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Javed N, Paradkar PN, Bhatti A. An overview of technologies available to monitor behaviours of mosquitoes. Acta Trop 2024; 258:107347. [PMID: 39103110 DOI: 10.1016/j.actatropica.2024.107347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/30/2024] [Accepted: 07/31/2024] [Indexed: 08/07/2024]
Abstract
Mosquito-borne diseases such as malaria, dengue, Zika, and chikungunya cause significant morbidity and mortality globally, resulting in over 600,000 deaths from malaria and around 36,000 deaths from dengue each year, with millions of people infected annually, leading to substantial economic losses. The existing mosquito control measures, such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), helped to reduce the infections. However, mosquito-borne diseases are still among the deadliest diseases, forcing us to improve the existing control methods and look for alternative methods simultaneously. Advanced monitoring techniques, including remote sensing, and geographic information systems (GIS) have significantly enhanced the efficiency and effectiveness of mosquito control measures. Mosquitoes' behavioural traits, such as locomotion, blood-feeding, and fertility are the key determinants of disease transmission and epidemiology. Technological advancements, such as high-resolution cameras, infrared imaging, and artificial intelligence (AI) driven object detection models, including groundbreaking convolutional neural networks, have provided efficient and precise options to monitor various mosquito behaviours, including locomotion, oviposition, fertility, and host-seeking. However, they are not commonly employed in mosquito-based research. This review highlights the novel and significant advancements in behaviour-monitoring tools, mostly from the last decade, due to cutting-edge video monitoring technology and artificial intelligence. These advancements can offer enhanced accuracy, efficiency, and the ability to quickly process large volumes of data, enabling detailed behavioural analysis over extended periods and large sample sizes, unlike traditional manual methods prone to human error and labour-intensive. The use of behaviour-assaying techniques can support or replace existing monitoring techniques and directly contribute to improving control measures by providing more accurate and real-time data on mosquito activity patterns and responses to interventions. This enhanced understanding can help establish the role of behavioural changes in improving epidemiological models, making them more precise and dynamic. As a result, mosquito management strategies can become more adaptive and responsive, leading to more effective and targeted interventions. Ultimately, this will reduce disease transmission and significantly improve public health outcomes.
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Affiliation(s)
- Nouman Javed
- Institute for Intelligent Systems Research and Innovation, Deakin University, Geelong, Victoria 3216 Australia.
| | - Prasad N Paradkar
- CSIRO Health & Biosecurity, Australian Centre for Disease Preparedness, Geelong, Victoria 3220 Australia
| | - Asim Bhatti
- Institute for Intelligent Systems Research and Innovation, Deakin University, Geelong, Victoria 3216 Australia
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Qureshi YM, Voloshin V, Towers CE, Covington JA, Towers DP. Double vision: 2D and 3D mosquito trajectories can be as valuable for behaviour analysis via machine learning. Parasit Vectors 2024; 17:282. [PMID: 38956638 PMCID: PMC11218242 DOI: 10.1186/s13071-024-06356-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 06/15/2024] [Indexed: 07/04/2024] Open
Abstract
BACKGROUND Mosquitoes are carriers of tropical diseases, thus demanding a comprehensive understanding of their behaviour to devise effective disease control strategies. In this article we show that machine learning can provide a performance assessment of 2D and 3D machine vision techniques and thereby guide entomologists towards appropriate experimental approaches for behaviour assessment. Behaviours are best characterised via tracking-giving a full time series of information. However, tracking systems vary in complexity. Single-camera imaging yields two-component position data which generally are a function of all three orthogonal components due to perspective; however, a telecentric imaging setup gives constant magnification with respect to depth and thereby measures two orthogonal position components. Multi-camera or holographic techniques quantify all three components. METHODS In this study a 3D mosquito mating swarm dataset was used to generate equivalent 2D data via telecentric imaging and a single camera at various imaging distances. The performance of the tracking systems was assessed through an established machine learning classifier that differentiates male and non-male mosquito tracks. SHAPs analysis has been used to explore the trajectory feature values for each model. RESULTS The results reveal that both telecentric and single-camera models, when placed at large distances from the flying mosquitoes, can produce equivalent accuracy from a classifier as well as preserve characteristic features without resorting to more complex 3D tracking techniques. CONCLUSIONS Caution should be exercised when employing a single camera at short distances as classifier balanced accuracy is reduced compared to that from 3D or telecentric imaging; the trajectory features also deviate compared to those from the other datasets. It is postulated that measurement of two orthogonal motion components is necessary to optimise the accuracy of machine learning classifiers based on trajectory data. The study increases the evidence base for using machine learning to determine behaviours from insect trajectory data.
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Affiliation(s)
| | - Vitaly Voloshin
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, E1 4NS, UK
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Parker JEA, Kakilla C, Nelwin K, Kroner C, Logan R, Ismail HM, Towers C, Manjurano A, Towers D, McCall PJ. Video-tracked Anopheles arabiensis entry and exit behaviour at washed and damaged pyrethroid-treated bednets. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231165. [PMID: 39076790 PMCID: PMC11285834 DOI: 10.1098/rsos.231165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 04/03/2024] [Accepted: 04/05/2024] [Indexed: 07/31/2024]
Abstract
Insecticide-treated nets (ITNs) are the most effective method for malaria prevention in Africa. Using near-infrared video tracking in a laboratory environment, we recorded and assessed bednet entry and exit by a northern Tanzanian population of Anopheles arabiensis at a human-occupied untreated net and a PermaNet® 2.0 ITN. Both had 12 holes, each 10 cm in diameter, punctured at specific locations, and the ITN was washed 20 times to further simulate the wear and tear of ageing. Washing reduced the insecticide content of ITNs by 61%, which then showed similar rates to the untreated nets for net entry (39% entered untreated net and 41% entered ITN; p = 0.84) and exit (37% and 43%, respectively; p = 0.67). Regardless of treatment, approximately 40% of mosquitoes entered nets within 20 s of first appearing in the field of view and reached the volunteer's skin within 5 s of entering the net. Mortality rates post-exposure were significantly higher (p = 0.048) at ITNs (26.6%; 95% CI 13.4%-39.7%) than at untreated controls (6.4%; 95% CI 1.8%-14.6%). The washed and aged ITN provided little additional personal protection for the sleeper over an untreated net. Simple adjustments to materials and design that could extend the effective lifespan of ITNs are discussed.
