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Charlwood JD. Swarming and mate selection in Anopheles gambiae mosquitoes (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:857-864. [PMID: 37392071 DOI: 10.1093/jme/tjad064] [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: 11/29/2022] [Revised: 03/10/2023] [Accepted: 06/14/2023] [Indexed: 07/02/2023]
Abstract
Treating both male and female Anopheles gambiae as if they are "boids" (a computer program that mimics flocking in birds) explains much of the swarming and mating behavior in this important group of malaria vectors. It is suggested that species specific swarm sites act as the mate recognition system in anophelines and it is proposed that virgin females respond to the swarm site per se rather than the swarm itself. Given the high operational sex ratio and the inability of any male to dominate all females within the swarm, it is considered that chance, rather than sexual selection, is the most important determinant of mating. The male being in the swarm may be a sufficiently strong signal to the female of his fitness, so that more elaborate sexual selection is unnecessary. The possibility of alternative mechanisms for mating may also exist but need to be investigated further. Given the importance of swarms as the isolating mechanism between species, emphasis should be placed on determining the characteristics of swarm sites and markers between them.
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Affiliation(s)
- Jacques Derek Charlwood
- Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Universidade Nova de Lisboa (UNL), Rua da Junqueira, 100, Lisbon 1349-008, Portugal
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Nkya TE, Fillinger U, Sangoro OP, Marubu R, Chanda E, Mutero CM. Six decades of malaria vector control in southern Africa: a review of the entomological evidence-base. Malar J 2022; 21:279. [PMID: 36184603 PMCID: PMC9526912 DOI: 10.1186/s12936-022-04292-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 09/05/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Countries in the southern Africa region have set targets for malaria elimination between 2020 and 2030. Malaria vector control is among the key strategies being implemented to achieve this goal. This paper critically reviews published entomological research over the past six decades in three frontline malaria elimination countries namely, Botswana Eswatini and Namibia, and three second-line malaria elimination countries including Mozambique, Zambia, and Zimbabwe. The objective of the review is to assess the current knowledge and highlight gaps that need further research attention to strengthen evidence-based decision-making toward malaria elimination. METHODS Publications were searched on the PubMed engine using search terms: "(malaria vector control OR vector control OR malaria vector*) AND (Botswana OR Swaziland OR Eswatini OR Zambia OR Zimbabwe OR Mozambique)". Opinions, perspectives, reports, commentaries, retrospective analysis on secondary data protocols, policy briefs, and reviews were excluded. RESULTS The search resulted in 718 publications with 145 eligible and included in this review for the six countries generated over six decades. The majority (139) were from three countries, namely Zambia (59) and Mozambique (48), and Zimbabwe (32) whilst scientific publications were relatively scanty from front-line malaria elimination countries, such as Namibia (2), Botswana (10) and Eswatini (4). Most of the research reported in the publications focused on vector bionomics generated mostly from Mozambique and Zambia, while information on insecticide resistance was mostly available from Mozambique. Extreme gaps were identified in reporting the impact of vector control interventions, both on vectors and disease outcomes. The literature is particularly scanty on important issues such as change of vector ecology over time and space, intervention costs, and uptake of control interventions as well as insecticide resistance. CONCLUSIONS The review reveals a dearth of information about malaria vectors and their control, most noticeable among the frontline elimination countries: Namibia, Eswatini and Botswana. It is of paramount importance that malaria vector research capacity and routine entomological monitoring and evaluation are strengthened to enhance decision-making, considering changing vector bionomics and insecticide resistance, among other determinants of malaria vector control.
