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Fillinger U, Denz A, Njoroge MM, Tambwe MM, Takken W, van Loon JJA, Moore SJ, Saddler A, Chitnis N, Hiscox A. A randomized, double-blind placebo-control study assessing the protective efficacy of an odour-based 'push-pull' malaria vector control strategy in reducing human-vector contact. Sci Rep 2023; 13:11197. [PMID: 37433881 DOI: 10.1038/s41598-023-38463-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 07/08/2023] [Indexed: 07/13/2023] Open
Abstract
Novel malaria vector control strategies targeting the odour-orientation of mosquitoes during host-seeking, such as 'attract-and-kill' or 'push-and-pull', have been suggested as complementary tools to indoor residual spraying and long-lasting insecticidal nets. These would be particularly beneficial if they can target vectors in the peri-domestic space where people are unprotected by traditional interventions. A randomized double-blind placebo-control study was implemented in western Kenya to evaluate: a 'push' intervention (spatial repellent) using transfluthrin-treated fabric strips positioned at open eave gaps of houses; a 'pull' intervention placing an odour-baited mosquito trap at a 5 m distance from a house; the combined 'push-pull' package; and the control where houses contained all elements but without active ingredients. Treatments were rotated through 12 houses in a randomized-block design. Outdoor biting was estimated using human landing catches, and indoor mosquito densities using light-traps. None of the interventions provided any protection from outdoor biting malaria vectors. The 'push' reduced indoor vector densities dominated by Anopheles funestus by around two thirds. The 'pull' device did not add any benefit. In the light of the high Anopheles arabiensis biting densities outdoors in the study location, the search for efficient outdoor protection and effective pull components needs to continue.
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Affiliation(s)
- Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (Icipe), Human Health Theme, Nairobi, 00100, Kenya.
| | - Adrian Denz
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
| | - Margaret M Njoroge
- International Centre of Insect Physiology and Ecology (Icipe), Human Health Theme, Nairobi, 00100, Kenya
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Mohamed M Tambwe
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU), Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Joop J A van Loon
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Sarah J Moore
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU), Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), Tengeru, P.O. Box 447, Arusha, Tanzania
| | - Adam Saddler
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Vector Control Product Testing Unit (VCPTU), Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Telethon Kids Institute, Perth, Australia
| | - Nakul Chitnis
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University & Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- Arctech Innovation Ltd., The Cube, Londoneast-Uk Business and Technical Park, Yew Tree Avenue, Dagenham, RM10 7FN, UK
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Roth MA, Lahondère C, Gross AD. Discovering Aethina tumida responses to attractant and repellent molecules: A potential basis for future management strategies. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 192:105386. [PMID: 37105615 DOI: 10.1016/j.pestbp.2023.105386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/21/2023] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
Small hive beetle (Aethina tumida) management has been highly dependent upon chemical and mechanical control over the past two decades; however, many of these methods have not been consistently effective or safe for European honey bee (Apis mellifera) colonies. Here we explore the behavioral and physiological effects of the attractants isopentyl acetate and pollen patty upon A. tumida adults, and also investigate the mixture of attractants with repellent compounds, which were previously untested against A. tumida. Electroantennograms established sensitivity of A. tumida antennae to both attractants and all repellents with the exception of DEET, with antennae displaying greatest sensitivity to the repellent pyrrolidine. A walking-response olfactometer, designed specifically for A. tumida, was used for all behavioral experiments. It was found that both pollen patty and isopentyl acetate were attractive to A. tumida adults; conversely, mixes of attractants and repellent volatiles led to less attraction or avoidance of what was previously a significantly attractive source. Of all repellents tested, pyrrolidine was found to be the most repelling molecule, with significant avoidance of the attractive source at a 10 mg treatment of pyrrolidine. The results of this study indicate that, at the behavioral level, the repellent compounds pyrrolidine and 1,4-dimethylpiperazine resulted in a negative preference index indicating a repellent behavioral response. By strategically implementing a repellent source in an apiary environment, A. tumida adults could be deterred from entering and invading hives.
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Affiliation(s)
- Morgan A Roth
- Molecular Physiology and Toxicology Laboratory, Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States of America
| | - Chloé Lahondère
- Department of Biochemistry, Virginia Polytechnic and State University, Blacksburg, VA 24061, United States of America
| | - Aaron D Gross
- Molecular Physiology and Toxicology Laboratory, Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States of America.
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Owino EA. Human and plant volatiles; lures for mosquito, vectors of dengue virus and malaria. J Vector Borne Dis 2021; 58:1-11. [PMID: 34818857 DOI: 10.4103/0972-9062.318313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Increased outbreaks of mosquito borne diseases like the deadly parasitic disease, malaria and arboviruses like Zika, yellow fever and dengue viruses around the world have led to increased interest in traps that could effectively be used against mosquitoes. For example, a Google search at the time of this writing, asking, 'which is the best way of trapping mosquitoes?' produced 35.5 million search results. Regardless of the interest in the subject, scientists have yet to find a definitive answer to these questions. One area that has been exploited as a potential source of efficient traps for mosquitoes is host odour baits. Since mosquitoes are attracted to their hosts through odours produced by the hosts, it's highly likely that synthetic chemical blends based on host odours could provide a solution. Most mosquito species have 2 hosts: vertebrate animals and vascular plants. Amongst the vertebrates, most diseases spread by mosquitoes are to humans. Considerable research has therefore been conducted on human odours that elicit attraction in mosquitoes, with emphasis on compounds from sweat and skin. Interest on plant volatiles is currently gathering pace because unlike human odours that only attract host seeking female mosquitoes, plant odours can attract both male and female mosquitoes of all gonotrophic stages. This review article concentrates on some of the chemical compounds in human and plant host odours that have shown a potential as attractants to mosquitoes especially Aedes aegypti and Anopheles gambiae s.l.
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Buxton M, Buxton MP, Machekano H, Nyamukondiwa C, Wasserman RJ. A Survey of Potentially Pathogenic-Incriminated Arthropod Vectors of Health Concern in Botswana. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:10556. [PMID: 34639855 PMCID: PMC8508065 DOI: 10.3390/ijerph181910556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/20/2021] [Accepted: 09/27/2021] [Indexed: 11/17/2022]
Abstract
Arthropod vectors play a crucial role in the transmission of many debilitating infections, causing significant morbidity and mortality globally. Despite the economic significance of arthropods to public health, public knowledge on vector biology, ecology and taxonomic status remains anecdotal and largely unexplored. The present study surveyed knowledge gaps regarding the biology and ecology of arthropod vectors in communities of Botswana, across all districts. Results showed that communities are largely aware of individual arthropod vectors; however, their 'potential contribution' in disease transmission in humans, livestock and wildlife could not be fully attested. As such, their knowledge was largely limited with regards to some aspects of vector biology, ecology and control. Communities were strongly concerned about the burden of mosquitoes, cockroaches, flies and ticks, with the least concerns about fleas, bedbugs and lice, although the same communities did not know of specific diseases potentially vectored by these arthropods. Knowledge on arthropod vector control was mainly limited to synthetic chemical pesticides for most respondents, regardless of their location. The limited knowledge on potentially pathogen-incriminated arthropod vectors reported here has large implications for bridging knowledge gaps on the bio-ecology of these vectors countrywide. This is potentially useful in reducing the local burden of associated diseases and preventing the risk of emerging and re-emerging infectious diseases under global change.
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Affiliation(s)
- Mmabaledi Buxton
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P/Bag 016, Palapye 10071, Botswana; (H.M.); (C.N.); (R.J.W.)
| | - Malebogo Portia Buxton
- Department of Sociology, University of Botswana, P/Bag UB 0022, Gaborone 00704, Botswana;
| | - Honest Machekano
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P/Bag 016, Palapye 10071, Botswana; (H.M.); (C.N.); (R.J.W.)
| | - Casper Nyamukondiwa
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P/Bag 016, Palapye 10071, Botswana; (H.M.); (C.N.); (R.J.W.)
| | - Ryan John Wasserman
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P/Bag 016, Palapye 10071, Botswana; (H.M.); (C.N.); (R.J.W.)
- Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa
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Dormont L, Mulatier M, Carrasco D, Cohuet A. Mosquito Attractants. J Chem Ecol 2021; 47:351-393. [PMID: 33725235 DOI: 10.1007/s10886-021-01261-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/18/2021] [Accepted: 03/02/2021] [Indexed: 01/01/2023]
Abstract
Vector control and personal protection against anthropophilic mosquitoes mainly rely on the use of insecticides and repellents. The search for mosquito-attractive semiochemicals has been the subject of intense studies for decades, and new compounds or odor blends are regularly proposed as lures for odor-baited traps. We present a comprehensive and up-to-date review of all the studies that have evaluated the attractiveness of volatiles to mosquitoes, including individual chemical compounds, synthetic blends of compounds, or natural host or plant odors. A total of 388 studies were analysed, and our survey highlights the existence of 105 attractants (77 volatile compounds, 17 organism odors, and 11 synthetic blends) that have been proved effective in attracting one or several mosquito species. The exhaustive list of these attractants is presented in various tables, while the most common mosquito attractants - for which effective attractiveness has been demonstrated in numerous studies - are discussed throughout the text. The increasing knowledge on compounds attractive to mosquitoes may now serve as the basis for complementary vector control strategies, such as those involving lure-and-kill traps, or the development of mass trapping. This review also points out the necessity of further improving the search for new volatile attractants, such as new compound blends in specific ratios, considering that mosquito attraction to odors may vary over the life of the mosquito or among species. Finally, the use of mosquito attractants will undoubtedly have an increasingly important role to play in future integrated vector management programs.