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Affiliation(s)
- J. E. A. Parker
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - C. Kakilla
- National Institute of Medical Research, Mwanza, Tanzania
| | - K. Nelwin
- National Institute of Medical Research, Mwanza, Tanzania
| | - C. Kroner
- School of Engineering, University of Warwick, Coventry, UK
| | - R. Logan
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Parasitology Department, Heidelberg University Hospital, Heidelberg, Germany
| | - H. M. Ismail
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - C. Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - A. Manjurano
- National Institute of Medical Research, Mwanza, Tanzania
| | - D. Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - P. J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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Akoton R, Sovegnon PM, Djihinto OY, Medjigbodo AA, Agonhossou R, Saizonou HM, Tchigossou GM, Atoyebi SM, Tossou E, Zeukeng F, Lagnika HO, Mousse W, Adegnika AA, Djouaka R, Djogbénou LS. Vectorial competence, insecticide resistance in Anopheles funestus and operational implications for malaria vector control strategies in Benin Republic. Malar J 2023; 22:385. [PMID: 38129880 PMCID: PMC10740250 DOI: 10.1186/s12936-023-04815-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
The primary reason for the failure of malaria vector control across endemic regions is the widespread insecticide resistance observed in Anopheles vectors. The most dominant African vectors of malaria parasites are Anopheles gambiae and Anopheles funestus mosquitoes. These species often exhibit divergent behaviours and adaptive changes underscoring the importance of deploying active and effective measures in their control. Unlike An. gambiae, An. funestus mosquitoes are poorly studied in Benin Republic. However, recent reports indicated that An. funestus can adapt and colonize various ecological niches owing to its resistance against insecticides and adaptation to changing breeding habitats. Unfortunately, scientific investigations on the contribution of An. funestus to malaria transmission, their susceptibility to insecticide and resistance mechanism developed are currently insufficient for the design of better control strategies. In an attempt to gather valuable information on An. funestus, the present review examines the progress made on this malaria vector species in Benin Republic and highlights future research perspectives on insecticide resistance profiles and related mechanisms, as well as new potential control strategies against An. funestus. Literature analysis revealed that An. funestus is distributed all over the country, although present in low density compared to other dominant malaria vectors. Interestingly, An. funestus is being found in abundance during the dry seasons, suggesting an adaptation to desiccation. Among the An. funestus group, only An. funestus sensu stricto (s.s.) and Anopheles leesoni were found in the country with An. funestus s.s. being the most abundant species. Furthermore, An. funestus s.s. is the only one species in the group contributing to malaria transmission and have adapted biting times that allow them to bite at dawn. In addition, across the country, An. funestus were found resistant to pyrethroid insecticides used for bed nets impregnation and also resistant to bendiocarb which is currently being introduced in indoor residual spraying formulation in malaria endemic regions. All these findings highlight the challenges faced in controlling this malaria vector. Therefore, advancing the knowledge of vectorial competence of An. funestus, understanding the dynamics of insecticide resistance in this malaria vector, and exploring alternative vector control measures, are critical for sustainable malaria control efforts in Benin Republic.
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Affiliation(s)
- Romaric Akoton
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin.
- Fondation Pour la Recherche Scientifique (FORS), Cotonou, Benin.
| | - Pierre Marie Sovegnon
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Oswald Y Djihinto
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Adandé A Medjigbodo
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Romuald Agonhossou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
- Fondation Pour la Recherche Scientifique (FORS), Cotonou, Benin
| | - Helga M Saizonou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | | | - Seun M Atoyebi
- Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Oyo, Nigeria
| | - Eric Tossou
- International Institute of Tropical Agriculture, Cotonou, Benin
| | - Francis Zeukeng
- Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, Buea, Cameroon
| | - Hamirath O Lagnika
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Wassiyath Mousse
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Ayola Akim Adegnika
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
- Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany
| | | | - Luc S Djogbénou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Abomey-Calavi, Benin
- Regional Institute of Public Health, University of Abomey-Calavi, Ouidah, Benin
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Abbott AJ, Matope A, Jones J, Voloshin V, Towers CE, Towers D, McCall PJ. Insecticidal roof barriers mounted on untreated bed nets can be as effective against Anopheles gambiae as regular insecticide-treated bed nets. Sci Rep 2023; 13:22080. [PMID: 38086842 PMCID: PMC10716170 DOI: 10.1038/s41598-023-48499-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
Barrier bednets (BBnets), regular bednets with a vertical insecticidal panel to target mosquitoes above the bednet roof, where they are most active, have the potential to improve existing Insecticidal Treated Bednets (ITNs), by reducing the quantity of insecticide required per net, reducing the toxic risks to those using the net, potentially increasing insecticide choice. We evaluated the performance of PermaNet 3.0 (P3) and untreated (Ut) bed nets with and without pyrethroid and piperonyl butoxide roof barriers in killing pyrethroid-resistant and susceptible Anopheles gambiae, simultaneously video-recording mosquito flight tracks. Bioassay results showed that treated roof barriers, particularly the longitudinal P3 barrier (P3L) could be an effective addition to a bed net: P3 + P3L were consistently significantly more effective than the reference P3 bednet while performance of untreated nets could be raised to equal that of the reference P3 following the addition of a P3 barrier. The BBnet's potential to augment existing bednets and enhance their performance is considered.
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Affiliation(s)
- Anthony J Abbott
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Agnes Matope
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Jeff Jones
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Vitaly Voloshin
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Catherine E Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - David Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Philip J McCall
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.
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Kampango A, Smith TA, Abílio AP, Machoe EA, Matusse JF, Pinto J, McCall PJ. The Shockwè trap: a human-baited exposure-free device for surveillance and behaviour studies of anthropophilic vectors. Wellcome Open Res 2023; 8:455. [PMID: 38644931 PMCID: PMC11031644 DOI: 10.12688/wellcomeopenres.19963.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2023] [Indexed: 04/23/2024] Open
Abstract
Background: The human biting rate (MBR) and entomological inoculation rate (EIR) are common parameters routinely used to measure the risk of malaria transmission. Both parameters can be estimated using human landing catches (HLC). Although it is considered the gold-standard, HLC puts collectors at higher risk of infection with mosquito-transmitted pathogens. Methods: A novel exposure-free host-seeking mosquito electrocution trap, the Shockwè trap (SHK), was developed and its efficiency for monitoring mosquito community composition and abundance was compared with human landing catches (HLC) as the gold-standard. Field experiments were performed in Massavasse village, southern Mozambique. Simultaneous indoor and outdoor collections of nocturnal host-seeking mosquitoes were carried out using the SHK and HLC methods. The relative sampling efficiency of SHK was estimated as the ratio of the numbers of mosquitoes caught in SHK compared HLC. Proportionality and density-dependence between SHK and HLC catches were estimated by mean of Bayesian regression approaches. Results: A total of 69,758 and 27,359 host-seeking mosquitoes comprising nineteen species and four genera, were collected by HLC and SHK respectively. In general, SHK and HLC sampled similar numbers of mosquito species, with the exceptions of the least common species Aedes sudanensis, Ae. subargenteus, and Coquillettidia versicolor that were caught only by HLC. The relative sampling efficiency and proportionality between SHK and matched HLC catches varied greatly between species and collection site. However, all mosquitoes collected by SHK were unfed, confirming the Shockwè trap design's performance and reliability as a successful mosquito exposure free sampling approach. Conclusions: Results demonstrate that SHK is a safe and reliable human-exposure free device for monitoring the occurrence of a wide range of mosquito, including major malaria and arboviruses vector species. However, improvements are needed to increase its sampling efficiency for less abundant mosquito species.