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Affiliation(s)
- Theresia Estomih Nkya
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- University of Dar es Salaam, Mbeya College of Health and Allied Sciences, Mbeya, Tanzania
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | | | - Rose Marubu
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Emmanuel Chanda
- World Health Organization-Regional Office for Africa, Brazzaville, Republic of Congo
| | - Clifford Maina Mutero
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
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Adugna T, Getu E, Yewhelew D. Parous rate and longevity of anophelines mosquitoes in bure district, northwestern Ethiopia. PLoS One 2022; 17:e0263295. [PMID: 35120146 PMCID: PMC8815865 DOI: 10.1371/journal.pone.0263295] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 12/14/2021] [Indexed: 11/18/2022] Open
Abstract
The intensity of malaria transmission is measured by parous rate, daily survival rate, human blood meal frequency, sporozoite rate, and entomological inoculation rates. Female parous status is a key index of vector competence, adult vector longevity, recruitment rate of adult, and the length of a gonotrophic cycle. Hence, the present study was aimed to investigate the parous rate and the longevity of Anopheles mosquitoes in Bure District, Northwestern Ethiopia. Parous rate was estimated as the number of mosquitoes with parous ovaries divided by the number of females dissected multiplied by 100. Mosquito life expectancy (longevity as d) was estimated by. One way- ANOVA was applied to confirm the presence of parous rate difference in the villages (p < 0.05). A total of 952 unfed hosts-seeking Anopheles mosquitoes was dissected for parous rate determination. The overall parous rate of An. arabiensis in the district was 52.0%, and the highest parous rate was recorded in Shnebekuma than other villages (F 2, 33 = 6.974; p = 0.003). Similarly, the parous rate of An. cinereus showed significant variation among villages (F 2, 33 = 5.044, p = 0.012) and the highest rate (63.0%) was recorded in Bukta. The mean longevity of An. funestus, An. arabiensis, An. coustani, An. squamosus, An. pharoensis, and An. cinereus was 6.5 days, 4.6 days, 3.5 days, 3.7 days, 2.7 days, and 2.2 days, respectively. The longevity of each species was not sufficient to complete the life cycle of malaria parasite for malaria transmission throughout the year because P. falciparum requires from 12–14 day.
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Affiliation(s)
- Tilahun Adugna
- Department of Biology, Faculty of Natural and Computational Sciences, Debre Tabor, Amhara, Ethiopia
- * E-mail: ,
| | - Emana Getu
- Department of Zoological Science, Addis Ababa University, Addis Ababa, Addis Ababa, Ethiopia
| | - Delenasaw Yewhelew
- Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma, Oromia, Ethiopia
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Akuamoah-Boateng Y, Brenyah RC, Kwarteng SA, Obuam P, Owusu-Frimpong I, Agyapong AK, Badu K. Malaria Transmission, Vector Diversity, and Insecticide Resistance at a Peri-Urban Site in the Forest Zone of Ghana. FRONTIERS IN TROPICAL DISEASES 2021. [DOI: 10.3389/fitd.2021.739771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
IntroductionRecent surge of Anopheles resistance to major classes of World Health Organization (WHO)-approved insecticides globally necessitates the need for information about local malaria vector populations. It is believed that insecticide efficacy loss may lead to operational failure of control interventions and an increase in malaria infection transmission. We investigated the susceptibility levels of malaria vectors to all classes of WHO-approved vector control insecticides and described the dynamics of malaria transmission in a peri-urban setting.MethodsFit 3–5-day-old adults that emerged from Anopheles larvae collected from several different sites in the study area were subjected to the WHO bioassay for detecting insecticide resistance. The knockdown resistance gene (kdr) mutations within the vector populations were detected using PCR. Entomological inoculation rates were determined using the human landing catch technique and Plasmodium falciparum circumsporozoite ELISA.ResultsThe malaria vectors from the study area were resistant to all classes of insecticides tested. Out of the 284 Anopheles complex specimen assayed for the resistance study, 265 (93.30%) were identified as Anopheles gambiae s.s. The kdr gene was detected in 90% of the Anopheles gambiae s.s. assayed. In an area where Anopheles coluzzii resistance to insecticides had never been reported, the kdr gene was detected in 78% of the Anopheles coluzzii sampled. The entomological inoculation rate (EIR) for the dry season was 1.44 ib/m/n, whereas the EIR for the rainy season was 2.69 ib/m/n.ConclusionsThis study provides information on the high parasite inoculation rate and insecticide resistance of malaria vectors in a peri-urban community, which is critical in the development of an insecticide resistance management program for the community.