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Affiliation(s)
- Laurent Dormont
- CEFE, Univ Paul Valéry Montpellier 3, CNRS, Univ Montpellier, EPHE, IRD, Montpellier, France.
| | - Margaux Mulatier
- Institut Pasteur de Guadeloupe, Laboratoire d'étude sur le contrôle des vecteurs (LeCOV), Lieu-Dit Morne Jolivièrex, 97139, Les Abymes, Guadeloupe, France
| | - David Carrasco
- MIVEGEC, Univ. Montpellier, IRD, CNRS, Montpellier, France
| | - Anna Cohuet
- MIVEGEC, Univ. Montpellier, IRD, CNRS, Montpellier, France
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Hellewell J, Sherrard-Smith E, Ogoma S, Churcher TS. Assessing the impact of low-technology emanators alongside long-lasting insecticidal nets to control malaria. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190817. [PMID: 33357051 PMCID: PMC7776935 DOI: 10.1098/rstb.2019.0817] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2020] [Indexed: 01/19/2023] Open
Abstract
Malaria control in sub-Saharan Africa relies on the widespread use of long-lasting insecticidal nets (LLINs) or the indoor residual spraying of insecticide. Disease transmission may be maintained even when these indoor interventions are universally used as some mosquitoes will bite in the early morning and evening when people are outside. As countries seek to eliminate malaria, they can target outdoor biting using new vector control tools such as spatial repellent emanators, which emit airborne insecticide to form a protective area around the user. Field data are used to incorporate a low-technology emanator into a mathematical model of malaria transmission to predict its public health impact across a range of scenarios. Targeting outdoor biting by repeatedly distributing emanators alongside LLINs increases the chance of elimination, but the additional benefit depends on the level of anthropophagy in the local mosquito population, emanator effectiveness and the pre-intervention proportion of mosquitoes biting outdoors. High proportions of pyrethroid-resistant mosquitoes diminish LLIN impact because of reduced mosquito mortality. When mosquitoes are highly anthropophagic, this reduced mortality leads to more outdoor biting and a reduced additional benefit of emanators, even if emanators are assumed to retain their effectiveness in the presence of pyrethroid resistance. Different target product profiles are examined, which show the extra epidemiological benefits of spatial repellents that induce mosquito mortality. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Joel Hellewell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London W2 1PG, UK
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London W2 1PG, UK
| | - Sheila Ogoma
- Ifakara Health Institute, Biomedical and Environmental Thematic Group, PO Box 53, Ifakara, Morogoro, United Republic of Tanzania
| | - Thomas S. Churcher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London W2 1PG, UK
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Denz A, Njoroge MM, Tambwe MM, Champagne C, Okumu F, van Loon JJA, Hiscox A, Saddler A, Fillinger U, Moore SJ, Chitnis N. Predicting the impact of outdoor vector control interventions on malaria transmission intensity from semi-field studies. Parasit Vectors 2021; 14:64. [PMID: 33472661 PMCID: PMC7819244 DOI: 10.1186/s13071-020-04560-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 12/21/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Semi-field experiments with human landing catch (HLC) measure as the outcome are an important step in the development of novel vector control interventions against outdoor transmission of malaria since they provide good estimates of personal protection. However, it is often infeasible to determine whether the reduction in HLC counts is due to mosquito mortality or repellency, especially considering that spatial repellents based on volatile pyrethroids might induce both. Due to the vastly different impact of repellency and mortality on transmission, the community-level impact of spatial repellents can not be estimated from such semi-field experiments. METHODS We present a new stochastic model that is able to estimate for any product inhibiting outdoor biting, its repelling effect versus its killing and disarming (preventing host-seeking until the next night) effects, based only on time-stratified HLC data from controlled semi-field experiments. For parameter inference, a Bayesian hierarchical model is used to account for nightly variation of semi-field experimental conditions. We estimate the impact of the products on the vectorial capacity of the given Anopheles species using an existing mathematical model. With this methodology, we analysed data from recent semi-field studies in Kenya and Tanzania on the impact of transfluthrin-treated eave ribbons, the odour-baited Suna trap and their combination (push-pull system) on HLC of Anopheles arabiensis in the peridomestic area. RESULTS Complementing previous analyses of personal protection, we found that the transfluthrin-treated eave ribbons act mainly by killing or disarming mosquitoes. Depending on the actual ratio of disarming versus killing, the vectorial capacity of An. arabiensis is reduced by 41 to 96% at 70% coverage with the transfluthrin-treated eave ribbons and by 38 to 82% at the same coverage with the push-pull system, under the assumption of a similar impact on biting indoors compared to outdoors. CONCLUSIONS The results of this analysis of semi-field data suggest that transfluthrin-treated eave ribbons are a promising tool against malaria transmission by An. arabiensis in the peridomestic area, since they provide both personal and community protection. Our modelling framework can estimate the community-level impact of any tool intervening during the mosquito host-seeking state using data from only semi-field experiments with time-stratified HLC.
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Affiliation(s)
- Adrian Denz
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland.
- University of Basel, Petersplatz 1, Basel, Switzerland.
| | - Margaret M Njoroge
- Human Health Theme, International Centre of Insect Physiology and Ecology (icipe), 00100, Nairobi, Kenya
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Mgeni M Tambwe
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Clara Champagne
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
| | - Fredros Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Public Health, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa
- School of Life Science and Biotechnology, Nelson Mandela African Institution of Science and Technology, P.O. Box 447, Arusha, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Joop J A van Loon
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- ARCTEC, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK
| | - Adam Saddler
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Ulrike Fillinger
- Human Health Theme, International Centre of Insect Physiology and Ecology (icipe), 00100, Nairobi, Kenya
| | - Sarah J Moore
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Nakul Chitnis
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland
- University of Basel, Petersplatz 1, Basel, Switzerland
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Njoroge MM, Fillinger U, Saddler A, Moore S, Takken W, van Loon JJA, Hiscox A. Evaluating putative repellent 'push' and attractive 'pull' components for manipulating the odour orientation of host-seeking malaria vectors in the peri-domestic space. Parasit Vectors 2021; 14:42. [PMID: 33430963 PMCID: PMC7802213 DOI: 10.1186/s13071-020-04556-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/16/2020] [Indexed: 12/17/2022] Open
Abstract
Background Novel malaria vector control approaches aim to combine tools for maximum protection. This study aimed to evaluate novel and re-evaluate existing putative repellent ‘push’ and attractive ‘pull’ components for manipulating the odour orientation of malaria vectors in the peri-domestic space. Methods Anopheles arabiensis outdoor human landing catches and trap comparisons were implemented in large semi-field systems to (i) test the efficacy of Citriodiol® or transfluthrin-treated fabric strips positioned in house eave gaps as push components for preventing bites; (ii) understand the efficacy of MB5-baited Suna-traps in attracting vectors in the presence of a human being; (iii) assess 2-butanone as a CO2 replacement for trapping; (iv) determine the protection provided by a full push-pull set up. The air concentrations of the chemical constituents of the push–pull set-up were quantified. Results Microencapsulated Citriodiol® eave strips did not provide outdoor protection against host-seeking An. arabiensis. Transfluthrin-treated strips reduced the odds of a mosquito landing on the human volunteer (OR 0.17; 95% CI 0.12–0.23). This impact was lower (OR 0.59; 95% CI 0.52–0.66) during the push-pull experiment, which was associated with low nighttime temperatures likely affecting the transfluthrin vaporisation. The MB5-baited Suna trap supplemented with CO2 attracted only a third of the released mosquitoes in the absence of a human being; however, with a human volunteer in the same system, the trap caught < 1% of all released mosquitoes. The volunteer consistently attracted over two-thirds of all mosquitoes released. This was the case in the absence (‘pull’ only) and in the presence of a spatial repellent (‘push-pull’), indicating that in its current configuration the tested ‘pull’ does not provide a valuable addition to a spatial repellent. The chemical 2-butanone was ineffective in replacing CO2. Transfluthrin was detectable in the air space but with a strong linear reduction in concentrations over 5 m from release. The MB5 constituent chemicals were only irregularly detected, potentially suggesting insufficient release and concentration in the air for attraction. Conclusion This step-by-step evaluation of the selected ‘push’ and ‘pull’ components led to a better understanding of their ability to affect host-seeking behaviours of the malaria vector An. arabiensis in the peri-domestic space and helps to gauge the impact such tools would have when used in the field for monitoring or control.![]()
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Affiliation(s)
- Margaret Mendi Njoroge
- International Centre of Insect Physiology and Ecology (icipe), Human Health Theme, Nairobi, 00100, Kenya.,Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (icipe), Human Health Theme, Nairobi, 00100, Kenya.
| | - Adam Saddler
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 833, Basel, Switzerland.,University of Basel, Petersplatz 1, Basel, Switzerland.,Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Sarah Moore
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 833, Basel, Switzerland.,University of Basel, Petersplatz 1, Basel, Switzerland.,Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Joop J A van Loon
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Alexandra Hiscox
- International Centre of Insect Physiology and Ecology (icipe), Human Health Theme, Nairobi, 00100, Kenya.,Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands.,London School of Hygiene and Tropical Medicine, ARCTEC, Keppel Street, London, WC1E 7HT, UK
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Taking the 'I' out of LLINs: using insecticides in vector control tools other than long-lasting nets to fight malaria. Malar J 2020; 19:73. [PMID: 32059675 PMCID: PMC7023706 DOI: 10.1186/s12936-020-3151-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/05/2020] [Indexed: 11/23/2022] Open
Abstract
Long-lasting insecticidal nets, or LLINs, have significantly reduced malaria morbidity and mortality over the past two decades. The net provides a physical barrier that decreases human-mosquito contact and the impregnated insecticide kills susceptible mosquito vectors upon contact and may repel them. However, the future of LLINs is threatened as resistance to pyrethroids is now widespread, the chemical arsenal for LLINs is very limited, time from discovery of next-generation insecticides to market is long, and persistent transmission is frequently caused by vector populations avoiding contact with LLINs. Here we ask the question whether, given these challenges, insecticides should be incorporated in nets at all. We argue that developing long-lasting nets without insecticide(s) can still reduce vector populations and provide both personal and community protection, if combined with other approaches or technologies. Taking the insecticide out of the equation (i) allows for a faster response to the current pyrethroid resistance crisis, (ii) avoids an LLIN-treadmill aimed at replacing failing bed nets due to insecticide resistance, and (iii) permits the utilization of our current and future insecticidal arsenal for other vector control tools to target persistent malaria transmission.
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Mwanga EP, Mmbando AS, Mrosso PC, Stica C, Mapua SA, Finda MF, Kifungo K, Kafwenji A, Monroe AC, Ogoma SB, Ngowo HS, Okumu FO. Eave ribbons treated with transfluthrin can protect both users and non-users against malaria vectors. Malar J 2019; 18:314. [PMID: 31533739 PMCID: PMC6751741 DOI: 10.1186/s12936-019-2958-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 09/11/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Eave ribbons treated with spatial repellents effectively prevent human exposure to outdoor-biting and indoor-biting malaria mosquitoes, and could constitute a scalable and low-cost supplement to current interventions, such as insecticide-treated nets (ITNs). This study measured protection afforded by transfluthrin-treated eave ribbons to users (personal and communal protection) and non-users (only communal protection), and whether introducing mosquito traps as additional intervention influenced these benefits. METHODS Five experimental huts were constructed inside a 110 m long, screened tunnel, in which 1000 Anopheles arabiensis were released nightly. Eave ribbons treated with 0.25 g/m2 transfluthrin were fitted to 0, 1, 2, 3, 4 or 5 huts, achieving 0, 20, 40, 60, 80 and 100% coverage, respectively. Volunteers sat near each hut and collected mosquitoes attempting to bite them from 6 to 10 p.m. (outdoor-biting), then went indoors to sleep under untreated bed nets, beside which CDC-light traps collected mosquitoes from 10 p.m. to 6 a.m. (indoor-biting). Caged mosquitoes kept inside the huts were monitored for 24 h-mortality. Separately, eave ribbons, UV-LED mosquito traps (Mosclean) or both the ribbons and traps were fitted, each time leaving the central hut unfitted to represent non-user households and assess communal protection. Biting risk was measured concurrently in all huts, before and after introducing interventions. RESULTS Transfluthrin-treated eave ribbons provided 83% and 62% protection indoors and outdoors respectively to users, plus 57% and 48% protection indoors and outdoors to the non-user. Protection for users remained constant, but protection for non-users increased with eave ribbons coverage, peaking once 80% of huts were fitted. Mortality of mosquitoes caged inside huts with eave ribbons was 100%. The UV-LED traps increased indoor exposure to users and non-users, but marginally reduced outdoor-biting. Combining the traps and eave ribbons did not improve user protection relative to eave ribbons alone. CONCLUSION Transfluthrin-treated eave ribbons protect both users and non-users against malaria mosquitoes indoors and outdoors. The mosquito-killing property of transfluthrin can magnify the communal benefits by limiting unwanted diversion to non-users, but should be validated in field trials against pyrethroid-resistant vectors. Benefits of the UV-LED traps as an intervention alone or alongside eave ribbons were however undetectable in this study. These findings extend the evidence that transfluthrin-treated eave ribbons could complement ITNs.