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Affiliation(s)
- Ayubo Kampango
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - Thomas A. Smith
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Ana Paula Abílio
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - Elias Alberto Machoe
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - Júlio Francisco Matusse
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - João Pinto
- Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Lisbon, Portugal
| | - Philip J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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Gleave K, Guy A, Mechan F, Emery M, Murphy A, Voloshin V, Towers CE, Towers D, Ranson H, Foster GM, McCall PJ. Impacts of dual active-ingredient bed nets on the behavioural responses of pyrethroid resistant Anopheles gambiae determined by room-scale infrared video tracking. Malar J 2023; 22:132. [PMID: 37088828 PMCID: PMC10122874 DOI: 10.1186/s12936-023-04548-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 03/31/2023] [Indexed: 04/25/2023] Open
Abstract
BACKGROUND The success of insecticide treated bed nets (ITNs) for malaria vector control in Africa relies on the behaviour of various species of Anopheles. Previous research has described mosquito behavioural alterations resulting from widespread ITN coverage, which could result in a decrease in net efficacy. Here, behaviours were compared including timings of net contact, willingness to refeed and longevity post-exposure to two next-generation nets, PermaNet® 3.0 (P3 net) and Interceptor® G2 (IG2 net) in comparison with a standard pyrethroid-only net (Olyset Net™ (OL net)) and an untreated net. METHODS Susceptible and resistant Anopheles gambiae mosquitoes were exposed to the nets with a human volunteer host in a room-scale assay. Mosquito movements were tracked for 2 h using an infrared video system, collecting flight trajectory, spatial position and net contact data. Post-assay, mosquitoes were monitored for a range of sublethal insecticide effects. RESULTS Mosquito net contact was focused predominantly on the roof for all four bed nets. A steep decay in activity was observed for both susceptible strains when P3 net and OL net were present and with IG2 net for one of the two susceptible strains. Total mosquito activity was higher around untreated nets than ITNs. There was no difference in total activity, the number, or duration, of net contact, between any mosquito strain, with similar behaviours recorded in susceptible and resistant strains at all ITNs. OL net, P3 net and IG2 net all killed over 90% of susceptible mosquitoes 24 h after exposure, but this effect was not seen with resistant mosquitoes where mortality ranged from 16 to 72%. All treated nets reduced the willingness of resistant strains to re-feed when offered blood 1-h post-exposure, with a more pronounced effect seen with P3 net and OL net than IG2 net. CONCLUSION These are the first results to provide an in-depth description of the behaviour of susceptible and resistant Anopheles gambiae strains around next-generation bed nets using a room-scale tracking system to capture multiple behaviours. These results indicate that there is no major difference in behavioural responses between mosquito strains of differing pyrethroid susceptibility when exposed to these new ITNs under the experimental conditions used.
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Affiliation(s)
- Katherine Gleave
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Amy Guy
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Frank Mechan
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Mischa Emery
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Annabel Murphy
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | | | - David Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - Hilary Ranson
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Geraldine M Foster
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Philip J McCall
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK.
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Inferring the epidemiological benefit of indoor vector control interventions against malaria from mosquito data. Nat Commun 2022; 13:3862. [PMID: 35790746 PMCID: PMC9256631 DOI: 10.1038/s41467-022-30700-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/11/2022] [Indexed: 12/03/2022] Open
Abstract
The cause of malaria transmission has been known for over a century but it is still unclear whether entomological measures are sufficiently reliable to inform policy decisions in human health. Decision-making on the effectiveness of new insecticide-treated nets (ITNs) and the indoor residual spraying of insecticide (IRS) have been based on epidemiological data, typically collected in cluster-randomised control trials. The number of these trials that can be conducted is limited. Here we use a systematic review to highlight that efficacy estimates of the same intervention may vary substantially between trials. Analyses indicate that mosquito data collected in experimental hut trials can be used to parameterize mechanistic models for Plasmodium falciparum malaria and reliably predict the epidemiological efficacy of quick-acting, neuro-acting ITNs and IRS. Results suggest that for certain types of ITNs and IRS using this framework instead of clinical endpoints could support policy and expedite the widespread use of novel technologies. Estimating the effectiveness of malaria vector control interventions has typically relied on resource-intensive cluster randomised trials. Here, the authors estimate changes in malaria prevalence using entomological data from experimental hut trials, which may provide an alternative route to approval of interventions in some situations.
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Sutcliffe JF, Yin S. Effects of indoor air movement and ambient temperature on mosquito (Anopheles gambiae) behaviour around bed nets: implications for malaria prevention initiatives. Malar J 2021; 20:427. [PMID: 34717652 PMCID: PMC8557611 DOI: 10.1186/s12936-021-03957-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/18/2021] [Indexed: 11/10/2022] Open
Abstract
Background Until recently, relatively little research has been done on how mosquitoes behave around the occupied bed net in the indoor environment. This has been partly remedied in the last few years through laboratory and field studies, most of these using video methods and mosquito flight tracking. Despite these recent advances, understanding of the mosquito-bed net environment system, and the principles that underlie mosquito behaviour within it, is limited. This project aimed to further understand this system by studying the effects of gently moving air (such as might be introduced through room design to make the indoor environment more comfortable and conducive to ITN use) and warmer vs. cooler ambient conditions on mosquito activity around ITNs and other bed nets. Methods The activity of colonized female Anopheles gambiae around an occupied untreated bed net set up in a mosquito-proof tent in a large laboratory space was recorded under different ambient conditions using a laser detection-video recording system. Conditions tested were ‘cool’ (23–25 °C) and ‘warm’ (27–30 °C) air temperatures and the presence or absence of a cross-flow produced by a small central processing unit (CPU) fan pointed at the side of the net so that it produced a ‘low-’ or ‘high-’ speed cross-draught (approx. 0.1 and 0.4 m/s, respectively). Near-net activity in recordings was measured using video image analysis. Results In cool, still air conditions, more than 80% of near-net activity by An. gambiae occurred on the net roof. Introduction of the low-speed or high-speed cross-draught resulted in an almost total drop off in roof activity within 1 to 2 min and, in the case of the high-speed cross-draught, a complementary increase in activity on the net side. In warm, still conditions, near-net activity appeared to be lower overall than in cool, still air conditions and to be relatively less focussed on the roof. Introduction of the high-speed cross-draught in warm conditions resulted in a decrease in roof activity and increase in side activity though neither effect was statistically significant. Conclusions Results are interpreted in terms of the flow of the stimulatory odour plume produced by the net occupant which, consistent with established principles of fluid dynamics, appears to rise quickly and remain more intact above the net occupant in cool, still air than in warm, still air. Cross-draught effects are ascribed to the changes they cause in the flow of the host odour plume as opposed to mosquito flight directly. The implications of these results for house designs that promote indoor air movement, on bed net design, and on other vector control measures are discussed. How mosquitoes approach a net is influenced both by indoor temperature and ventilation and their interaction. This system is in need of further study. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03957-y.
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Affiliation(s)
- James F Sutcliffe
- Dept. Biology, Trent University, Peterborough, ON, Canada. .,Entomology Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA.
