarb and fenitrothion in the wet season, but resistant during the dry season, while in neighbouring ward, the mosquitoes were fully susceptible to these pesticides in both seasons. Similar variations occurred against bendiocarb, DDT, deltamethrin, and lambda-cyhalothrin. Surprisingly, with the exception of one ward in the wet season, the Culex populations were susceptible to permethrin, commonly used on bednets in the area. No insecticide resistance was observed against the organophosphates, pirimiphos-methyl and malathion, except for one incident of reduced susceptibility in the dry season. Synergist assays revealed possible involvement of monooxygenases, esterases, and glutathione S-transferase in pyrethroid and DDT resistance. Morphology-based identification and molecular assays of adult Culex revealed that 94% were Cx. pipiens complex, of which 81% were Cx. quinquefasciatus, 2% Cx. pipiens, and 3% hybrids. About 14% of the specimens were non-amplified during molecular identifications. Female adults collected indoors were 100% Cx. pipiens complex, and constituted 79% of the overall biting risk. CONCLUSIONS: The Cx. pipiens complex constituted the greatest biting nuisance inside people’s houses, and showed resistance to most public health insecticides possible. Resistance varied at a fine geographical scale, between adjacent wards, and seasons, which warrants some modifications to current insecticide resistance monitoring strategies. Resistance phenotypes are partly mediated by metabolic mechanisms, but require further evaluation through biochemical and molecular techniques. The high densities and resistance in Culex could negatively influence the acceptability of other interventions such as those used against malaria mosquitoes. BioMed Central 2019-08-23 /pmc/articles/PMC6708135/ /pubmed/31443737 http://dx.doi.org/10.1186/s13071-019-3676-4 Text en © The Author(s) 2019 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Matowo, Nancy S. Abbasi, Said Munhenga, Givemore Tanner, Marcel Mapua, Salum A. Oullo, David Koekemoer, Lizette L. Kaindoa, Emanuel Ngowo, Halfan S. Coetzee, Maureen Utzinger, Jürg Okumu, Fredros O. Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania |
title | Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania |
title_full | Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania |
title_fullStr | Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania |
title_full_unstemmed | Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania |
title_short | Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania |
title_sort | fine-scale spatial and temporal variations in insecticide resistance in culex pipiens complex mosquitoes in rural south-eastern tanzania |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6708135/ https://www.ncbi.nlm.nih.gov/pubmed/31443737 http://dx.doi.org/10.1186/s13071-019-3676-4 |
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