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Affiliation(s)
- Emmanuel P Mwanga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania.
| | - Arnold S Mmbando
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Paul C Mrosso
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Caleb Stica
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Salum A Mapua
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Marceline F Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Khamis Kifungo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Andrew Kafwenji
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - April C Monroe
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
- University of Basel, Basel, Switzerland
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland
| | - Sheila B Ogoma
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- School of Public Health, University of Witwatersrand, Johannesburg, South Africa
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11
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Evaluating synthetic odours and trap designs for monitoring Anopheles farauti in Queensland, Australia. Malar J 2019; 18:299. [PMID: 31477123 PMCID: PMC6721334 DOI: 10.1186/s12936-019-2923-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/17/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Monitoring of malaria vectors is important for designing and maintaining effective control interventions as changes in vector-feeding habits can threaten the efficacy of interventions. At present, human landing catches remain the most common method for monitoring malaria vectors of the Anopheles punctulatus complex, including the Anopheles farauti group. The aims of this study were to evaluate the efficacy of different lures and fan-powered traps, including an odour blend that has been demonstrated to be attractive to African anophelines, in Queensland, Australia. METHODS To evaluate the performance of different lures in trapping An. farauti in the field, four Suna traps were baited with either: CO2-alone, a synthetic lure (MB5 or BG-Lure) plus CO2, or a human odour plus CO2 and set in the field in Cairns, eastern Australia. A second study evaluated the performance of four traps: a Passive Box trap, BG-Suna trap, BG-Sentinel 2 trap, and BG-Bowl trap, for their ability to trap An. farauti using the best lure from the first experiment. In both experiments, treatments were rotated according to a Latin square design over 16 nights. Trapped mosquitoes were identified on the basis of their morphological features. RESULTS BG-Suna traps baited with CO2 alone, a BG-Lure plus CO2 or a natural human odour plus CO2 captured comparable numbers of An. farauti. However, the number of An. farauti sensu lato captured when the MB5 lure was used with CO2 was three times lower than when the other odour lures were used. The BG-Sentinel 2 trap, BG-Suna trap and BG-Bowl trap all captured high numbers of An. farauti, when baited with CO2 and a BG-Lure. The morphological condition of captured mosquitoes was affected by mechanical damage caused by all fan-powered traps but it was still possible to identify the specimens. CONCLUSIONS The BG-Sentinel 2 trap, BG-Suna trap and the BG-Bowl trap captured high numbers of An. farauti in the field, when equipped with CO2 and an odour lure (either the BG-Lure or a natural odour). The most important attractant was CO2. This study shows that fan-powered traps, baited with CO2 plus an appropriate odour lure, can be a promising addition to current vector monitoring methods in the Southwest Pacific.
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12
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Biting patterns of malaria vectors of the lower Shire valley, southern Malawi. Acta Trop 2019; 197:105059. [PMID: 31194960 DOI: 10.1016/j.actatropica.2019.105059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 12/13/2022]
Abstract
Assessing the biting behaviour of malaria vectors plays an integral role in understanding the dynamics of malaria transmission in a region. Biting times and preference for biting indoors or outdoors varies among mosquito species and across regions. These behaviours may also change over time in response to vector control measures such as long-lasting insecticidal nets (LLINs). Data on these parameters can provide the sites and times at which different interventions would be effective for vector control. This study assessed the biting patterns of malaria vectors in Chikwawa district, southern Malawi. The study was conducted during the dry and wet seasons in 2016 and 2017, respectively. In each season, mosquitoes were collected indoors and outdoors for 24 nights in six houses per night using the human landing catch. Volunteers were organized into six teams of two individuals, whereby three teams collected mosquitoes indoors and the other three collected mosquitoes outdoors each night, and the teams were rotated among twelve houses. All data were analyzed using Poisson log-linear models. The most abundant species were Anopheles gambiae sensu lato (primarily An. arabiensis) and An. funestus s.l. (exclusively An. funestus s.s.). During the dry season, the biting activity of An. gambiaes.l. was constant outdoors across the categorized hours (18:00 h to 08:45 h), but highest in the late evening hours (21:00 h to 23:45 h) during the wet season. The biting activity of An. funestus s.l. was highest in the late evening hours (21:00 h to 23:45 h) during the dry season and in the late night hours (03:00 h to 05:45 h) during the wet season. Whereas the number of An. funestuss.l. biting was constant (P = 0.662) in both seasons, that of An. gambiaes.l. was higher during the wet season than in the dry season (P = 0.001). Anopheles gambiae s.l. was more likely to bite outdoors than indoors in both seasons. During the wet season, An. funestus s.l. was more likely to bite indoors than outdoors but during the dry season, the bites were similar both indoors and outdoors. The biting activity that occurred in the early and late evening hours, both indoors and outdoors coincides with the times at which individuals may still be awake and physically active, and therefore unprotected by LLINs. Additionally, a substantial number of anopheline bites occurred outdoors. These findings imply that LLINs would only provide partial protection from malaria vectors, which would affect malaria transmission in this area. Therefore, protection against bites by malaria mosquitoes in the early and late evening hours is essential and can be achieved by designing interventions that reduce vector-host contacts during this period.
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Ciera L, Beladjal L, Van Landuyt L, Menger D, Holdinga M, Mertens J, Van Langenhove L, De Clerk K, Gheysens T. Electrospinning repellents in polyvinyl alcohol-nanofibres for obtaining mosquito-repelling fabrics. ROYAL SOCIETY OPEN SCIENCE 2019; 6:182139. [PMID: 31598223 PMCID: PMC6731725 DOI: 10.1098/rsos.182139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 07/24/2019] [Indexed: 06/10/2023]
Abstract
Recently, the use of repellents for preventing the transmission of mosquito-borne diseases is getting increasingly more attention. However, most of the current repellents are volatile in nature and must be frequently re-applied as their efficacy is only limited to a short period of time. Therefore, a slow release and abrasion-resistant mechanism is needed for prolonging the protection time of the repellents. The focus of this study is on the direct micro-encapsulation of repellents from an emulsion and integration of already encapsulated repellents into nanofibres via electrospinning. Different repellents were electrospun in polyvinyl alcohol (PVA) nanofibrous structures, namely p-menthane-3,8-diol micro-capsules, permethrin, chilli and catnip oil. The repellents were successfully incorporated in the nanofibres and the tensile properties of the resulting samples did not have a significant change. This means that the newly created textiles were identical to current PVA nanofibrous textiles with the added benefit of being mosquito repellent. Principally, all incorporated repellents in the nanofibrous structures showed a significantly reduced number of mosquito landings compared to the control. Consequently, the currently described method resulted in a new and very effective repelling textile material that can be used in the prevention against mosquito-associated diseases.
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Affiliation(s)
- Lucy Ciera
- The Technical University of Kenya, Nairobi, Kenya
| | - Lynda Beladjal
- Biology Department, Ghent University, Terrestrial Ecology Unit, Gent, Belgium
| | - Lieve Van Landuyt
- Textile Department, Ghent University, Technologiepark, Zwijnaarde, Belgium
| | - David Menger
- Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
| | - Maarten Holdinga
- Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
| | - Johan Mertens
- Biology Department, Ghent University, Terrestrial Ecology Unit, Gent, Belgium
| | | | - Karen De Clerk
- Textile Department, Ghent University, Technologiepark, Zwijnaarde, Belgium
| | - Tom Gheysens
- Textile Department, Ghent University, Technologiepark, Zwijnaarde, Belgium
- Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium
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14
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Abstract
For the control and elimination of malaria, information on the local vector dynamics is essential. This information provides guidance on appropriate and timely deployment of vector control tools and their subsequent success. The data on the dynamics of local mosquito populations can be collected using many different Anopheles sampling methods. Dependent on the objectives, resources, time, and local environment, different traps and methods can be chosen. This chapter describes the sampling of adult populations, focusing on the important preparatory stages and some of the widely used sampling methods. The trapping methods discussed in this chapter are the human landing catch, human-baited net trap, animal landing catch, animal-baited net trap, CDC miniature light trap, Biogents Suna trap, peripheral net collection, pyrethrum collection, exit/entry trap, and resting shelter. For optimal deployment in the field, a step-by-step description of the sampling methods is given.
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15
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Gonzalez PV, Alvarez Costa A, Harburguer LV, Masuh HM. Quantitative Evaluation of the Behavioral Response to Attractant and Repellent Compounds in Anopheles pseudopunctipennis and Aedes aegypti (Diptera: Culicidae) Larvae. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:1388-1395. [PMID: 30753516 DOI: 10.1093/jee/toz004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Indexed: 06/09/2023]
Abstract
The mosquito Anopheles pseudopunctipennis (Theobald) is the principal vector for malaria in Latin-America. Aedes aegypti (L.) (Diptera: Culicidae) is the key vector of four important arboviral diseases: dengue, yellow fever, Zika, and chikungunya. Controlling larval stages to reduce the production of new adult mosquitoes is part of the integrated vector management strategies. However, there are few studies about the olfactory behavior on immature stages of mosquitoes, especially in An. pseudopunctipennis. In this work, we have evaluated the behavior of An. pseudopunctipennis and Ae. aegypti larvae in response to attractant or repellent stimuli through a video-tracking analysis. We used the software EthoVision to obtain behavioral variables related to the swimming activity, such as distance, speed, and mobility status. The response to the repellents stimulus results in an increase of the swimming activity and the absolute angular velocity in both species. Otherwise, the responses to the possible attractants stimulus results in a decrease of the activity of the larvae only for Ae. aegypti. The effects of these compounds were weaker in Anopheles; probably as a consequence of their adaptations to different aquatic ecosystems. The study of the larval olfactory response could contribute to the development of new control tools based on 'push-pull' strategies by 'pushing' mosquitoes away from certain places using repellents, and 'pulling' them towards other places like traps baited with attractive cues.