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Lissenden N, Kont MD, Essandoh J, Ismail HM, Churcher TS, Lambert B, Lenhart A, McCall PJ, Moyes CL, Paine MJI, Praulins G, Weetman D, Lees RS. Review and Meta-Analysis of the Evidence for Choosing between Specific Pyrethroids for Programmatic Purposes. INSECTS 2021; 12:insects12090826. [PMID: 34564266 PMCID: PMC8465213 DOI: 10.3390/insects12090826] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/24/2021] [Accepted: 09/11/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary A group of insecticides, called pyrethroids, are the main strategy for controlling the mosquito vectors of malaria. Pyrethroids are used in all insecticide-treated bednets, and many indoor residual spray programmes (in which insecticides are sprayed on the interior walls of houses). There are different types of pyrethroids within the class (e.g., deltamethrin and permethrin). Across the world, mosquitoes are showing signs of resistance to the pyrethroids, such as reduced mortality following contact. However, it is unclear if this resistance is uniform across the pyrethroid class (i.e., if a mosquito is resistant to deltamethrin, whether it is resistant to permethrin at the same level). In addition, it is not known if switching between different pyrethroids can be used to effectively maintain mosquito control when resistance to a single pyrethroid has been detected. This review examined the evidence from molecular studies, resistance testing from laboratory and field data, and mosquito behavioural assays to answer these questions. The evidence suggested that in areas where pyrethroid resistance exists, different mortality seen between the pyrethroids is not necessarily indicative of an operationally relevant difference in control performance, and there is no reason to rotate between common pyrethroids (i.e., deltamethrin, permethrin, and alpha-cypermethrin) as an insecticide resistance management strategy. Abstract Pyrethroid resistance is widespread in malaria vectors. However, differential mortality in discriminating dose assays to different pyrethroids is often observed in wild populations. When this occurs, it is unclear if this differential mortality should be interpreted as an indication of differential levels of susceptibility within the pyrethroid class, and if so, if countries should consider selecting one specific pyrethroid for programmatic use over another. A review of evidence from molecular studies, resistance testing with laboratory colonies and wild populations, and mosquito behavioural assays were conducted to answer these questions. Evidence suggested that in areas where pyrethroid resistance exists, different results in insecticide susceptibility assays with specific pyrethroids currently in common use (deltamethrin, permethrin, α-cypermethrin, and λ-cyhalothrin) are not necessarily indicative of an operationally relevant difference in potential performance. Consequently, it is not advisable to use rotation between these pyrethroids as an insecticide-resistance management strategy. Less commonly used pyrethroids (bifenthrin and etofenprox) may have sufficiently different modes of action, though further work is needed to examine how this may apply to insecticide resistance management.
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Affiliation(s)
- Natalie Lissenden
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Mara D. Kont
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - John Essandoh
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Hanafy M. Ismail
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Thomas S. Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - Ben Lambert
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - Audrey Lenhart
- U.S. Centers for Disease Control and Prevention, Entomology Branch, Division of Parasitic Diseases and Malaria, Atlanta, GA 30329, USA;
| | - Philip J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | | | - Mark J. I. Paine
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Giorgio Praulins
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Rosemary S. Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
- Correspondence: ; Tel.: +44-(0)-151-705-3344
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11
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Skovmand O, Dang DM, Tran TQ, Bossellman R, Moore SJ. From the factory to the field: considerations of product characteristics for insecticide-treated net (ITN) bioefficacy testing. Malar J 2021; 20:363. [PMID: 34488778 PMCID: PMC8422710 DOI: 10.1186/s12936-021-03897-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 08/26/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated nets (ITNs) undergo a series of tests to obtain listing by World Health Organization (WHO) Prequalification. These tests characterize the bioefficacy, physical and chemical properties of the ITN. ITN procurers assume that product specifications relate to product performance. Here, ITN test methods and their underlying assumptions are discussed from the perspective of the ITN manufacturing process and product characteristics. METHODS Data were extracted from WHO Pesticide Evaluation Scheme (WHOPES) meeting reports from 2003 to 2017, supplemented with additional chemical analysis to critically evaluate ITNs bioassays with a focus on sampling, washing and wash resistance, and bioefficacy testing. Production methods for ITNs and their impact on testing outcomes are described. RESULTS AND RECOMMENDATIONS ITNs are not homogenous products. They vary within panels and between the sides and the roof. Running tests of wash resistance using a before/after tests on the same sample or band within a net reduces test variability. As mosquitoes frequently interact with ITN roofs, additional sampling of the roof when evaluating ITNs is advisable because in nets where roof and sides are of the same material, the contribution of roof sample (20-25%) to the average is less than the tolerance for the specification (25%). Mosquito mortality data cannot be reliably used to evaluate net surface concentration to determine regeneration time (RT) and resistance to washing as nets may regenerate beyond the insecticide concentrations needed to kill 100% of susceptible mosquitoes. Chemical assays to quantify surface concentration are needed. The Wash Resistance Index (WRI) averaged over the first four washes is only informative if the product has a log linear loss rate of insecticide. Using a WRI that excludes the first wash off gives more reliable results. Storage conditions used for product specifications are lower than those encountered under product shipping and storage that may exceed 50 °C, and should be reconsidered. Operational monitoring of new ITNs and linking observed product performance, such as bioefficacy after 2 or 3 years of use, with product characteristics, such as WRI, will aid the development of more robust test methods and product specifications for new products coming to market.
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Affiliation(s)
- Ole Skovmand
- Intelligent Insect Control, Castelnau le Lez, France.
| | | | | | | | - Sarah J Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.
- Department of Epidemiology and Public Health, Vector Biology Unit, Swiss Tropical and Public Health Institute, Socinstrasse, 57, 4002, Basel, Switzerland.
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland.
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12
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Hinze A, Lantz J, Hill SR, Ignell R. Mosquito Host Seeking in 3D Using a Versatile Climate-Controlled Wind Tunnel System. Front Behav Neurosci 2021; 15:643693. [PMID: 33776664 PMCID: PMC7991727 DOI: 10.3389/fnbeh.2021.643693] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/15/2021] [Indexed: 12/25/2022] Open
Abstract
Future anthropogenic climate change is predicted to impact sensory-driven behaviors. Building on recent improvements in computational power and tracking technology, we have developed a versatile climate-controlled wind tunnel system, in which to study the effect of climate parameters, including temperature, precipitation, and elevated greenhouse gas levels, on odor-mediated behaviors in insects. To establish a baseline for future studies, we here analyzed the host-seeking behavior of the major malaria vector mosquito, Anopheles gambiae sensu strico, to human odor and carbon dioxide (CO2), under tightly controlled climatic conditions, and isolated from potential background contamination by the presence of an experimenter. When presented with a combination of human foot odor and CO2 (case study I), mosquitoes engaged in faster crosswind flight, spent more time in the filamentous odor plume and targeted the odor source more successfully. In contrast, female An. gambiae s. s. presented with different concentrations of CO2 alone, did not display host-seeking behavior (case study II). These observations support previous findings on the role of human host-associated cues in host seeking and confirm the role of CO2 as a synergist, but not a host-seeking cue on its own. Future studies are aimed at investigating the effect of climate change on odor-mediated behavior in mosquitoes and other insects. Moreover, the system will be used to investigate detection and processing of olfactory information in various behavioral contexts, by providing a fine-scale analysis of flight behavior.
