Semi-field studies to better understand the impact of eave tubes on mosquito mortality and behaviour
Antoine M G Barreaux, N'Guessan Brou, Alphonsine A Koffi, Raphaël N'Guessan, Welbeck A Oumbouke, Innocent Z Tia, Matthew B Thomas, Antoine M G Barreaux, N'Guessan Brou, Alphonsine A Koffi, Raphaël N'Guessan, Welbeck A Oumbouke, Innocent Z Tia, Matthew B Thomas
Abstract
Background: Eave tubes are a type of housing modification that provide a novel way of delivering insecticides to mosquitoes as they attempt to enter the house. The current study reports on a series of semi-field studies aimed at improving the understanding of how eave tubes might impact mosquito mortality and behaviour.
Methods: Experiments were conducted using West African style experimental huts at a field site in M'be, Côte d'Ivoire. Huts were modified in various ways to determine: (i) whether mosquitoes in this field setting naturally recruit to eave tubes; (ii) whether eave tubes can reduce house entry even in the absence of screening; (iii) whether mosquitoes suffer mortality if they attempt to exit a house via treated eave tubes; and, (iv) whether screening and eave tubes might deflect mosquitoes into neighbouring houses without the intervention.
Results: Ninety percent more mosquitoes (Anopheles gambiae sensu lato, and other species) entered huts through open eaves tubes compared to window slits. The addition of insecticide-treated eave tubes reduced mosquito entry by 60%, even when windows remained open. Those mosquitoes that managed to enter the huts exhibited a 64% reduction in blood feeding and a tendency for increased mortality, suggesting contact with insecticide-treated inserts prior to hut entry. When An. gambiae mosquitoes were deliberately introduced into huts with treated eave tubes, there was evidence of six times increase in overnight mortality, suggesting mosquitoes can contact treated eave tube inserts when trying to exit the hut. There was no evidence for deflection of mosquitoes from huts with screening, or screening plus eave tubes, to adjacent unmodified huts.
Conclusions: Eave tubes are a potentially effective way to target Anopheles mosquitoes with insecticides. That treated eave tubes can reduce mosquito entry even when windows are open is a potentially important result as it suggests that eave tubes might not need to be combined with household screening to have an impact on malaria transmission. The absence of deflection is also a potentially important result as coverage of eave tubes and/or screening is unlikely to be 100% and it is important that households that do not have the technology are not disadvantaged by those that do.
Keywords: Anopheles gambiae; Blood-feeding inhibition; Deflection; Housing improvement; Malaria; Mosquito entry; Vector control.
Figures
References
- World Health Organization . Global technical strategy for malaria 2016-2030. Geneva: World Health Organization; 2015.
- Barreaux P, Barreaux AMG, Sternberg ED, Suh E, Waite JL, Whitehead SA, et al. Priorities for broadening the malaria vector control tool kit. Trends Parasitol. 2017;33:763–774. doi: 10.1016/j.pt.2017.06.003.
- Killeen GF, Tatarsky A, Diabate A, Chaccour CJ, Marshall JM, Okumu FO, et al. Developing an expanded vector control toolbox for malaria elimination. BMJ Glob Health. 2017;2:e000211. doi: 10.1136/bmjgh-2016-000211.
- Knols BGJ, Farenhorst M, Andriessen R, Snetselaar J, Suer RA, Osinga AJ, et al. Eave tubes for malaria control in Africa: an introduction. Malar J. 2016;15:404. doi: 10.1186/s12936-016-1452-x.
- Snetselaar J, Njiru BN, Gachie B, Owigo P, Andriessen R, Glunt K, et al. Eave tubes for malaria control in Africa: prototyping and evaluation against Anopheles gambiae s.s. and Anopheles arabiensis under semi-field conditions in western Kenya. Malar J. 2017;16:276. doi: 10.1186/s12936-017-1926-5.
- Sternberg ED, Ng’habi KR KR, Lyimo IN, Kessy ST, Farenhorst M, Thomas MB, et al. Eave tubes for malaria control in Africa: initial development and semi-field evaluations in Tanzania. Malar J. 2016;15:447. doi: 10.1186/s12936-016-1499-8.
- Waite JL, Lynch PA, Thomas MB, Ferguson H, Dornhaus A, Beeche A, et al. Eave tubes for malaria control in Africa: a modelling assessment of potential impact on transmission. Malar J. 2016;15:449. doi: 10.1186/s12936-016-1505-1.
- Sternberg E, Cook J, Ahoua Alou LP, Aoura C, Assi SB, Koffi AA, et al. Evaluating the impact of screening plus eave tubes on malaria transmission compared to current best practice in central Côte d’Ivoire: a two armed cluster randomized controlled trial. BMC Public Health. 2018. In Press.
- Darriet F, N’Guessan R, Hougard JM, Traoré-Lamizana M, Carnevale P. An experimental tool essential for the evaluation of insecticides: the testing huts (in French) Bull Soc Pathol Exot. 2002;95:299–303.