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Affiliation(s)
- P V Gonzalez
- Centro de Investigaciones de Plagas e Insecticidas (CONICET- CITEDEF), Juan Bautista de La Salle, Villa Martelli, Buenos Aires, Argentina
| | - A Alvarez Costa
- Centro de Investigaciones de Plagas e Insecticidas (CONICET- CITEDEF), Juan Bautista de La Salle, Villa Martelli, Buenos Aires, Argentina
| | - L V Harburguer
- Centro de Investigaciones de Plagas e Insecticidas (CONICET- CITEDEF), Juan Bautista de La Salle, Villa Martelli, Buenos Aires, Argentina
| | - H M Masuh
- Centro de Investigaciones de Plagas e Insecticidas (CONICET- CITEDEF), Juan Bautista de La Salle, Villa Martelli, Buenos Aires, Argentina
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16
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Mmbando AS, Batista EPA, Kilalangongono M, Finda MF, Mwanga EP, Kaindoa EW, Kifungo K, Njalambaha RM, Ngowo HS, Eiras AE, Okumu FO. Evaluation of a push-pull system consisting of transfluthrin-treated eave ribbons and odour-baited traps for control of indoor- and outdoor-biting malaria vectors. Malar J 2019; 18:87. [PMID: 30894185 PMCID: PMC6427877 DOI: 10.1186/s12936-019-2714-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/08/2019] [Indexed: 12/21/2022] Open
Abstract
Background Push–pull strategies have been proposed as options to complement primary malaria prevention tools, indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLINs), by targeting particularly early-night biting and outdoor-biting mosquitoes. This study evaluated different configurations of a push–pull system consisting of spatial repellents [transfluthrin-treated eave ribbons (0.25 g/m2 ai)] and odour-baited traps (CO2-baited BG-Malaria traps), against indoor-biting and outdoor-biting malaria vectors inside large semi-field systems. Methods Two experimental huts were used to evaluate protective efficacy of the spatial repellents (push-only), traps (pull-only) or their combinations (push–pull), relative to controls. Adult volunteers sat outdoors (1830 h–2200 h) catching mosquitoes attempting to bite them (outdoor-biting risk), and then went indoors (2200 h–0630 h) to sleep under bed nets beside which CDC-light traps caught host-seeking mosquitoes (indoor-biting risk). Number of traps and their distance from huts were varied to optimize protection, and 500 laboratory-reared Anopheles arabiensis released nightly inside the semi-field chambers over 122 experimentation nights. Results Push-pull offered higher protection than traps alone against indoor-biting (83.4% vs. 35.0%) and outdoor-biting (79% vs. 31%), but its advantage over repellents alone was non-existent against indoor-biting (83.4% vs. 81%) and modest for outdoor-biting (79% vs. 63%). Using two traps (1 per hut) offered higher protection than either one trap (0.5 per hut) or four traps (2 per hut). Compared to original distance (5 m from huts), efficacy of push–pull against indoor-biting peaked when traps were 15 m away, while efficacy against outdoor-biting peaked when traps were 30 m away. Conclusion The best configuration of push–pull comprised transfluthrin-treated eave ribbons plus two traps, each at least 15 m from huts. Efficacy of push–pull was mainly due to the spatial repellent component. Adding odour-baited traps slightly improved personal protection indoors, but excessive trap densities increased exposure near users outdoors. Given the marginal efficacy gains over spatial repellents alone and complexity of push–pull, it may be prudent to promote just spatial repellents alongside existing interventions, e.g. LLINs or non-pyrethroid IRS. However, since both transfluthrin and traps also kill mosquitoes, and because transfluthrin can inhibit blood-feeding, field studies should be done to assess potential community-level benefits that push–pull or its components may offer to users and non-users.
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Affiliation(s)
- Arnold S Mmbando
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.
| | - Elis P A Batista
- Laboratory of Technological Innovation of Vector Control, Department of Parasitology, Biological Science Institue, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Masoud Kilalangongono
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Marceline F Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa
| | - Emmanuel P Mwanga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa
| | - Khamis Kifungo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Rukiyah M Njalambaha
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Alvaro E Eiras
- Laboratory of Technological Innovation of Vector Control, Department of Parasitology, Biological Science Institue, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
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17
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Mburu MM, Zembere K, Hiscox A, Banda J, Phiri KS, van den Berg H, Mzilahowa T, Takken W, McCann RS. Assessment of the Suna trap for sampling mosquitoes indoors and outdoors. Malar J 2019; 18:51. [PMID: 30795766 PMCID: PMC6387520 DOI: 10.1186/s12936-019-2680-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 02/14/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Entomological monitoring is important for public health because it provides data on the distribution, abundance and host-seeking behaviour of disease vectors. Various methods for sampling mosquitoes exist, most of which are biased towards, or specifically target, certain portions of a mosquito population. This study assessed the Suna trap, an odour-baited trap for sampling host-seeking mosquitoes both indoors and outdoors. METHODS Two separate field experiments were conducted in villages in southern Malawi. The efficiency of the Suna trap in sampling mosquitoes was compared to that of the human landing catch (HLC) indoors and outdoors and the Centers for Disease, Control and Prevention Light Trap (CDC-LT) indoors. Potential competition between two Suna traps during simultaneous use of the traps indoors and outdoors was assessed by comparing mosquito catch sizes across three treatments: one trap indoors only; one trap outdoors only; and one trap indoors and one trap outdoors used simultaneously at the same house. RESULTS The efficiency of the Suna trap in sampling female anophelines was similar to that of HLC indoors (P = 0.271) and HLC outdoors (P = 0.125), but lower than that of CDC-LT indoors (P = 0.001). Anopheline catch sizes in the Suna trap used alone indoors were similar to indoor Suna trap catch sizes when another Suna trap was simultaneously present outdoors (P = 0.891). Similarly, catch sizes of female anophelines with the Suna trap outdoors were similar to those that were caught outdoors when another Suna trap was simultaneously present indoors (P = 0.731). CONCLUSIONS The efficiency of the Suna trap in sampling mosquitoes was equivalent to that of the HLC. Whereas the CDC-LT was more efficient in collecting female anophelines indoors, the use of this trap outdoors is limited given the requirement of setting it next to an occupied bed net. As demonstrated in this research, outdoor collections are also essential because they provide data on the relative contribution of outdoor biting to malaria transmission. Therefore, the Suna trap could serve as an alternative to the HLC and the CDC-LT, because it does not require the use of humans as natural baits, allows standardised sampling conditions across sampling points, and can be used outdoors. Furthermore, using two Suna traps simultaneously indoors and outdoors does not interfere with the sampling efficiency of either trap, which would save a considerable amount of time, energy, and resources compared to setting the traps indoors and then outdoors in two consecutive nights.
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Affiliation(s)
- Monicah M Mburu
- College of Medicine, University of Malawi, Blantyre, Malawi. .,Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands.
| | | | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
| | - Jomo Banda
- College of Medicine, University of Malawi, Blantyre, Malawi.,MAC Communicable Diseases Action Centre, Blantyre, Malawi
| | - Kamija S Phiri
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
| | - Themba Mzilahowa
- College of Medicine, University of Malawi, Blantyre, Malawi.,MAC Communicable Diseases Action Centre, Blantyre, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
| | - Robert S McCann
- College of Medicine, University of Malawi, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
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18
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de Boer JG, Busula AO, Ten Berge J, van Dijk TS, Takken W. Does artemether-lumefantrine administration affect mosquito olfactory behaviour and fitness? Malar J 2019; 18:28. [PMID: 30691446 PMCID: PMC6350316 DOI: 10.1186/s12936-019-2646-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 01/11/2019] [Indexed: 11/24/2022] Open
Abstract
Background Artemisinin-based combination therapy (ACT) is the recommended treatment against uncomplicated Plasmodium falciparum infections, and ACT is widely used. It has been shown that gametocytes may be present after ACT and transmission to mosquitoes is still possible. Artemether–lumefantrine (AL) is a broadly used artemisinin-based combination medicine. Here, it is tested whether AL influences behaviour and fitness of Anopheles mosquitoes, which are the main vectors of P. falciparum. Results Dual-choice olfactometer and screenhouse experiments showed that skin odour of healthy human individuals obtained before, during and after AL-administration was equally attractive to Anopheles coluzzii and Anopheles gambiae sensu stricto, apart from a small (but significant) increase in mosquito response to skin odour collected 3 weeks after AL-administration. Anopheles coluzzii females fed on parasite-free blood supplemented with AL or on control-blood had similar survival, time until oviposition and number of eggs produced. Conclusions Based on the results, AL does not appear to influence malaria transmission through modification of vector mosquito olfactory behaviour or fitness. Extending these studies to Plasmodium-infected individuals and malaria mosquitoes with parasites are needed to further support this conclusion. Electronic supplementary material The online version of this article (10.1186/s12936-019-2646-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jetske G de Boer
- Laboratory of Entomology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. .,Netherlands Institute of Ecology, Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.
| | - Annette O Busula
- Laboratory of Entomology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.,International Centre of Insect Physiology and Ecology, P.O BOX 30772-00100 GPO, Nairobi, Kenya.,Kaimosi Friends University College, P.O BOX 385-50309, Kaimosi, Kenya
| | - Jet Ten Berge
- Laboratory of Entomology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Tessa S van Dijk
- Laboratory of Entomology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
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19
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Decision Making within the Built Environment as a Strategy for Mitigating the Risk of Malaria and Other Vector-Borne Diseases. BUILDINGS 2018. [DOI: 10.3390/buildings9010002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although significant efforts have been made to combat the spread of vector-borne diseases (VBDs), they still account for more than 17% of all infectious diseases. According to the World Health Organization (WHO), there were 216 million estimated cases in 2016. The efforts that resulted in these positive outcomes lack long-term financial sustainability because of the significant amount of funding involved. There is, therefore, a need for more cost-effective intervention. The authors contend that design decisions in the built environment can have a positive impact on the efforts directed at mitigating the risk of malaria in a more cost-effective manner. It is known that the built environment, through features such as openings, can propagate the spread of malaria. There have been some significant efforts directed at addressing this risk. This notwithstanding, an extensive review of closely related work established that built environment professionals have limited access to information on specific ways through which their design decisions can contribute to mitigating the risk of malaria. The validity of this hypothesis was tested through evaluating the opportunities for synergies in selected parts of East Africa. Secondary data derived from relevant urban health journals as well as repositories curated by leading health agencies such as WHO were synthesized and analyzed using a web of causation approach. The outcome of the analysis is a schema of primary and secondary source (risk) factors. The use of the web of causation approach revealed the existing factor-to-factor interactions that could have a reinforcing effect. This information was used to identify the critical linkages and interdependencies across different factors. The outcome of the analysis was mapped against risk factors that can be linked to decisions made during the six primary phases of the construction life cycle: Preliminary phase, conceptual design, detailed design, construction, facilities management, and end of life/disuse. A conceptual architecture for a decision support framework has been proposed and will be developed into a prototype in subsequent efforts.