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Affiliation(s)
- Annika Hinze
- Disease Vector Group, Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Jörgen Lantz
- Jörgen Lantz Engineering Consulting Firm, Alnarp, Sweden
| | - Sharon R Hill
- Disease Vector Group, Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.,Max Planck Centre Next Generation Chemical Ecology, Uppsala, Sweden
| | - Rickard Ignell
- Disease Vector Group, Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.,Max Planck Centre Next Generation Chemical Ecology, Uppsala, Sweden
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13
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Yan J, Gangoso L, Ruiz S, Soriguer R, Figuerola J, Martínez-de la Puente J. Understanding host utilization by mosquitoes: determinants, challenges and future directions. Biol Rev Camb Philos Soc 2021; 96:1367-1385. [PMID: 33686781 DOI: 10.1111/brv.12706] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 02/24/2021] [Accepted: 02/24/2021] [Indexed: 12/29/2022]
Abstract
Mosquito host utilization is a key factor in the transmission of vector-borne pathogens given that it greatly influences host-vector contact rates. Blood-feeding patterns of mosquitoes are not random, as some mosquitoes feed on particular species and/or individuals more than expected by chance. Mosquitoes use a number of cues including visual, olfactory, acoustic, and thermal stimuli emitted by vertebrate hosts to locate and identify their blood meal sources. Thus, differences in the quality/intensity of the released cues may drive host selection by mosquitoes at both inter- and intra-specific levels. Such patterns of host selection by mosquitoes in space and time can be structured by factors related to mosquitoes (e.g. innate host preference, behavioural plasticity), to hosts (e.g. emission of host-seeking cues, host availability) or to both (e.g. pathogen infection). In this study, we review current evidence, from phenomena to mechanisms, of how these factors influence host utilization by mosquitoes. We also review the methodologies commonly used in this research field and identify the major challenges for future studies. To bridge the knowledge gaps, we propose improvements to strengthen traditional approaches and the use of a functional trait-based approach to infer mosquito host utilization in natural communities.
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Affiliation(s)
- Jiayue Yan
- Doñana Biological Station, Spanish National Research Council (EBD-CSIC), C/Americo Vespucio 26, Seville, 41092, Spain.,Illinois Natural History Survey, University of Illinois, 1816 S Oak St., Champaign, IL, 61821, U.S.A
| | - Laura Gangoso
- Doñana Biological Station, Spanish National Research Council (EBD-CSIC), C/Americo Vespucio 26, Seville, 41092, Spain.,Department of Biodiversity, Ecology and Evolution, Faculty of Biology, Complutense University of Madrid, C/José Antonio Novais 2, Madrid, 28040, Spain
| | - Santiago Ruiz
- CIBER of Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos 3-5, Madrid, 28029, Spain.,Service of Mosquito Control, Diputación Provincial de Huelva, Ctra. Hospital Infanta Elena s/n, Huelva, 21007, Spain
| | - Ramón Soriguer
- Doñana Biological Station, Spanish National Research Council (EBD-CSIC), C/Americo Vespucio 26, Seville, 41092, Spain.,CIBER of Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos 3-5, Madrid, 28029, Spain
| | - Jordi Figuerola
- Doñana Biological Station, Spanish National Research Council (EBD-CSIC), C/Americo Vespucio 26, Seville, 41092, Spain.,CIBER of Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos 3-5, Madrid, 28029, Spain
| | - Josué Martínez-de la Puente
- Doñana Biological Station, Spanish National Research Council (EBD-CSIC), C/Americo Vespucio 26, Seville, 41092, Spain.,CIBER of Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos 3-5, Madrid, 28029, Spain.,Department of Parasitology, Faculty of Pharmacy, University of Granada (UGR), Campus Universitario de Cartuja, Granada, 18.071, Spain
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14
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Hall ML, McCall P, Towers CE, Towers DP. Improved three-dimensional localization of multiple small objects in close proximity in digital holography. APPLIED OPTICS 2021; 60:A285-A295. [PMID: 33690380 DOI: 10.1364/ao.404432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/17/2020] [Indexed: 06/12/2023]
Abstract
Using intensity gradient- or sparsity-based focus metrics, the ability to accurately localize the three-dimensional (3D) position of a small object in a digital holographic reconstruction of a large field of view is hindered in the presence of multiple nearby objects. A more accurate alternative method for 3D localization, based on evaluation of the complex reconstructed volume, is proposed. Simulations and experimental data demonstrate a reduction in depth positional error for single objects and a notably improved axial resolution of multiple objects in close proximity.
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15
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Jones J, Murray GPD, McCall PJ. A minimal 3D model of mosquito flight behaviour around the human baited bed net. Malar J 2021; 20:24. [PMID: 33413370 PMCID: PMC7792054 DOI: 10.1186/s12936-020-03546-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/12/2020] [Indexed: 02/08/2023] Open
Abstract
Background Advances in digitized video-tracking and behavioural analysis have enabled accurate recording and quantification of mosquito flight and host-seeking behaviours, facilitating development of individual (agent) based models at much finer spatial scales than previously possible. Methods Quantified behavioural parameters were used to create a novel virtual testing model, capable of accurately simulating indoor flight behaviour by a virtual population of host-seeking mosquitoes as they interact with and respond to simulated stimuli from a human-occupied bed net. The model is described, including base mosquito behaviour, state transitions, environmental representation and host stimulus representation. Results In the absence of a bed net and human host bait, flight distribution of the model population was relatively uniform throughout the arena. Introducing an unbaited untreated bed net induced a change in distribution with an increase in landing events on the net surface, predominantly on the sides of the net. Adding the presence of a simulated human bait dramatically impacted flight distribution patterns, exploratory foraging and, the number and distribution of landing positions on the net, which were determined largely by the orientation of the human within. The model replicates experimental results with free-flying living mosquitoes at human-occupied bed nets, where contact occurs predominantly on the top surface of the net. This accuracy is important as it quantifies exposure to the lethal insecticide residues that may be unique to the net roof (or theoretically any other surface). Number of net contacts and height of contacts decreased with increasing attractant dispersal noise. Conclusions Results generated by the model are an accurate representation of actual mosquito behaviour recorded at and around a human-occupied bed net in untreated and insecticide-treated nets. This fine-grained model is highly flexible and has significant potential for in silico screening of novel bed net designs, potentially reducing time and cost and accelerating the deployment of new and more effective tools for protecting against malaria in sub-Saharan Africa.
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Affiliation(s)
- Jeff Jones
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK
| | - Gregory P D Murray
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK
| | - Philip J McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK.
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16
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Voloshin V, Kröner C, Seniya C, Murray GPD, Guy A, Towers CE, McCall PJ, Towers DP. Diffuse retro-reflective imaging for improved video tracking of mosquitoes at human baited bednets. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191951. [PMID: 32537200 PMCID: PMC7277285 DOI: 10.1098/rsos.191951] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 04/06/2020] [Indexed: 05/09/2023]
Abstract
Robust imaging techniques for tracking insects have been essential tools in numerous laboratory and field studies on pests, beneficial insects and model systems. Recent innovations in optical imaging systems and associated signal processing have enabled detailed characterization of nocturnal mosquito behaviour around bednets and improvements in bednet design, a global essential for protecting populations against malaria. Nonetheless, there remain challenges around ease of use for large-scale in situ recordings and extracting data reliably in the critical areas of the bednet where the optical signal is attenuated. Here, we introduce a retro-reflective screen at the back of the measurement volume, which can simultaneously provide diffuse illumination, and remove optical alignment issues while requiring only one-sided access to the measurement space. The illumination becomes significantly more uniform, although noise removal algorithms are needed to reduce the effects of shot noise, particularly across low-intensity bednet regions. By systematically introducing mosquitoes in front of and behind the bednet in laboratory experiments, we are able to demonstrate robust tracking in these challenging areas. Overall, the retro-reflective imaging set-up delivers mosquito segmentation rates in excess of 90% compared to less than 70% with backlit systems.