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Charlwood JD, Andegiorgish AK, Asfaha YE, Tekle Weldu L, Petros F, Legese L, Afewerki R, Mihreteab S, LeClair C, Kampango A. Novel sampling methods for monitoring Anopheles arabiensis from Eritrea. PeerJ 2021; 9:e11497. [PMID: 34322315 PMCID: PMC8297471 DOI: 10.7717/peerj.11497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 04/30/2021] [Indexed: 01/03/2023] Open
Abstract
Background Studies comparing novel collection methods for host seeking and resting mosquitoes A. arabiensis were undertaken in a village in Eritrea. Techniques included an odor baited trap, a novel tent-trap, human landing collection and three methods of resting collection. A technique for the collection of mosquitoes exiting vegetation is also described. Pre-gravid rates were determined by dissection of host seeking insects and post-prandial egg development among insects collected resting. Results Overall 5,382 host-seeking, 2,296 resting and 357 A. arabiensis exiting vegetation were collected. The Furvela tent-trap was the most efficient, risk-free method for the collection of outdoor host-seeking insects, whilst the Suna trap was the least effective method. Mechanical aspirators (the CDC backpack or the Prokopack aspirator) were superior to manual aspiration in a dark shelter but there was no advantage over manual aspiration in a well-lit one. An estimated two-thirds of newly-emerged mosquitoes went through a pre-gravid phase, feeding twice before producing eggs. Mosquitoes completed gonotrophic development in a dark shelter but left a well-lit shelter soon after feeding. One blood-fed female marked in the village was recaptured 2 days after release exiting vegetation close to the oviposition site and another, shortly after oviposition, attempting to feed on a human host 3 days after release. Exit rates of males from vegetation peaked 3 min after the initial male had left. Unfed and gravid females exited approximately 6 min after the first males. Conclusions Furvela tent-traps are suitable for the collection of outdoor biting A. arabiensis in Eritrea whilst the Prokopack sampler is the method of choice for the collection of resting insects. Constructing well-lit, rather than dark, animal shelters, may encourage otherwise endophilic mosquitoes to leave and so reduce their survival and hence their vectorial capacity.
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Affiliation(s)
- Jacques D Charlwood
- Epidemiology and Public Health, College of Health Sciences, Asmara, Eritrea.,Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Lisbon, Portugal
| | - Amanuel Kidane Andegiorgish
- Epidemiology and Public Health, College of Health Sciences, Asmara, Eritrea.,Department of Epidemiology and Biostatistics, Xi'an Jiaotong University, Shaanxi, China
| | | | - Liya Tekle Weldu
- Epidemiology and Public Health, College of Health Sciences, Asmara, Eritrea
| | - Feven Petros
- Epidemiology and Public Health, College of Health Sciences, Asmara, Eritrea
| | - Lidia Legese
- Epidemiology and Public Health, College of Health Sciences, Asmara, Eritrea
| | - Robel Afewerki
- Epidemiology and Public Health, College of Health Sciences, Asmara, Eritrea
| | | | | | - Ayubo Kampango
- Instituto Nacional de Saude, Maputo, Mozambique.,Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
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Abong'o B, Gimnig JE, Longman B, Odongo T, Wekesa C, Webwile A, Oloo B, Nduta M, Muchoki M, Omoke D, Wacira D, Opondo K, Ochomo E, Munga S, Donnelly MJ, Oxborough RM. Comparison of four outdoor mosquito trapping methods as potential replacements for human landing catches in western Kenya. Parasit Vectors 2021; 14:320. [PMID: 34118973 PMCID: PMC8196510 DOI: 10.1186/s13071-021-04794-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 05/20/2021] [Indexed: 11/23/2022] Open
Abstract
Introduction Longitudinal monitoring of outdoor-biting malaria vector populations is becoming increasingly important in understanding the dynamics of residual malaria transmission. However, the human landing catch (HLC), the gold standard for measuring human biting rates indoors and outdoors, is costly and raises ethical concerns related to increased risk of infectious bites among collectors. Consequently, routine data on outdoor-feeding mosquito populations are usually limited because of the lack of a scalable tool with similar sensitivity to outdoor HLC. Methodology The Anopheles trapping sensitivity of four baited proxy outdoor trapping methods—Furvela tent trap (FTT), host decoy trap (HDT), mosquito electrocuting traps (MET) and outdoor CDC light traps (OLT)—was assessed relative to HLC in a 5 × 5 replicated Latin square conducted over 25 nights in two villages of western Kenya. Indoor CDC light trap (ILT) was run in one house in each of the compounds with outdoor traps, while additional non-Latin square indoor and outdoor HLC collections were performed in one of the study villages. Results The MET, FTT, HDT