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Abstract
The rapid spread of mosquito resistance to currently available insecticides, and the current lack of an efficacious malaria vaccine are among many challenges that affect large-scale efforts for malaria control. As goals of malaria elimination and eradication are put forth, new vector-control paradigms and tools and/or further optimization of current vector-control products are required to meet public health demands. Vector control remains the most effective measure to prevent malaria transmission and present gains against malaria mortality and morbidity may be maintained as long as vector-intervention strategies are sustained and adapted to underlying vector-related transmission dynamics. The following provides a brief overview of vector-control strategies and tools either in use or under development and evaluation that are intended to exploit key entomological parameters toward driving down transmission.
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Affiliation(s)
- Neil F Lobo
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556
| | - Nicole L Achee
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556
| | - John Greico
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556
| | - Frank H Collins
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556
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21
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Mmbando AS, Ngowo HS, Kilalangongono M, Abbas S, Matowo NS, Moore SJ, Okumu FO. Small-scale field evaluation of push-pull system against early- and outdoor-biting malaria mosquitoes in an area of high pyrethroid resistance in Tanzania. Wellcome Open Res 2017; 2:112. [PMID: 29568808 PMCID: PMC5840620 DOI: 10.12688/wellcomeopenres.13006.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2017] [Indexed: 12/22/2022] Open
Abstract
Background: Despite high coverage of indoor interventions like insecticide-treated nets, mosquito-borne infections persist, partly because of outdoor-biting, early-biting and insecticide-resistant vectors. Push-pull systems, where mosquitoes are repelled from humans and attracted to nearby lethal targets, may constitute effective complementary interventions. Methods: A partially randomized cross-over design was used to test efficacy of push-pull in four experimental huts and four local houses, in an area with high pyrethroid resistance in Tanzania. The push-pull system consisted of 1.1% or 2.2% w/v transfluthrin repellent dispensers and an outdoor lure-and-kill device (odour-baited mosquito landing box). Matching controls were set up without push-pull. Adult male volunteers collected mosquitoes attempting to bite them outdoors, but collections were also done indoors using exit traps in experimental huts and by volunteers in the local houses. The collections were done hourly (1830hrs-0730hrs) and mosquito catches compared between push-pull and controls.
An. gambiae s.l. and
An. funestus s.l. were assessed by PCR to identify sibling species, and ELISA to detect
Plasmodium falciparum and blood meal sources. Results: Push-pull in experimental huts reduced outdoor-biting for
An. arabiensis and
Mansonia species by 30% and 41.5% respectively. However, the reductions were marginal and insignificant for
An. funestus (12.2%; p>0.05) and
Culex (5%; p>0.05). Highest protection against all species occurred before 2200hrs. There was no significant difference in number of mosquitoes inside exit traps in huts with or without push-pull. In local households, push-pull significantly reduced indoor and outdoor-biting of
An. arabiensis by 48% and 25% respectively, but had no effect on other species. Conclusion: This push-pull system offered modest protection against outdoor-biting
An. arabiensis, without increasing indoor mosquito densities. Additional experimentation is required to assess how transfluthrin-based products affect mosquito blood-feeding and mortality in push-pull contexts. This approach, if optimised, could potentially complement existing malaria interventions even in areas with high pyrethroid resistance.
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Affiliation(s)
- Arnold S Mmbando
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,Univeristy of Basel, Basel, Switzerland
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania
| | - Masoud Kilalangongono
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania
| | - Said Abbas
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania
| | - Nancy S Matowo
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Sarah J Moore
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,Univeristy of Basel, Basel, Switzerland
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
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Abstract
Basic science holds enormous power for revealing the biological mechanisms of disease and, in turn, paving the way toward new, effective interventions. Recognizing this power, the 2011 Research Agenda for Malaria Eradication included key priorities in fundamental research that, if attained, could help accelerate progress toward disease elimination and eradication. The Malaria Eradication Research Agenda (malERA) Consultative Panel on Basic Science and Enabling Technologies reviewed the progress, continuing challenges, and major opportunities for future research. The recommendations come from a literature of published and unpublished materials and the deliberations of the malERA Refresh Consultative Panel. These areas span multiple aspects of the Plasmodium life cycle in both the human host and the Anopheles vector and include critical, unanswered questions about parasite transmission, human infection in the liver, asexual-stage biology, and malaria persistence. We believe an integrated approach encompassing human immunology, parasitology, and entomology, and harnessing new and emerging biomedical technologies offers the best path toward addressing these questions and, ultimately, lowering the worldwide burden of malaria.
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Saini RK, Orindi BO, Mbahin N, Andoke JA, Muasa PN, Mbuvi DM, Muya CM, Pickett JA, Borgemeister CW. Protecting cows in small holder farms in East Africa from tsetse flies by mimicking the odor profile of a non-host bovid. PLoS Negl Trop Dis 2017; 11:e0005977. [PMID: 29040267 PMCID: PMC5659797 DOI: 10.1371/journal.pntd.0005977] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 10/27/2017] [Accepted: 09/20/2017] [Indexed: 01/25/2023] Open
Abstract
Background For the first time, differential attraction of pathogen vectors to vertebrate animals is investigated for novel repellents which when applied to preferred host animals turn them into non-hosts thereby providing a new paradigm for innovative vector control. For effectively controlling tsetse flies (Glossina spp.), vectors of African trypanosomosis, causing nagana, repellents more powerful than plant derived, from a non-host animal the waterbuck, Kobus ellipsiprymnus defassa, have recently been identified. Here we investigate these repellents in the field to protect cattle from nagana by making cattle as unattractive as the buck. Methodology/Principal findings To dispense the waterbuck repellents comprising guaiacol, geranylacetone, pentanoic acid and δ-octalactone, (patent application) we developed an innovative collar-mounted release system for individual cattle. We tested protecting cattle, under natural tsetse challenge, from tsetse transmitted nagana in a large field trial comprising 1,100 cattle with repellent collars in Kenya for 24 months. The collars provided substantial protection to livestock from trypanosome infection by reducing disease levels >80%. Protected cattle were healthier, showed significantly reduced disease levels, higher packed cell volume and significantly increased weight. Collars >60% reduced trypanocide use, 72.7% increase in ownership of oxen per household and enhanced traction power (protected animals ploughed 66% more land than unprotected). Land under cultivation increased by 73.4%. Increase in traction power of protected animals reduced by 69.1% acres tilled by hand per household per ploughing season. Improved food security and household income from very high acceptance of collars (99%) motivated the farmers to form a registered community based organization promoting collars for integrated tsetse control and their commercialization. Conclusion/Significance Clear demonstration that repellents from un-preferred hosts prevent contact between host and vector, thereby preventing disease transmission: a new paradigm for vector control. Evidence that deploying water buck repellents converts cattle into non-hosts for tsetse flies—‘cows in waterbuck clothing’. We investigated the potential of non-host odors from un-preferred animals, i.e. not fed upon, related to cattle, the waterbuck (Kobus ellipsiprymnus defassa) which are common in tsetse habitats for their efficacy to protect cattle from tsetse flies that transmit nagana to cattle in Africa. The identified waterbuck repellent compounds comprising of geranylacetone, pentanoic acid, guaiacol and δ-octalactone (patent application) were dispensed on cattle (hosts) using innovative repellent dispensers that individual cattle wear encircling their necks. This study, which is the first of its kind, shows that the waterbuck repellent compounds can provide substantial protection to cattle from trypanosome infections by reducing disease levels >80% in protected animals. Thus, by mimicking the odor profile of waterbucks, ‘cows in waterbuck clothing’ are essentially turned into non-hosts for tsetse flies and thus provide a new paradigm for innovative vector control. In our trial, protection of cattle with the repellent collars resulted in considerably improved food security as a result of significant reduction in trypanocide use, improved health of the protected animals which enhanced traction power with more land being brought under cultivation. Farmers’ perceptions of the repellent collars are very positive and socioeconomic studies indicate that adoption potential is extremely high.
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Affiliation(s)
- Rajinder K. Saini
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Pestinix-International Pest & Vector Control Specialists, Nairobi, Kenya
- * E-mail: ,
| | - Benedict O. Orindi
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- African Population and Health Research Center (APHRC), Nairobi, Kenya
| | - Norber Mbahin
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Africa Union–Interafrican Bureau for Animal Resources (AU-IBAR), Nairobi, Kenya
| | - John A. Andoke
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Peter N. Muasa
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - David M. Mbuvi
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Caroline M. Muya
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | | | - Christian W. Borgemeister
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Center for Development Research (ZEF), University of Bonn, Bonn, Germany
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24
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Mburu MM, Mweresa CK, Omusula P, Hiscox A, Takken W, Mukabana WR. 2-Butanone as a carbon dioxide mimic in attractant blends for the Afrotropical malaria mosquitoes Anopheles gambiae and Anopheles funestus. Malar J 2017; 16:351. [PMID: 28836977 PMCID: PMC5571623 DOI: 10.1186/s12936-017-1998-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/20/2017] [Indexed: 11/21/2022] Open
Abstract
Background Most odour baits designed to attract host-seeking mosquitoes contain carbon dioxide (CO2), which enhances trap catches, given its role as a mosquito flight activator. However, the use of CO2 is expensive and logistically demanding for prolonged area-wide use. Methods This study explored the possibility of replacing organically-produced CO2 with 2-butanone in odour blends targeting host-seeking malaria mosquitoes. During semi-field and field experiments MM-X traps were baited with a human odour mimic (MB5 blend) plus CO2 or 2-butanone at varying concentrations. Unbaited traps formed a control. The attraction of Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus to these differently baited traps was measured and mean catch sizes were compared to determine whether 2-butanone could form a viable replacement for CO2 for these target species. Results Under semi-field conditions significantly more female An. gambiae mosquitoes were attracted to a reference attractant blend (MB5 + CO2) compared to MB5 without CO2 (P < 0.001), CO2 alone (P < 0.001), or a trap without a bait (P < 0.001). Whereas MB5 + CO2 attracted significantly more mosquitoes than its variants containing MB5 plus different dilutions of 2-butanone (P = 0.001), the pure form (99.5%) and the 1.0% dilution of 2-butanone gave promising results. In the field mean indoor catches of wild female An. gambiae s.l. in traps containing MB5 + CO2 (5.07 ± 1.01) and MB5 + 99.5% 2-butanone (3.10 ± 0.65) did not differ significantly (P = 0.09). The mean indoor catches of wild female An. funestus attracted to traps containing MB5 + CO2 (3.87 ± 0.79) and MB5 + 99.5% 2-butanone (3.37 ± 0.70) were also similar (P = 0.635). Likewise, the mean outdoor catches of An. gambiae and An. funestus associated with MB5 + CO2 (1.63 ± 0.38 and 0.53 ± 0.17, respectively) and MB5 + 99.5% 2-butanone (1.33 ± 0.32 and 0.40 ± 0.14, respectively) were not significantly different (P = 0.544 and P = 0.533, respectively). Conclusion These results demonstrate that 2-butanone can serve as a good replacement for CO2 in synthetic blends of attractants designed to attract host-seeking An. gambiae s.l. and An. funestus mosquitoes. This development underscores the possibility of using odour-baited traps (OBTs) for monitoring and surveillance as well as control of malaria vectors and potentially other mosquito species.