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Affiliation(s)
- Vitaly Voloshin
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Christian Kröner
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | | | | | - Amy Guy
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | | | - Philip J. McCall
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - David P. Towers
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
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17
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Hughes A, Foster GM, Guy A, Matope A, Abe M, Towers D, McCall PJ. Quantifying late-stage host-seeking behaviour of Anopheles gambiae at the insecticidal net interface using a baited-box bioassay. Malar J 2020; 19:140. [PMID: 32264900 PMCID: PMC7140563 DOI: 10.1186/s12936-020-03213-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 03/28/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated nets (ITNs) are losing efficacy against pyrethroid-resistant malaria vector populations throughout Africa. Safeguarding bed net efficacy, vital for effective malaria control, requires greater knowledge of mosquito-ITN interactions and how this impacts on the mosquito. METHODS A purpose-built benchtop apparatus with a closed 10 cm cubic chamber (the 'Baited-box') was used to video record behaviour of individual free-flying female Anopheles gambiae during approach and blood-feeding on a human hand through untreated nets and ITNs at close range. Time and duration of defined behavioural events, and knockdown and mortality at 1- and 24-h post-exposure respectively, were recorded for pyrethroid susceptible and resistant mosquitoes. RESULTS Using three human volunteers differing in relative attractiveness to mosquitoes, 328 mosquitoes were individually tested. There were no significant differences between response rates to ITNs and untreated nets (P > 0.1) or between resistant (Tiassalé) and susceptible (Kisumu) mosquito strains, at untreated nets (P = 0.39) or PermaNet 2.0 (P = 1). The sequence of behavioural events from host-seeking to completion of blood-feeding was consistent in all tests but duration and start time of events involving net contact were reduced or delayed respectively with ITNs. Blood-feeding durations at untreated nets (means from 4.25 to 8.47 min (95% confidence interval (CI) = 3.39-9.89) at 3 human volunteers) were reduced by 37-50% at PermaNet 2.0, in susceptible (mean 2.59-4.72 min, 95% CI = 1.54-5.5, P = < 0.05) and resistant (mean 4.20 min, 95% CI = 3.42-4.97, P = 0.01) strains. Total accumulated net contact was approximately 50% lower at PermaNet and Olyset ITNs (P < 0.0001) in susceptible (two of the three volunteers) and resistant mosquitoes. Times prior to first net contact were similar at untreated nets and ITNs (P > 0.2), and neither ITN type showed detectable spatial repellency. After initial contact, blood-feeding commenced later at Olyset (mean 2.76 min, 95% CI = 1.74-3.76, P = 0.0009) and PermaNet (mean 2.4 min, 95% CI = 1.52-3.33, P = 0.0058) than untreated netting (mean 0.68 min, 95% CI = 0.42-0.94). CONCLUSIONS The baited box offers a simple method for detailed characterization of mosquito behavioural responses to insecticidal nets, for comparing entomological modes of action between nets and for defining the behavioural responses of particular mosquito strains or populations. The device has potential as a screening assay in the search for novel net treatments and for investigations into behavioural resistance mechanisms.
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Affiliation(s)
- Angela Hughes
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Geraldine M Foster
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Amy Guy
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Agnes Matope
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Mayumi Abe
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - David Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Philip J McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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18
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Barrier bednets target malaria vectors and expand the range of usable insecticides. Nat Microbiol 2019; 5:40-47. [PMID: 31792426 DOI: 10.1038/s41564-019-0607-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 10/11/2019] [Indexed: 11/08/2022]
Abstract
Transmission of Plasmodium falciparum malaria parasites occurs when nocturnal Anopheles mosquito vectors feed on human blood. In Africa, where malaria burden is highest, bednets treated with pyrethroid insecticide were highly effective in preventing mosquito bites and reducing transmission, and essential to achieving unprecedented reductions in malaria until 2015 (ref. 1). Since then, progress has stalled2, and with insecticidal bednets losing efficacy against pyrethroid-resistant Anopheles vectors3,4, methods that restore performance are urgently needed to eliminate any risk of malaria returning to the levels seen before their widespread use throughout sub-Saharan Africa5. Here, we show that the primary malaria vector Anopheles gambiae is targeted and killed by small insecticidal net barriers positioned above a standard bednet in a spatial region of high mosquito activity but zero contact with sleepers, opening the way for deploying many more insecticides on bednets than is currently possible. Tested against wild pyrethroid-resistant A. gambiae in Burkina Faso, pyrethroid bednets with organophosphate barriers achieved significantly higher killing rates than bednets alone. Treated barriers on untreated bednets were equally effective, without significant loss of personal protection. Mathematical modelling of transmission dynamics predicted reductions in clinical malaria incidence with barrier bednets that matched those of 'next-generation' nets recommended by the World Health Organization against resistant vectors. Mathematical models of mosquito-barrier interactions identified alternative barrier designs to increase performance. Barrier bednets that overcome insecticide resistance are feasible using existing insecticides and production technology, and early implementation of affordable vector control tools is a realistic prospect.
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19
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Massue DJ, Lorenz LM, Moore JD, Ntabaliba WS, Ackerman S, Mboma ZM, Kisinza WN, Mbuba E, Mmbaga S, Bradley J, Overgaard HJ, Moore SJ. Comparing the new Ifakara Ambient Chamber Test with WHO cone and tunnel tests for bioefficacy and non-inferiority testing of insecticide-treated nets. Malar J 2019; 18:153. [PMID: 31039788 PMCID: PMC6492396 DOI: 10.1186/s12936-019-2741-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/21/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated net (ITN) durability, measured through physical integrity and bioefficacy, must be accurately assessed in order to plan the timely replacement of worn out nets and guide procurement of longer-lasting, cost-effective nets. World Health Organization (WHO) guidance advises that new intervention class ITNs be assessed 3 years after distribution, in experimental huts. In order to obtain information on whole-net efficacy cost-effectively and with adequate replication, a new bioassay, the Ifakara Ambient Chamber Test (I-ACT), a semi-field whole net assay baited with human host, was compared to established WHO durability testing methods. METHODS Two experiments were conducted using pyrethroid-susceptible female adult Anopheles gambiae sensu stricto comparing bioefficacy of Olyset®, PermaNet® 2.0 and NetProtect® evaluated by I-ACT and WHO cone and tunnel tests. In total, 432 nets (144/brand) were evaluated using I-ACT and cone test. Olyset® nets (132/144) that did not meet the WHO cone test threshold criteria (≥ 80% mortality or ≥ 95% knockdown) were evaluated using tunnel tests with threshold criteria of ≥ 80% mortality or ≥ 90% feeding inhibition for WHO tunnel and I-ACT. Pass rate of nets tested by WHO combined standard WHO bioassays (cone/tunnel tests) was compared to pass in I-ACT only by net brand and time after distribution. RESULTS Overall, more nets passed WHO threshold criteria when tested with I-ACT than with standard WHO bioassays 92% vs 69%, (OR: 4.1, 95% CI 3.5-4.7, p < 0.0001). The proportion of Olyset® nets that passed differed if WHO 2005 or WHO 2013 LN testing guidelines were followed: 77% vs 71%, respectively. Based on I-ACT results, PermaNet® 2.0 and NetProtect® demonstrated superior mortality and non-inferior feeding inhibition to Olyset® over 3 years of field use in Tanzania. CONCLUSION Ifakara Ambient Chamber Test may have use for durability studies and non-inferiority testing of new ITN products. It measures composite bioefficacy and physical integrity with both mortality and feeding inhibition endpoints, using fewer mosquitoes than standard WHO bioassays (cone and tunnel tests). The I-ACT is a high-throughput assay to evaluate ITN products that work through either contact toxicity or feeding inhibition. I-ACT allows mosquitoes to interact with a host sleeping underneath a net as encountered in the field, without risk to human participants.