- Koffi AA, Ahoua Alou LP, Djenontin A, Kabran J-PK, Dosso Y, Kone A, et al. Efficacy of Olyset® Duo, a permethrin and pyriproxyfen mixture net against wild pyrethroid-resistant Anopheles gambiae s.s. from Côte d’Ivoire: an experimental hut trial. Parasite. 2015;22:28. doi: 10.1051/parasite/2015028.
- Koffi AA, Ahoua Alou LP, Adja MA, Chandre F, Pennetier C. Insecticide resistance status of Anopheles gambiae s.s population from M’Bé: a WHOPES-labelled experimental hut station, 10 years after the political crisis in Côte d’Ivoire. Malar J. 2013;12:151. doi: 10.1186/1475-2875-12-151.
- Zoh DD, Ahoua Alou LP, Toure M, Pennetier C, Camara S, Traore DF, et al. The current insecticide resistance status of Anopheles gambiae (s.l.) (Culicidae) in rural and urban areas of Bouaké, Côte d’Ivoire. Parasit Vectors. 2018;11:118. doi: 10.1186/s13071-018-2702-2.
- Glunt KD, Coetzee M, Huijben S, Koffi AA, Lynch PA, N’Guessan R, et al. Empirical and theoretical investigation into the potential impacts of insecticide resistance on the effectiveness of insecticide-treated bed nets. Evol Appl. 2018;11:431–441. doi: 10.1111/eva.12574.
- Djènontin A, Chabi J, Baldet T, Irish S, Pennetier C, Hougard J-M, et al. Managing insecticide resistance in malaria vectors by combining carbamate-treated plastic wall sheeting and pyrethroid-treated bed nets. Malar J. 2009;8:233. doi: 10.1186/1475-2875-8-233.
- Oumbouke WA, Fongnikin A, Soukou KB, Moore SJ, N’Guessan R. Relative performance of indoor vector control interventions in the Ifakara and the West African experimental huts. Parasit Vectors. 2017;10:432. doi: 10.1186/s13071-017-2365-4.
- or . Accessed 29 May 2018.
- Barr DJ, Levy R, Scheepers C, Tily HJ. Random effects structure for confirmatory hypothesis testing: keep it maximal. J Mem Lang. 2013;68:255–278. doi: 10.1016/j.jml.2012.11.001.
- Matuschek H, Kliegl R, Vasishth S, Baayen H, Bates D. Balancing type I error and power in linear mixed models. J Mem Lang. 2017;94:305–315. doi: 10.1016/j.jml.2017.01.001.
- Bolker BM, Brooks ME, Clark CJ, Geange SW, Poulsen JR, Stevens MHH, et al. Generalized linear mixed models: a practical guide for ecology and evolution. Trends Ecol Evol. 2009;24:127–135. doi: 10.1016/j.tree.2008.10.008.
- Luke SG. Evaluating significance in linear mixed-effects models in R. Behav Res Methods. 2017;49:1494–1502. doi: 10.3758/s13428-016-0809-y.
- Kuznetsova A, Christensen RHB, Bavay C, Brockhoff PB. Automated mixed ANOVA modeling of sensory and consumer data. Food Qual Prefer. 2015;40:31–38. doi: 10.1016/j.foodqual.2014.08.004.
- Kuznetsova A, Brockhoff PB, Christensen RHB. lmerTest package: tests in linear mixed effects models. J Stat Softw. 2017;82:1–26. doi: 10.18637/jss.v082.i13.
- Lindsay SW, Adiamah JH, Armstrong JRM. The effect of permethrin-impregnated bednets on house entry by mosquitoes (Diptera: Culicidae) in The Gambia. Bull Entomol Res. 1992;82:49. doi: 10.1017/S0007485300051488.
- Maia MF, Onyango SP, Thele M, Simfukwe ET, Turner EL, Moore SJ. Do topical repellents divert mosquitoes within a community? Health equity implications of topical repellents as a mosquito bite prevention tool. PLoS One. 2013;8:e84875. doi: 10.1371/journal.pone.0084875.
- Cator L. Malaria altering host attractiveness and mosquito feeding. Trends Parasitol. 2017;33(5):338–339. doi: 10.1016/j.pt.2017.03.003.
- Vantaux A, Yao F, Hien DF, Guissou E, Yameogo BK, Gouagna L-C, et al. Field evidence for manipulation of mosquito host selection by the human malaria parasite, Plasmodium falciparum. bioRxiv. 2018;207183.
- WHO | Global plan for insecticide resistance management in malaria vectors. WHO. World Health Organization; 2018.
- Sternberg ED, Thomas MB. Insights from agriculture for the management of insecticide resistance in disease vectors. Evol Appl. 2018;11:404–414. doi: 10.1111/eva.12501.
Source: PubMed