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Affiliation(s)
- Monicah M Mburu
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya.,School of Biological Sciences, University of Nairobi, P.O. Box 30197, Nairobi, 00100, Kenya.,Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Collins K Mweresa
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya.,School of Biological and Physical Sciences, Jaramogi Oginga Odinga University of Science and Technology, P.O. Box 210, Bondo, 40601, Kenya.,Science for Health, P.O. Box 44970, Nairobi, 00100, Kenya
| | - Philemon Omusula
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya.,International Centre for Aids Care and Treatment Program, Ministry of Health, Jaramogi Oginga Odinga Teaching and Referral Hospital, P.O. Box 849, Kisumu, 50100, Kenya
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Wolfgang R Mukabana
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, Nairobi, 00100, Kenya. .,School of Biological Sciences, University of Nairobi, P.O. Box 30197, Nairobi, 00100, Kenya. .,Science for Health, P.O. Box 44970, Nairobi, 00100, Kenya.
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25
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Spitzen J, Koelewijn T, Mukabana WR, Takken W. Effect of insecticide-treated bed nets on house-entry by malaria mosquitoes: The flight response recorded in a semi-field study in Kenya. Acta Trop 2017; 172:180-185. [PMID: 28495403 DOI: 10.1016/j.actatropica.2017.05.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/04/2017] [Accepted: 05/05/2017] [Indexed: 11/17/2022]
Abstract
Insecticide-treated nets are currently a major tool to reduce malaria transmission. Their level of repellency affects contact of the mosquito with the net, but may also influence the mosquito's entry into the house. The response of host-seeking malaria mosquitoes approaching the eave of an experimental house was recorded within a large screen house. We compared entry- and exit rates in relation to the presence in the house of different insecticide-treated bed nets (ITNs) with an untreated net. Mosquitoes were lured towards the house by dispensing a synthetic host-odour blend from within the net in the house. Complementary WHO bioassays revealed that the treated nets caused high knock-down- and mortality responses to the Anopheles gambiae sensu stricto strain tested. The proportion of mosquitoes that came into view of the cameras and subsequently entered the house did not differ between treated nets and the untreated net. Treated nets did not affect proportions of mosquitoes that exited the house and departed from view around the eave. However, the percentage of house-leaving and re-entering mosquitoes when an insecticide- treated net was present, was lower than in the presence of an untreated net. Our results indicated that there was no spatial repellent effect from pyrethroid-treated nets that influences house-entry at eave level. It is argued that the toxic effect of treated bed nets resulted in a reduced number of mosquitoes re-entering the house, which could thereby affect malaria transmission in neighbouring, unprotected houses.
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Affiliation(s)
- Jeroen Spitzen
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands.
| | - Teun Koelewijn
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands.
| | - W Richard Mukabana
- International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya; Science for Health, P.O. Box 44970-00100, Nairobi, Kenya.
| | - Willem Takken
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands.
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26
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Muema JM, Bargul JL, Njeru SN, Onyango JO, Imbahale SS. Prospects for malaria control through manipulation of mosquito larval habitats and olfactory-mediated behavioural responses using plant-derived compounds. Parasit Vectors 2017; 10:184. [PMID: 28412962 PMCID: PMC5392979 DOI: 10.1186/s13071-017-2122-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 03/29/2017] [Indexed: 11/14/2022] Open
Abstract
Malaria presents an overwhelming public health challenge, particularly in sub-Saharan Africa where vector favourable conditions and poverty prevail, potentiating the disease burden. Behavioural variability of malaria vectors poses a great challenge to existing vector control programmes with insecticide resistance already acquired to nearly all available chemical compounds. Thus, approaches incorporating plant-derived compounds to manipulate semiochemical-mediated behaviours through disruption of mosquito olfactory sensory system have considerably gained interests to interrupt malaria transmission cycle. The combination of push-pull methods and larval control have the potential to reduce malaria vector populations, thus minimising the risk of contracting malaria especially in resource-constrained communities where access to synthetic insecticides is a challenge. In this review, we have compiled information regarding the current status of knowledge on manipulation of larval ecology and chemical-mediated behaviour of adult mosquitoes with plant-derived compounds for controlling mosquito populations. Further, an update on the current advancements in technologies to improve longevity and efficiency of these compounds for field applications has been provided.
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Affiliation(s)
- Jackson M Muema
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.
| | - Joel L Bargul
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.,Molecular Biology and Bioinformatics Unit, International Centre of Insect Physiology and Ecology, P.O. Box 30772-00100, Nairobi, Kenya
| | - Sospeter N Njeru
- Department of Medicine, Faculty of Health Sciences, Kisii University, P.O. Box 408-40200, Kisii, Kenya.,Present Address: Fritz Lipmann Institute (FLI) - Leibniz Institute of Aging Research, D-07745, Jena, Germany
| | - Joab O Onyango
- Department of Chemical Science and Technology, Technical University of Kenya, P.O. Box 52428-00200, Nairobi, Kenya
| | - Susan S Imbahale
- Department of Applied and Technical Biology, Technical University of Kenya, P.O. Box 52428-00200, Nairobi, Kenya
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27
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Hiscox A, Homan T, Mweresa CK, Maire N, Di Pasquale A, Masiga D, Oria PA, Alaii J, Leeuwis C, Mukabana WR, Takken W, Smith TA. Mass mosquito trapping for malaria control in western Kenya: study protocol for a stepped wedge cluster-randomised trial. Trials 2016; 17:356. [PMID: 27460054 PMCID: PMC4962350 DOI: 10.1186/s13063-016-1469-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 06/30/2016] [Indexed: 11/17/2022] Open
Abstract
Background Increasing levels of insecticide resistance as well as outdoor, residual transmission of malaria threaten the efficacy of existing vector control tools used against malaria mosquitoes. The development of odour-baited mosquito traps has led to the possibility of controlling malaria through mass trapping of malaria vectors. Through daily removal trapping against a background of continued bed net use it is anticipated that vector populations could be suppressed to a level where continued transmission of malaria will no longer be possible. Methods/design A stepped wedge cluster-randomised trial design was used for the implementation of mass mosquito trapping on Rusinga Island, western Kenya (the SolarMal project). Over the course of 2 years (2013–2015) all households on the island were provided with a solar-powered mosquito trapping system. A continuous health and demographic surveillance system combined with parasitological surveys three times a year, successive rounds of mosquito monitoring and regular sociological studies allowed measurement of intervention outcomes before, during and at completion of the rollout of traps. Data collection continued after achieving mass coverage with traps in order to estimate the longer term effectiveness of this novel intervention. Solar energy was exploited to provide electric light and mobile phone charging for each household, and the impacts of these immediate tangible benefits upon acceptability of and adherence to the use of the intervention are being measured. Discussion This study will be the first to evaluate whether the principle of solar-powered mass mosquito trapping could be an effective tool for elimination of malaria. If proven to be effective, this novel approach to malaria control would be a valuable addition to the existing strategies of long-lasting insecticide-treated nets and case management. Sociological studies provide a knowledge base for understanding the usage of this novel tool. Trial registration Trialregister.nl: NTR3496 – SolarMal. Registered on 20 June 2012. Electronic supplementary material The online version of this article (doi:10.1186/s13063-016-1469-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexandra Hiscox
- Laboratory of Entomology, Wageningen University Research Centre, Wageningen, The Netherlands.
| | - Tobias Homan
- Laboratory of Entomology, Wageningen University Research Centre, Wageningen, The Netherlands
| | - Collins K Mweresa
- Human Health Division, International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Nicolas Maire
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Aurelio Di Pasquale
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Daniel Masiga
- Human Health Division, International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Prisca A Oria
- Human Health Division, International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,Knowledge, Technology and Innovation Group, Wageningen University and Research Centre, Wageningen, The Netherlands
| | - Jane Alaii
- Human Health Division, International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,Context Factor Solutions, Nairobi, Kenya
| | - Cees Leeuwis
- Knowledge, Technology and Innovation Group, Wageningen University and Research Centre, Wageningen, The Netherlands
| | | | - Willem Takken
- Laboratory of Entomology, Wageningen University Research Centre, Wageningen, The Netherlands
| | - Thomas A Smith
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
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28
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Mweresa CK, Mukabana WR, Omusula P, Otieno B, Van Loon JJA, Takken W. Enhancing Attraction of African Malaria Vectors to a Synthetic Odor Blend. J Chem Ecol 2016; 42:508-16. [PMID: 27349651 DOI: 10.1007/s10886-016-0711-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 04/02/2016] [Accepted: 05/18/2016] [Indexed: 10/21/2022]
Abstract
The deployment of odor-baited tools for sampling and controlling malaria vectors is limited by a lack of potent synthetic mosquito attractants. A synthetic mixture of chemical compounds referred to as "the Mbita blend" (MB) was shown to attract as many host-seeking malaria mosquitoes as attracted to human subjects. We hypothesized that this effect could be enhanced by adding one or more attractive compounds to the blend. We tested changes in the capability of MB (ammonia + L-lactic acid + tetradecanoic acid +3-methyl-1-butanol + carbon dioxide) to attract host-seeking malaria mosquitoes by addition of selected dilutions of butyl-2-methylbutanoate (1:10,000), 2-pentadecanone (1:100), 1-dodecanol (1:10,000), and butan-1-amine (1:10,000,000). The experiments were conducted in semi-field enclosures and in a village in western Kenya. In semi-field enclosures, the attraction of Anopheles gambiae sensu stricto females to MB-baited traps was not enhanced by adding butyl-2-methylbutanoate. There was, however, an increase in the proportion of An. gambiae caught in traps containing MB augmented with the selected dilutions of butan-1-amine, 2-pentadecanone, and 1-dodecanol. When tested in the village, addition of butan-1-amine to MB enhanced catches of female An. gambiae sensu lato, An. funestus, and Culex mosquitoes. 1-Dodecanol increased attraction of An. gambiae s.l. to the MB, while addition of 2-pentadecanone improved trap catches of An. funestus and Culex mosquitoes. This study demonstrates the possibility of enhancing synthetic odor blends for trapping the malarial mosquitoes An. gambiae s.l. and An. funestus, as well as some culicine species. The findings provide promising results for the optimization and utilization of synthetic attractants for sampling and controlling major disease vectors.