and OLT sampled approximately 4.67, 7.58, 5.69 and 1.98 times more An. arabiensis compared to HLC, respectively, in Kakola Ombaka. Only FTT was more sensitive relative to HLC in sampling An. funestus in Kakola Ombaka (RR = 5.59, 95% CI 2.49–12.55, P < 0.001) and Masogo (RR = 4.38, 95% CI 1.62–11.80, P = 0.004) and in sampling An. arabiensis in Masogo (RR = 5.37, 95% CI 2.17–13.24, P < 0.001). OLT sampled significantly higher numbers of An. coustani in Kakola Ombaka (RR = 3.03, 95% CI 1.65–5.56, P < 0.001) and Masogo (RR = 2.88, 95% CI 1.15–7.22, P = 0.02) compared to HLC. OLT, HLC and MET sampled mostly An. coustani, FTT had similar proportions of An. funestus and An. arabiensis, while HDT sampled predominantly An. arabiensis in both villages. FTT showed close correlation with ILT in vector abundance for all three species at both collection sites. Conclusion FTT and OLT are simple, easily scalable traps and are potential replacements for HLC in outdoor sampling of Anopheles mosquitoes. However, the FTT closely mirrored indoor CDC light trap in mosquito indices and therefore may be more of an indoor mimic than a true outdoor collection tool. HDT and MET show potential for sampling outdoor host-seeking mosquitoes. However, the traps as currently designed may not be feasible for large-scale, longitudinal entomological monitoring. Therefore, the baited outdoor CDC light trap may be the most appropriate tool currently available for assessment of outdoor-biting and malaria transmission risk. Graphic abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04794-3.
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Affiliation(s)
- Bernard Abong'o
- Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya. .,PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya.
| | - John E Gimnig
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Bradley Longman
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Tobias Odongo
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Celestine Wekesa
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Amos Webwile
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Benjamin Oloo
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Mercy Nduta
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Margaret Muchoki
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Diana Omoke
- Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya
| | - Daniel Wacira
- The United States President's Malaria Initiative (PMI), US Embassy Nairobi, United Nations Avenue, Nairobi, Kenya
| | - Kevin Opondo
- PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya
| | - Stephen Munga
- Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya
| | - Martin J Donnelly
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Richard M Oxborough
- PMI VectorLink Project, Abt Associates Inc., 6130 Executive Blvd, Rockville, MD, 20852, USA
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Chabi J, Van’t Hof A, N’dri LK, Datsomor A, Okyere D, Njoroge H, Pipini D, Hadi MP, de Souza DK, Suzuki T, Dadzie SK, Jamet HP. Rapid high throughput SYBR green assay for identifying the malaria vectors Anopheles arabiensis, Anopheles coluzzii and Anopheles gambiae s.s. Giles. PLoS One 2019; 14:e0215669. [PMID: 31002694 PMCID: PMC6474623 DOI: 10.1371/journal.pone.0215669] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 04/05/2019] [Indexed: 12/04/2022] Open
Abstract
The Anopheles gambiae sensu lato species complex consists of a number of cryptic species with different habitats and behaviours. These morphologically indistinct species are identified by chromosome banding. Several molecular diagnostic techniques for distinguishing between An. coluzzii and An. gambiae are still under improvement. Although, the current SINE method for identification between An. coluzzii and An. gambiae works reliably, this study describes a refinement of the SINE method to increase sensitivity for identification of An. coluzzii, An. gambiae and An. arabiensis based on amplicon dissociation curve characteristics. Field-collected samples, laboratory-reared colonies and crossed specimens of the two species were used for the design of the protocol. An. gambiae, An. coluzzii, and hybrids of the two species were sampled from Ghana and An. arabiensis from Kenya. Samples were first characterised using conventional SINE PCR method, and further assayed using SYBR green, an intercalating fluorescent dye. The three species and hybrids were clearly differentiated using the melting temperature of the dissociation curves, with derivative peaks at 72°C for An. arabiensis, 75°C for An. gambiae and 86°C for An. coluzzii. The hybrids (An. gambiae / An. coluzzii) showed both peaks. This work is the first to describe a SYBR green real time PCR method for the characterization of An. arabiensis, An. gambiae and An. coluzzii and was purposely designed for basic melt-curve analysis (rather than high-resolution melt-curve) to allow it to be used on a wide range of real-time PCR machines.