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Affiliation(s)
- Dennis J Massue
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland.
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland.
- National Institute for Medical Research, Amani Research Centre, P. O. Box 81, Muheza, Tanga, Tanzania.
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania.
| | - Lena M Lorenz
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Jason D Moore
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | | | - Samuel Ackerman
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - Zawadi M Mboma
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - William N Kisinza
- National Institute for Medical Research, Amani Research Centre, P. O. Box 81, Muheza, Tanga, Tanzania
| | - Emmanuel Mbuba
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - Selemani Mmbaga
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Hans J Overgaard
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
| | - Sarah J Moore
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
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20
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Gaydecki P. Automated moth flight analysis in the vicinity of artificial light. BULLETIN OF ENTOMOLOGICAL RESEARCH 2019; 109:127-140. [PMID: 29745349 DOI: 10.1017/s0007485318000378] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Instrumentation and software for the automated analysis of insect flight trajectories is described, intended for quantifying the behavioural dynamics of moths in the vicinity of artificial light. For its time, this moth imaging system was relatively advanced and revealed hitherto undocumented insights into moth flight behaviour. The illumination source comprised a 125 W mercury vapour light, operating in the visible and near ultraviolet wavelengths, mounted on top of a mobile telescopic mast at heights of 5 and 7.1 m, depending upon the experiment. Moths were imaged in early September, at night and in field conditions, using a ground level video camera with associated optics including a heated steering mirror, wide angle lens and an electronic image intensifier. Moth flight coordinates were recorded at a rate of 50 images per second (fields) and transferred to a computer using a light pen (the only non-automated operation in the processing sequence). Software extracted ground speed vectors and, by instantaneous subtraction of wind speed data supplied by fast-response anemometers, the airspeed vectors. Accumulated density profiles of the track data revealed that moths spend most of their time at a radius of between 40 and 50 cm from the source, and rarely fly directly above it, from close range. Furthermore, the proportion of insects caught by the trap as a proportion of the number influenced by the light (and within the field of view of the camera) was very low; of 1600 individual tracks recorded over five nights, a total of only 12 were caught. Although trap efficiency is strongly dependent on trap height, time of night, season, moonlight and weather, the data analysis confirmed that moths do not exhibit straightforward positive phototaxis. In general, trajectory patterns become more complex with reduced distance from the illumination, with higher recorded values of speeds and angular velocities. However, these characteristics are further qualified by the direction of travel of the insect; the highest accelerations tended to occur when the insect was at close range, but moving away from the source. Rather than manifesting a simple positive phototaxis, the trajectories were suggestive of disorientation. Based on the data and the complex behavioural response, mathematical models were developed that described ideal density distribution in calm air and light wind speed conditions. The models did not offer a physiological hypothesis regarding the behavioural changes, but rather were tools for quantification and prediction. Since the time that the system was developed, instrumentation, computers and software have advanced considerably, allowing much more to be achieved at a small fraction of the original cost. Nevertheless, the analytical tools remain useful for automated trajectory analysis of airborne insects.
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Affiliation(s)
- P Gaydecki
- School of Electrical and Electronic Engineering, University of Manchester,Manchester M13 9PL,UK
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Affiliation(s)
- Janet Hemingway
- Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.
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Spitzen J, Takken W. Keeping track of mosquitoes: a review of tools to track, record and analyse mosquito flight. Parasit Vectors 2018; 11:123. [PMID: 29499744 PMCID: PMC5834890 DOI: 10.1186/s13071-018-2735-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/21/2018] [Indexed: 12/13/2022] Open
Abstract
The health impact of mosquito-borne diseases causes a huge burden on human societies. Recent vector control campaigns have resulted in promising declines in incidence and prevalence of these diseases, notably malaria, but resistance to insecticides and drugs are on the rise, threatening to overturn these gains. Moreover, several vector-borne diseases have re-emerged, requiring prompt and effective response measures. To improve and properly implement vector control interventions, the behaviour of the vectors must be well understood with detailed examination of mosquito flight being an essential component. Current knowledge on mosquito behaviour across its life history is briefly presented, followed by an overview of recent developments in automated tracking techniques for detailed interpretation of mosquito behaviour. These techniques allow highly accurate recording and observation of mating, feeding and oviposition behaviour. Software programmes built with specific algorithms enable quantification of these behaviours. For example, the crucial role of heat on host landing and the multimodal integration of carbon dioxide (CO2) with other host cues, has been unravelled based on three-dimensional tracking of mosquito flight behaviour. Furthermore, the behavioural processes underlying house entry and subsequent host searching and finding can be better understood by analysis of detailed flight recordings. Further potential of these technologies to solve knowledge gaps is discussed. The use of tracking techniques can support or replace existing monitoring tools and provide insights on mosquito behaviour that can lead to innovative and more effective vector-control measures.