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Affiliation(s)
- Collins K Mweresa
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, GPO Nairobi, Kenya.
| | - Wolfgang R Mukabana
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, GPO Nairobi, Kenya
- School of Biological Sciences, University of Nairobi, P.O. Box 30197, GPO Nairobi, Kenya
| | - Philemon Omusula
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, GPO Nairobi, Kenya
- International Centre for Aids Care and Treatment Program, Ministry of Health, Jaramogi Oginga Odinga Teaching and Referral Hospital, P.O. Box 849 -, Kisumu, 50100, Kenya
| | - Bruno Otieno
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, GPO Nairobi, Kenya
| | - Joop J A Van Loon
- Laboratory of Entomology, Wageningen University and Research Centre, P.O. Boxs 16, 6700, AA, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research Centre, P.O. Boxs 16, 6700, AA, Wageningen, The Netherlands
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He X, He ZB, Zhang YJ, Zhou Y, Xian PJ, Qiao L, Chen B. Genome-wide identification and characterization of odorant-binding protein (OBP) genes in the malaria vector Anopheles sinensis (Diptera: Culicidae). INSECT SCIENCE 2016; 23:366-376. [PMID: 26970073 DOI: 10.1111/1744-7917.12333] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/03/2016] [Indexed: 06/05/2023]
Abstract
Anopheles sinensis is a major malaria vector. Insect odorant-binding proteins (OBPs) may function in the reception of odorants in the olfactory system. The classification and characterization of the An. sinensis OBP genes have not been systematically studied. In this study, 64 putative OBP genes were identified at the whole-genome level of An. sinensis based on the comparison between OBP conserved motifs, PBP_GOBP, and phylogenetic analysis with An. gambiae OBPs. The characterization of An. sinensis OBPs, including the motif's conservation, gene structure, genomic organization and classification, were investigated. A new gene, AsOBP73, belonging to the Plus-C subfamily, was identified with the support of transcript and conservative motifs. These An. sinensis OBP genes were classified into three subfamilies with 37, 15 and 12 genes in the subfamily Classic, Atypical and Plus-C, respectively. The genomic organization of An. sinensis OBPs suggests a clustered distribution across nine different scaffolds. Eight genes (OBP23-28, OBP63-64) might originate from a single gene through a series of historic duplication events at least before divergence of Anopheles, Culex and Aedes. The microsynteny analyses indicate a very high synteny between An. sinensis and An. gambiae OBPs. OBP70 and OBP71 earlier classified under Plus-C in An. gambiae are recognized as belonging to the group Obp59a of the Classic subfamily, and OBP69 earlier classified under Plus-C has been moved to the Atypical subfamily in this study. The study established a basic information frame for further study of the OBP genes in insects as well as in An. sinensis.
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Affiliation(s)
- Xiu He
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Zheng-Bo He
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Yu-Juan Zhang
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Yong Zhou
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Peng-Jie Xian
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Liang Qiao
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Bin Chen
- Institute of Entomology and Molecular Biology, College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
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Spitzen J, Koelewijn T, Mukabana WR, Takken W. Visualization of house-entry behaviour of malaria mosquitoes. Malar J 2016; 15:233. [PMID: 27108961 PMCID: PMC4843208 DOI: 10.1186/s12936-016-1293-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 04/14/2016] [Indexed: 12/02/2022] Open
Abstract
Background Malaria mosquitoes often blood feed indoors on human hosts. The mosquitoes predominantly enter houses via open eaves. Host-seeking is odour-driven, and finding a host depends on the quality of the odour plume and whether the route towards the host is free of obstructions. Little is known about in-flight behaviour of mosquitoes during house entry. This semi-field study visualizes mosquito house entry in three dimensions (3D) and offers new insights for optimizing vector control interventions. Methods The approach and house entry of Anopheles gambiae sensu stricto was studied in a semi-field set-up using video-recorded flight tracks and 3D analysis. Behavioural parameters of host-seeking female mosquitoes were visualized with respect to their position relative to the eave as well as whether a mosquito would enter or not. Host odour was standardized using an attractive synthetic blend in addition to CO2. The study was conducted in western Kenya at the Thomas Odhiambo Campus of the International Centre of Insect Physiology and Ecology, Mbita. Results The majority of host-seeking An. gambiae approached a house with a flight altitude at eave level, arriving within a horizontal arc of 180°. Fifty-five per cent of mosquitoes approaching a house did not enter or made multiple attempts before passing through the eave. During approach, mosquitoes greatly reduced their speed and the flight paths became more convoluted. As a result, mosquitoes that passed through the eave spent more than 80 % of the observed time within 30 cm of the eave. Mosquitoes that exited the eave departed at eave level and followed the edge of the roof (12.5 %) or quickly re-entered after exiting (9.6 %). Conclusions The study shows that host-seeking mosquitoes, when entering a house, approach the eave in a wide angle to the house at eave level. Less than 25 % of approaching mosquitoes entered the house without interruption, whereas 12.5 % of mosquitoes that had entered left the house again within the time of observation. Advances in tracking techniques open a new array of questions that can now be answered to improve household interventions that combat malaria transmission. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1293-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jeroen Spitzen
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
| | - Teun Koelewijn
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands
| | - W Richard Mukabana
- International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya.,School of Biological Sciences, University of Nairobi, P.O. Box 30197 GPO, Nairobi, Kenya
| | - Willem Takken
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands
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The use of Aedes aegypti larvae attractants to enhance the effectiveness of larvicides. Parasitol Res 2016; 115:2185-90. [DOI: 10.1007/s00436-016-4960-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 02/17/2016] [Indexed: 10/22/2022]
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Menger DJ, Omusula P, Wouters K, Oketch C, Carreira AS, Durka M, Derycke JL, Loy DE, Hahn BH, Mukabana WR, Mweresa CK, van Loon JJA, Takken W, Hiscox A. Eave Screening and Push-Pull Tactics to Reduce House Entry by Vectors of Malaria. Am J Trop Med Hyg 2016; 94:868-78. [PMID: 26834195 DOI: 10.4269/ajtmh.15-0632] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/31/2015] [Indexed: 11/07/2022] Open
Abstract
Long-lasting insecticidal nets and indoor residual spraying have contributed to a decline in malaria over the last decade, but progress is threatened by the development of physiological and behavioral resistance of mosquitoes against insecticides. Acknowledging the need for alternative vector control tools, we quantified the effects of eave screening in combination with a push-pull system based on the simultaneous use of a repellent (push) and attractant-baited traps (pull). Field experiments in western Kenya showed that eave screening, whether used in combination with an attractant-baited trap or not, was highly effective in reducing house entry by malaria mosquitoes. The magnitude of the effect varied for different mosquito species and between two experiments, but the reduction in house entry was always considerable (between 61% and 99%). The use of outdoor, attractant-baited traps alone did not have a significant impact on mosquito house entry but the high number of mosquitoes trapped outdoors indicates that attractant-baited traps could be used for removal trapping, which would enhance outdoor as well as indoor protection against mosquito bites. As eave screening was effective by itself, addition of a repellent was of limited value. Nevertheless, repellents may play a role in reducing outdoor malaria transmission in the peridomestic area.
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Affiliation(s)
- David J Menger
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Philemon Omusula
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Karlijn Wouters
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Charles Oketch
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Ana S Carreira
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Maxime Durka
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Jean-Luc Derycke
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Dorothy E Loy
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Beatrice H Hahn
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Wolfgang R Mukabana
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Collins K Mweresa
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Joop J A van Loon
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands; International Centre of Insect Physiology and Ecology, Nairobi, Kenya; Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal; Devan-Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Maia, Portugal; Devan Chemicals NV, Ronse, Belgium; Utexbel NV, Ronse, Belgium; Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; School of Biological Sciences, University of Nairobi, Nairobi, Kenya
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The Human-Baited Double Net Trap: An Alternative to Human Landing Catches for Collecting Outdoor Biting Mosquitoes in Lao PDR. PLoS One 2015; 10:e0138735. [PMID: 26381896 PMCID: PMC4575072 DOI: 10.1371/journal.pone.0138735] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 09/01/2015] [Indexed: 11/30/2022] Open
Abstract
Estimating the exposure of individuals to mosquito-borne diseases is a key measure used to evaluate the success of vector control operations. The gold standard is to use human landing catches where mosquitoes are collected off the exposed limbs of human collectors. This is however an unsatisfactory method since it potentially exposes individuals to a range of mosquito-borne diseases. In this study several sampling methods were compared to find a method that is representative of the human-biting rate outdoors, but which does not expose collectors to mosquito-borne infections. The sampling efficiency of four odour-baited traps were compared outdoors in rural Lao PDR; the human-baited double net (HDN) trap, CDC light trap, BG sentinel trap and Suna trap. Subsequently the HDN, the best performing trap, was compared directly with human landing catches (HLC), the ‘gold standard’, for estimating human-biting rates. HDNs collected 11–44 times more mosquitoes than the other traps, with the exception of the HLC. The HDN collected similar numbers of Anopheles (Rate Ratio, RR = 1.16, 95% Confidence Intervals, 95% CI = 0.61–2.20) and Culex mosquitoes (RR = 1.26, 95% CI = 0.74–2.17) as HLC, but under-estimated the numbers of Aedes albopictus (RR = 0.45, 95% CI = 0.27–0.77). Simpson’s index of diversity was 0.845 (95% CI 0.836–0.854) for the HDN trap and 0.778 (95% CI 0.769–0.787) for HLC, indicating that the HDN collected a greater diversity of mosquito species than HLC. Both HLC and HDN can distinguish between low and high biting rates and are crude ways to measure human-biting rate. The HDN is a simple and cheap method to estimate the human-biting rate outdoors without exposing collectors to mosquito bites.
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Verhulst NO, Bakker JW, Hiscox A. Modification of the Suna Trap for Improved Survival and Quality of Mosquitoes in Support of Epidemiological Studies. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2015; 31:223-232. [PMID: 26375903 DOI: 10.2987/moco-31-03-223-232.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Monitoring adult mosquito populations provides information that is critical for assessing risk of vector-borne disease transmission. The recently developed Suna trap was found to be a very effective trap when baited with an attractive odor blend. A modification of this trap was tested to improve its function as a tool for monitoring mosquito populations, including Anopheles coluzzii (An. gambiae sensu stricto molecular form M), Aedes aegypti, and Culex pipiens. The modified Suna trap (Suna-M) was altered by changing the position of the catch bag and the inclusion of a holding chamber in attempts to increase trapping efficacy and enhance the survival of mosquitoes. Each adaptation was tested in a dual-choice setup in a climate-controlled room against the original Suna trap and against 4 standard monitoring methods: the BG-sentinel (BGS), Centers for Disease Control and Prevention (CDC) light trap, Mosquito Magnet X (MM-X) trap, and human landing catch (HLC). No differences in trapping efficacy were observed between the original Suna trap and modified version; however, a version in which the funnel was extended with a box and supplemented with moistened cotton wool increased mosquito survival from 6.5% to 78.0% over 24 h. The HLC and BGS trap outperformed the Suna-M trap, whereas the MM-X and commonly used CDC light trap performed significantly less well than the Suna-M trap in the dual-choice setup. The performance of the Suna-M trap equaled the performance of the original Suna trap and could therefore be used for monitoring purposes. Although the HLC and BGS trap achieved higher catch sizes, the Suna trap has the advantage that it is standardized, does not place humans at risk, and is weather resistant. Field studies should be conducted to confirm that the Suna-M trap, baited with the odor blend, is an efficient and standardized tool to measure both indoor and outdoor disease transmission risk for a range of vector-borne diseases.
