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Title Insecticidal decay effects of long-lasting insecticide nets and indoor residual spraying on Anopheles gambiae and Anopheles arabiensis in Western Kenya Permalink
| Content Provider | Semantic Scholar |
|---|---|
| Author | Wanjala, Christine Ludwin Zhou, Guofa Mbugi, Jernard P. Simbauni, Jemimah A. Afrane, Yaw A. Ototo, Ednah N. Gesuge, Maxwell Atieli, Harrysone Etemesi Githeko, Andrew K. Yan, Guiyun |
| Copyright Year | 2015 |
| Abstract | Background: Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are the first-line tools for malaria prevention and control in Africa. Vector resistance to insecticides has been extensively studied, however the insecticidal effects of the nets and sprayed walls on pyrethroid resistant mosquitoes has not been studied thoroughly. We evaluated the bioefficacy of LLINs of different ages and lambda-cyhalothrin (ICON 10cs) on the sprayed mud walls for a period of time on malaria vector survivorship. Methods: WHO tube bioassay was performed using diagnostic doses of lambda-cyhalothrin (0.05 %), permethrin (0.75 %) and deltamethrin (0.05 %). Cone bioassays were conducted on netting materials from 0 to 3 years old long-lasting insecticide-impregnated nets. Wall bioassays were performed monthly on mud slabs sprayed with lambdacyhalothrin over a period of seven months. All bioassays used An. gambiae mosquitoes collected from the field and the laboratory susceptible reference Kisumu strain. Concentration of the insecticides on the netting materials was examined using the gas chromatography method. Mosquitoes were identified to species level using PCR and genotyped for the kdr gene mutation frequencies. Results: WHO bioassays results showed that populations from five sites were highly resistant to the pyrethroids (mortalities ranged from 52.5 to 75.3 %), and two sites were moderately resistant to these insecticides (80.4 – 87.2 %). Homozygote kdr mutations of L1014S ranged from 73 to 88 % in An. gambiae s.s. dominant populations whereas L1014S mutation frequencies were relatively low (7–31 %) in An. arabiensis dominant populations. There was a significant decrease (P < 0.05) in mosquito mortality with time after the spray with both lambda-cyhalothrin (75 % mortality after six months) and with the age of LLINs (60 % mortality after 24 month). Field collected mosquitoes were able to survive exposure to both IRS and LLINs even with newly sprayed walls (86.6–93.5 % mortality) and new LLINs (77.5–85.0 % mortality), Wild mosquitoes collected from the field had significantly lower mortality rates to LLINs (59.6–85.0 %) than laboratory reared susceptible strain (100 %). Insecticide concentration decreased significantly from 0.14 μg/ml in the new nets to 0.077 μg/ml in nets older than 18 months (P < 0.05). (Continued on next page) * Correspondence: guiyuny@uci.edu Program in Public Health, University of California, Irvine, CA 92697, USA Full list of author information is available at the end of the article © 2015 Wanjala et al. Open Access This 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. Wanjala et al. Parasites & Vectors (2015) 8:588 DOI 10.1186/s13071-015-1194-6 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://cloudfront.escholarship.org/dist/prd/content/qt704914zc/qt704914zc.pdf?t=om3rdr |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
