PMID- 32287300 OWN - NLM STAT- MEDLINE DCOM- 20200720 LR - 20240425 IS - 1932-6203 (Electronic) IS - 1932-6203 (Linking) VI - 15 IP - 4 DP - 2020 TI - Longevity of the insecticidal effect of three pyrethroid formulations applied to outdoor vegetation on a laboratory-adapted colony of the Southeast Asian malaria vector Anopheles dirus. PG - e0231251 LID - 10.1371/journal.pone.0231251 [doi] LID - e0231251 AB - Outdoor residual spraying is proposed for the control of exophilic mosquitoes. However, the residual effect of insecticide mists applied to outdoor resting habitats of mosquitoes is not well characterized. The objective of this study was to assess the longevity of the residual insecticidal effect of three pyrethroid formulations applied to outdoor vegetation against the Southeast Asian malaria vector Anopheles dirus. Lambda-cyhalothrin capsule suspension, deltamethrin emulsifiable concentrate and bifenthrin wettable powder were sprayed on dense bamboo bushes on the Thailand-Myanmar border during the dry season 2018. The duration and magnitude of the residual insecticidal effect were assessed weekly with a standard cone assay, using freshly collected insecticide-treated bamboo leaves and a laboratory-adapted colony of Anopheles dirus sensu stricto susceptible to pyrethroids. The experiment was repeated during the rainy season to assess the persistence of the lambda-cyhalothrin formulation after natural rains and artificial washings. During the dry season (cumulative rainfall = 28 mm in 111 days), mortality and knockdown (KD) rates were >80% for 60 days with bifenthrin and 90 days with lambda-cyhalothrin and deltamethrin. The 50% knockdown time (TKD50) was <15 min with lambda-cyhalothrin and deltamethrin, and <30 min with bifenthrin. During the rainy season (cumulative rainfall = 465 mm in 51 days), mortality and KD rates were >80% for 42 days and TKD50 was <15 min with lambda-cyhalothrin. Additional artificial washing of the testing material with 10L of tap water before performing the cone tests had no significant effect on the residual insecticidal effect of this formulation. Long-lasting residual insecticidal effect can be obtained when spraying pyrethroid insecticides on the outdoor resting habitats of malaria vectors. FAU - Chaumeau, Victor AU - Chaumeau V AUID- ORCID: 0000-0003-0171-2176 AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. AD - Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, United Kingdom. FAU - Wisisakun, Praphan AU - Wisisakun P AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. FAU - Sawasdichai, Sunisa AU - Sawasdichai S AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. FAU - Kankew, Prasan AU - Kankew P AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. FAU - Htoo, Gay Nay AU - Htoo GN AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. FAU - Saithanmettajit, Somsak AU - Saithanmettajit S AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. FAU - Aryalamloed, Sarang AU - Aryalamloed S AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. FAU - Lee, Naw Yu AU - Lee NY AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. FAU - Delmas, Gilles AU - Delmas G AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. AD - Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, United Kingdom. FAU - Nosten, Francois AU - Nosten F AUID- ORCID: 0000-0002-7951-0745 AD - Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. AD - Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, United Kingdom. LA - eng GR - WT_/Wellcome Trust/United Kingdom GR - 101148/WT_/Wellcome Trust/United Kingdom PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20200414 PL - United States TA - PLoS One JT - PloS one JID - 101285081 RN - 0 (Insecticides) RN - 0 (Nitriles) RN - 0 (Pyrethrins) RN - 2JTS8R821G (decamethrin) RN - 6B66JED0KN (bifenthrin) RN - V0V73PEB8M (cyhalothrin) SB - IM MH - Animals MH - Anopheles/*drug effects/growth & development MH - Insect Vectors/*drug effects/growth & development MH - *Insecticide Resistance MH - Insecticides/chemistry/*pharmacology MH - Mosquito Control/*methods MH - Myanmar MH - Nitriles/chemistry/*pharmacology MH - Pyrethrins/chemistry/*pharmacology MH - Thailand PMC - PMC7156039 COIS- The authors have declared that no competing interests exist. EDAT- 2020/04/15 06:00 MHDA- 2020/07/21 06:00 PMCR- 2020/04/14 CRDT- 2020/04/15 06:00 PHST- 2019/08/08 00:00 [received] PHST- 2020/03/19 00:00 [accepted] PHST- 2020/04/15 06:00 [entrez] PHST- 2020/04/15 06:00 [pubmed] PHST- 2020/07/21 06:00 [medline] PHST- 2020/04/14 00:00 [pmc-release] AID - PONE-D-19-22372 [pii] AID - 10.1371/journal.pone.0231251 [doi] PST - epublish SO - PLoS One. 2020 Apr 14;15(4):e0231251. doi: 10.1371/journal.pone.0231251. eCollection 2020.