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Affiliation(s)
- Niels O Verhulst
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, the Netherlands
| | - Julian W Bakker
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, the Netherlands
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, the Netherlands
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Obermayr U, Ruther J, Bernier UR, Rose A, Geier M. Evaluation of a Push-Pull Approach for Aedes aegypti (L.) Using a Novel Dispensing System for Spatial Repellents in the Laboratory and in a Semi-Field Environment. PLoS One 2015; 10:e0129878. [PMID: 26115365 PMCID: PMC4482593 DOI: 10.1371/journal.pone.0129878] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/15/2015] [Indexed: 11/26/2022] Open
Abstract
The increase in insecticide resistant mosquito populations necessitates the exploration of novel vector control intervention measures. Push-pull strategies for insect control have been successful when used in integrated crop pest management. Through the combinatory use of deterring and attracting stimuli, the abundance of insect pests can be changed in a given area. A push-pull strategy might also significantly reduce human-vector contacts and augment existing mosquito control strategies, e.g. through the combination of an attractive trapping system and a potent spatial repellent. Our approach includes the BG-Sentinel (BGS) trap in combination with catnip oil (Nepeta cataria), a known spatial repellent for Aedes aegypti. To impart a deterrent effect on mosquitoes at a distance, a homogenous and continuous dispersal of volatile repellent compounds is crucial. We have developed a repellent dispensing system that is easy to use and provides a homogenous dispersal of repellent in an air curtain. The use of five 9 V fans and custom-made repellent sachets containing 10% catnip essential oil created a repellent loaded air curtain that provided coverage of an area of 2 m2 (1.2 x 1.65 m). Air was sampled at four different heights in the curtain and analysed via thermal desorption (TD) and consecutive gas chromatography-mass spectrometry (GC-MS). Nepetalactone, the main constituent of the oil, was detected in air at a concentration range of 80 to 100 μg/m3 and the amounts were comparable at all four sampling positions. When a human volunteer was sitting behind the repellent curtain and a BGS trap was installed in front of the curtain in laboratory push-pull trials, Ae. aegypti landing collections decreased significantly by 50% compared to repellent-free controls. However, in a semi-field environment, comparable protective effects could not be achieved and further research on suitable repellent concentrations for outdoor implementation will be required.
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Affiliation(s)
- Ulla Obermayr
- Biogents AG, Weissenburgstrasse 22, D-93055, Regensburg, Germany
| | - Joachim Ruther
- Universitaet Regensburg, Institute of Zoology, Universitaetsstrasse 31, D-93053, Regensburg, Germany
| | - Ulrich R. Bernier
- USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, 1600 SW 23 Dr., Gainesville, Florida, 32608, United States of America
| | - Andreas Rose
- Biogents AG, Weissenburgstrasse 22, D-93055, Regensburg, Germany
| | - Martin Geier
- Biogents AG, Weissenburgstrasse 22, D-93055, Regensburg, Germany
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Wagman JM, Grieco JP, Bautista K, Polanco J, Briceño I, King R, Achee NL. The field evaluation of a push-pull system to control malaria vectors in northern Belize, Central America. Malar J 2015; 14:184. [PMID: 25925395 PMCID: PMC4425932 DOI: 10.1186/s12936-015-0692-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/05/2015] [Indexed: 11/23/2022] Open
Abstract
Background Campaigns for the continued reduction and eventual elimination of malaria may benefit from new and innovative vector control tools. One novel approach being considered uses a push-pull strategy, whereby spatial repellents are used in combination with outdoor baited traps. The desired effect is the behavioural manipulation of mosquito populations to elicit movement of vectors away from people and into traps. Methods Here, a prototype push-pull intervention was evaluated using an experimental hut methodology to test proof-of-principle for the strategy against two natural vector populations, Anopheles albimanus and Anopheles vestitipennis, in Belize, Central America. A Latin square study design was used to compare mosquito entry into experimental huts and outdoor traps across four different experimental conditions: 1) control, with no interventions; 2) pull, utilizing only outdoor traps; 3) push, utilizing only an indoor spatial repellent; and 4) push-pull, utilizing both interventions simultaneously. Results For An. vestitipennis, the combined use of an indoor repellent and outdoor baited traps reduced average nightly mosquito hut entry by 39% (95% CI: [0.37 – 0.41]) as compared to control and simultaneously increased the nightly average densities of An. vestitipennis captured in outdoor baited traps by 48% (95% CI: [0.22 – 0.74]), compared to when no repellent was used. Against An. albimanus, the combined push-pull treatment similarly reduced hut entry, by 54% (95% CI: [0.40 – 0.68]) as compared to control; however, the presence of a repellent indoors did not affect overall outdoor trap catch densities for this species. Against both anopheline species, the combined intervention did not further reduce mosquito hut entry compared to the use of repellent alone. Conclusions The prototype intervention evaluated here clearly demonstrated that push-pull strategies have potential to reduce human-vector interactions inside homes by reducing mosquito entry, and highlighted the possibility for the strategy to simultaneously decrease human-vector interactions outside of homes by increasing baited trap collections. However, the variation in effect on different vectors demonstrates the need to characterize the underlying behavioral ecology of target mosquitoes in order to drive local optimization of the intervention. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0692-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joseph M Wagman
- Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.
| | - John P Grieco
- College of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN, 46556, USA.
| | - Kim Bautista
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Jorge Polanco
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Ireneo Briceño
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Russell King
- Ministry of Health, East Block Independence Plaza, Belmopan, Belize.
| | - Nicole L Achee
- College of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN, 46556, USA.
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Menger DJ, Omusula P, Holdinga M, Homan T, Carreira AS, Vandendaele P, Derycke JL, Mweresa CK, Mukabana WR, van Loon JJA, Takken W. Field evaluation of a push-pull system to reduce malaria transmission. PLoS One 2015; 10:e0123415. [PMID: 25923114 PMCID: PMC4414508 DOI: 10.1371/journal.pone.0123415] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/18/2015] [Indexed: 11/24/2022] Open
Abstract
Malaria continues to place a disease burden on millions of people throughout the tropics, especially in sub-Saharan Africa. Although efforts to control mosquito populations and reduce human-vector contact, such as long-lasting insecticidal nets and indoor residual spraying, have led to significant decreases in malaria incidence, further progress is now threatened by the widespread development of physiological and behavioural insecticide-resistance as well as changes in the composition of vector populations. A mosquito-directed push-pull system based on the simultaneous use of attractive and repellent volatiles offers a complementary tool to existing vector-control methods. In this study, the combination of a trap baited with a five-compound attractant and a strip of net-fabric impregnated with micro-encapsulated repellent and placed in the eaves of houses, was tested in a malaria-endemic village in western Kenya. Using the repellent delta-undecalactone, mosquito house entry was reduced by more than 50%, while the traps caught high numbers of outdoor flying mosquitoes. Model simulations predict that, assuming area-wide coverage, the addition of such a push-pull system to existing prevention efforts will result in up to 20-fold reductions in the entomological inoculation rate. Reductions of such magnitude are also predicted when mosquitoes exhibit a high resistance against insecticides. We conclude that a push-pull system based on non-toxic volatiles provides an important addition to existing strategies for malaria prevention.
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Affiliation(s)
- David J. Menger
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
- * E-mail:
| | - Philemon Omusula
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, GPO Nairobi, Kenya
| | - Maarten Holdinga
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
| | - Tobias Homan
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
| | - Ana S. Carreira
- CIEPQPF, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, 3030–790, Coimbra, Portugal
- Devan—Micropolis, Tecmaia-Parque da Ciência e Tecnologia da Maia, Rua Eng. Frederico Ulrich, 2650, 4470–605, Maia, Portugal
| | | | | | - Collins K. Mweresa
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, GPO Nairobi, Kenya
| | - Wolfgang Richard Mukabana
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, GPO Nairobi, Kenya
- School of Biological Sciences, University of Nairobi, P.O. Box 30197–00100, GPO Nairobi, Kenya
| | - Joop J. A. van Loon
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
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Busula AO, Takken W, Loy DE, Hahn BH, Mukabana WR, Verhulst NO. Mosquito host preferences affect their response to synthetic and natural odour blends. Malar J 2015; 14:133. [PMID: 25889954 PMCID: PMC4381365 DOI: 10.1186/s12936-015-0635-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/01/2015] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The anthropophilic malaria mosquito Anopheles gambiae sensu stricto (hereafter termed Anopheles gambiae) primarily takes blood meals from humans, whereas its close sibling Anopheles arabiensis is more opportunistic. Previous studies have identified several compounds that play a critical role in the odour-mediated behaviour of An. gambiae. This study determined the effect of natural and synthetic odour blends on mosquitoes with different host preferences to better understand the host-seeking behaviour of mosquitoes and the potential of synthetic odour blends for standardized monitoring. METHODS Odour blends were initially tested for their attractiveness to An. gambiae and An. arabiensis in a semi-field system with MM-X traps baited with natural and synthetic odours. Natural host odours were collected from humans, cows and chickens. The synthetic odour blends consisted of three or five previously identified compounds released with carbon dioxide. These studies were continued under natural conditions where odour blends were tested outdoors to determine their effect on species with different host preferences. RESULTS In the semi-field experiments, human odour attracted significantly higher numbers of both mosquito species. However, An. arabiensis was also attracted to cow and chicken odours, which confirms its opportunistic behaviour. A five-component synthetic blend was highly attractive to both mosquito species. In the field, the synthetic odour blend caught significantly more An. funestus than traps baited with human odour, while no difference was found for An. arabiensis. Catches of An. arabiensis and Culex spp. contained large numbers of blood-fed mosquitoes, mostly from cows, which indicates that these mosquitoes had fed outdoors. CONCLUSIONS Different odour baits elicit varying responses among mosquito species. Synthetic odour blends are highly effective for trapping mosquitoes; however, not all mosquitoes respond equally to the same odour blend. Combining fermenting molasses with synthetic blends in a trap represents the most effective tool to catch blood-fed mosquitoes outside houses, which is essential for understanding outdoor malaria transmission.
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Affiliation(s)
- Annette O Busula
- International Centre of Insect Physiology and Ecology, PO Box 30772-00100 GPO, Nairobi, Kenya. .,Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
| | - Willem Takken
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
| | - Dorothy E Loy
- Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, PA, 19104-6076, USA.
| | - Beatrice H Hahn
- Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, 3610 Hamilton Walk, Philadelphia, PA, 19104-6076, USA.
| | - Wolfgang R Mukabana
- International Centre of Insect Physiology and Ecology, PO Box 30772-00100 GPO, Nairobi, Kenya. .,School of Biological Sciences, University of Nairobi, PO Box 30197-00100 GPO, Nairobi, Kenya.
| | - Niels O Verhulst
- Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
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