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Affiliation(s)
- Jeroen Spitzen
- Laboratory of Entomology, Wageningen University and Research, PO Box 16, 6700 AA Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, PO Box 16, 6700 AA Wageningen, The Netherlands
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Sutcliffe J, Ji X, Yin S. How many holes is too many? A prototype tool for estimating mosquito entry risk into damaged bed nets. Malar J 2017; 16:304. [PMID: 28764726 PMCID: PMC5540337 DOI: 10.1186/s12936-017-1951-4] [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] [Received: 05/10/2017] [Accepted: 07/20/2017] [Indexed: 11/18/2022] Open
Abstract
Background Insecticide-treated bed nets (ITNs) have played an integral role in malaria reduction but how insecticide depletion and accumulating physical damage affect ITN performance is poorly understood. More accurate methods are needed to assess damage to bed nets so that they can be designed, deployed and replaced optimally. Methods Video recordings of female Anopheles gambiae in near approach (1–½ cm) to occupied untreated rectangular bed nets in a laboratory study were used to quantify the amount of mosquito activity (appearances over time) around different parts of the net, the per-appearance probability of a mosquito coming close to holes of different sizes (hole encounter) and the per-encounter probability of mosquitoes passing through holes of different sizes (hole passage). Results Appearance frequency on different parts of the net reflected previously reported patterns: the area of the net under greatest mosquito pressure was the roof, followed by the bottom 30 cm of the sides, followed by the 30 cm area immediately above this, followed by the upper two-thirds of the sides. The ratio of activity in these areas was (respectively) 250:33:5:1. Per-appearance probability of hole encounter on all parts of the net was strongly predicted by a factor combining hole perimeter and area. Per-encounter probability of hole passage, in turn, was strongly predicted by hole width. For a given width, there was a 20% greater risk of passage through holes on the roof than holes on the sides. Discussion Appearance, encounter and passage predictors correspond to various mosquito behaviours that have previously been described and are combined into a prototype mosquito entry risk tool that predicts mosquito entry rates for nets with various amounts of damage. Scenarios that use the entry risk tool to test the recommendations of the WHOPES proportionate hole index (pHI) suggest that the pHI hole size categories and failure to account for hole location likely sometimes lead to incorrect conclusions about net serviceability that could be avoided by using an entry risk tool of the form presented here instead. Practical methods of collecting hole position, shape and size information for bed net assessments using the tool in the field are discussed and include using image analysis and on-line geometric analysis tools. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1951-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- James Sutcliffe
- Department of Biology, Trent University, Peterborough, ON, Canada. .,Entomology Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - Xin Ji
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
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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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Parker JEA, Angarita Jaimes NC, Gleave K, Mashauri F, Abe M, Martine J, Towers CE, Towers D, McCall PJ. Host-seeking activity of a Tanzanian population of Anopheles arabiensis at an insecticide treated bed net. Malar J 2017; 16:270. [PMID: 28676092 PMCID: PMC5496219 DOI: 10.1186/s12936-017-1909-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/26/2017] [Indexed: 01/02/2023] Open
Abstract
Background Understanding how mosquitoes respond to long lasting insecticide treated nets (LLINs) is fundamental to sustaining the effectiveness of this essential control tool. We report on studies with a tracking system to investigate behaviour of wild anophelines at an LLIN, in an experimental hut at a rural site in Mwanza, Tanzania. Methods Groups of adult female mosquitoes (n = 10 per replicate) reared from larvae of a local population, identified as predominantly (95%) Anopheles arabiensis, were released in the hut. An infrared video tracking system recorded flight and net contact activity over 1 h as the mosquitoes attempted to reach a supine human volunteer within a bed net (either a deltamethrin-treated LLIN or an untreated control net). A range of activities, including flight path, position in relation to the bed net and duration of net contact, were quantified and compared between treatments. Results The total time that female An. arabiensis spent in flight around LLINs was significantly lower than at untreated nets [F(1,10) = 9.26, p = 0.012], primarily due to a substantial reduction in the time mosquitoes spent in persistent ‘bouncing’ flight [F(1,10) = 18.48, p = 0.002]. Most activity occurred at the net roof but significantly less so with LLINs (56.8% of total) than untreated nets [85.0%; Χ2 (15) = 234.69, p < 0.001]. Activity levels at the bed net directly above the host torso were significantly higher with untreated nets (74.2%) than LLINs [38.4%; Χ2 (15) = 33.54, p = 0.004]. ‘Visiting’ and ‘bouncing’ rates were highest above the volunteer’s chest in untreated nets (39.9 and 50.4%, respectively) and LLINs [29.9 and 42.4%; Χ2 (13) = 89.91, p < 0.001; Χ2 (9) = 45.73, p < 0.001]. Highest resting rates were above the torso in untreated nets [77%; Χ2 (9) = 63.12, p < 0.001], but in LLINs only 33.2% of resting occurred here [Χ2 (9) = 27.59, p = 0.001], with resting times spread between the short vertical side of the net adjacent to the volunteer’s head (21.8%) and feet (16.2%). Duration of net contact by a single mosquito was estimated at 204–290 s on untreated nets and 46–82 s on LLINs. While latency to net contact was similar in both treatments, the reduction in activity over 60 min was significantly more rapid for LLINs [F(1,10) = 6.81, p = 0.026], reiterating an ‘attract and kill’ rather than a repellent mode of action. Conclusions The study has demonstrated the potential for detailed investigations of behaviour of wild mosquito populations under field conditions. The results validate the findings of earlier laboratory studies on mosquito activity at LLINs, and reinforce the key role of multiple brief contacts at the net roof as the critical LLIN mode of action. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1909-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Josephine E A Parker
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | | | - Katherine Gleave
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Fabian Mashauri
- National Institute for Medical Research, Mwanza Medical Research Centre, PO Box 1462, Mwanza, Tanzania
| | - Mayumi Abe
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Jackline Martine
- National Institute for Medical Research, Mwanza Medical Research Centre, PO Box 1462, Mwanza, Tanzania
| | - Catherine E Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - David Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Philip J McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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Poh AH, Moghavvemi M, Leong CS, Lau YL, Safdari Ghandari A, Apau A, Mahamd Adikan FR. Collective behavior quantification on human odor effects against female Aedes aegypti mosquitoes-Open source development. PLoS One 2017; 12:e0171555. [PMID: 28152031 PMCID: PMC5289636 DOI: 10.1371/journal.pone.0171555] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 01/23/2017] [Indexed: 11/29/2022] Open
Abstract
Classifying and quantifying mosquito activity includes a plethora of categories, ranging from measuring flight speeds, repellency, feeding rates, and specific behaviors such as home entry, swooping and resting, among others. Entomologists have been progressing more toward using machine vision for efficiency for this endeavor. Digital methods have been used to study the behavior of insects in labs, for instance via three-dimensional tracking with specialized cameras to observe the reaction of mosquitoes towards human odor, heat and CO2, although virtually none was reported for several important fields, such as repellency studies which have a significant need for a proper response quantification. However, tracking mosquitoes individually is a challenge and only limited number of specimens can be studied. Although tracking large numbers of individual insects is hailed as one of the characteristics of an ideal automated image-based tracking system especially in 3D, it also is a costly method, often requiring specialized hardware and limited access to the algorithms used for mapping the specimens. The method proposed contributes towards (a) unlimited open source use, (b) a low-cost setup, (c) complete guide for any entomologist to adapt in terms of hardware and software, (d) simple to use, and (e) a lightweight data output for collective behavior analysis of mosquitoes. The setup is demonstrated by testing a simple response of mosquitoes in the presence of human odor versus control, one session with continuous human presence as a stimuli and the other with periodic presence. A group of female Aedes aegypti (Linnaeus) mosquitoes are released into a white-background chamber with a transparent acrylic panel on one side. The video feed of the mosquitoes are processed using filtered contours in a threshold-adjustable video. The mosquitoes in the chamber are mapped on the raster where the coordinates of each mosquito are recorded with the corresponding timestamp. The average distance of the blobs within the frames against time forms a spectra where behavioral patterns can be observed directly, whether any collective effect is observed. With this method, 3D tracking will not be required and a more straightforward data output can be obtained.
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Affiliation(s)
- Abdul Halim Poh
- Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
- Centre of Research in Applied Electronics, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Mahmoud Moghavvemi
- Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
- Centre of Research in Applied Electronics, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
- University of Science and Culture, Tehran, Iran
- * E-mail:
| | - Cherng Shii Leong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Alireza Safdari Ghandari
- Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
- Centre of Research in Applied Electronics, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Alexlee Apau
- Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
- Centre of Research in Applied Electronics, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Faisal Rafiq Mahamd Adikan
- Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
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Video reveals mosquito antics. Nature 2016. [DOI: 10.1038/532284a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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