Open Peer Review Any reports and responses or comments on the article can be found at the end of the article. RESEARCH ARTICLE Variations in household microclimate affect outdoor-biting behaviour of malaria vectors [version 1; peer review: 2 approved, 1 approved with reservations] Halfan S. Ngowo , Emmanuel Wilson Kaindoa , Jason Matthiopoulos , Heather M. Ferguson , Fredros O. Okumu 1-3 Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania School of Public Health, University of the Witwatersrand, Parktown, South Africa Abstract : Mosquito behaviours including the degree to which they bite Background inside houses or outside is a crucial determinant of human exposure to malaria. Whilst seasonality in mosquito vector abundance is well documented, much less is known about the impact of climate on mosquito behaviour. We investigated how variations in household microclimate affect outdoor-biting by malaria vectors, and Anopheles arabiensis Anopheles . funestus : Mosquitoes were sampled indoors and outdoors weekly using Methods human landing catches at eight households in four villages in south-eastern Tanzania, resulting in 616 trap-nights over 12 months. Daily temperature, relative humidity and rainfall were recorded. Generalized additive mixed models (GAMMs) were used to test associations between mosquito abundance and the microclimatic conditions. Generalized linear mixed models (GLMMs) were used to investigate the influence of microclimatic conditions on the tendency of vectors to bite outdoors (proportion of outdoor biting). : abundance peaked during high rainfall months Results An. arabiensis (February-May), whilst density remained stable into the dry An. funestus season (May-August) Across the range of observed household . temperatures, a rise of 1 C marginally increased nightly An. arabiensis abundance (~11%), but more prominently increased An. funestus abundance (~66%). The abundance of and An. arabiensis An. funestus showed strong positive associations with time-lagged rainfall (2-3 and 3-4 weeks before sampling). The degree of outdoor biting in was An. arabiensis significantly associated with the relative temperature difference between indoor and outdoor environments, with exophily increasing as temperature inside houses became relatively warmer. The exophily of did An. funestus not vary with temperature differences. : This study demonstrates that malaria vector Conclusions An. arabiensis shifts the location of its biting from indoors to outdoors in association with relative differences in microclimatic conditions. These environmental impacts could give rise to seasonal variation in mosquito biting behaviour 1,2 2,3 1 1 1-3 1 2 3 Reviewer Status Invited Reviewers version 1 24 Oct 2017 1 2 3 report report report , Barcelona Institute for Krijn Petrus Paaijmans Global Health (ISGlobal), Barcelona, Spain 1 , Kenya Medical Joseph M Mwangangi Research Institute (KEMRI), Kilifi, Kenya 2 , University of Ghana, Accra, Yaw A. Afrane Ghana 3 24 Oct 2017, :102 ( First published: 2 ) https://doi.org/10.12688/wellcomeopenres.12928.1 24 Oct 2017, :102 ( Latest published: 2 ) https://doi.org/10.12688/wellcomeopenres.12928.1 v1 º Page 1 of 18 Wellcome Open Research 2017, 2:102 Last updated: 23 APR 2020