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Affiliation(s)
- Joseph Chabi
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Arjen Van’t Hof
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Louis K. N’dri
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Alex Datsomor
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Dora Okyere
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Harun Njoroge
- Kemri-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Dimitra Pipini
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Melinda P. Hadi
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
- Vestergaard Frandsen East Africa, Nairobi, Kenya
| | - Dziedzom K. de Souza
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Takashi Suzuki
- Section Environmental Parasitology, Kobe-Tokiwa University, Nagata-Ku, Japan
| | - Samuel K. Dadzie
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Helen P. Jamet
- Vestergaard regional office, Washington DC, United States of America
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Charlwood JD, Tomás EVE, Andegiorgish AK, Mihreteab S, LeClair C. 'We like it wet': a comparison between dissection techniques for the assessment of parity in Anopheles arabiensis and determination of sac stage in mosquitoes alive or dead on collection. PeerJ 2018; 6:e5155. [PMID: 30018854 PMCID: PMC6044268 DOI: 10.7717/peerj.5155] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 06/11/2018] [Indexed: 11/28/2022] Open
Abstract
Background The determination of parous rates in mosquitoes, despite numerous shortcomings, remains a tool to evaluate the effectiveness of control programs and to determine vectorial capacity in malaria vectors. Two dissection techniques are used for this. For one, the tracheoles of dried ovaries are examined with a compound microscope and in the other the follicular stalk of ovaries is examined, wet, with a stereomicroscope. The second method also enables the sac stage of parous insects (which provides information on the duration of the oviposition cycle) and the mated status of insects to be determined. Despite widespread use the two techniques have not previously been compared. Methods We compared the two dissection techniques using Anopheles arabiensis, collected with a tent-trap in Eritrea. The paired ovaries were removed in water and one was examined by each method. From a separate set of dissections from Tanzania, we also determined if the sac stages of Anopheles gambiae s.l. (83% of 183 identified by PCR being Anopheles arabiensis the remainder being A. gambiae) that were alive on collection were different to those that died on collection and what the implications for vectorial capacity estimation might be. Results Seven per cent of the dry ovaries could not be classified due to granulation (yolk) in the ovariole that obscured the tracheoles. The sensitivity of the dry dissection was 88.51% (CI [79.88–94.35%]) and the specificity was 93.55% (CI [87.68–97.17%]) among the 211 ovaries that could be classified by the dry technique and compared to the ovaries dissected wet. 1,823 live and 1,416 dead from Furvela tent-traps, CDC light-trap and window-trap collections were dissected ‘wet’ from Tanzania. In these collections parous insects were more likely to die compared to nulliparous ones. The proportion of parous mosquitoes with ‘a’ sacs (indicative of recent oviposition) was significantly greater in insects that were dead (0.36) on collection in the morning compared to those that were alive (0.12) (Chi square 138.93, p < 0.001). There was a preponderance of newly emerged virgin insects in the outdoor collection (Chi sq = 8.84, p = 0.003). Conclusions In anophelines the examination of mosquito ovaries using transmitted light in a ‘wet’ dissection is a more useful and informative technique than examination of dry ovaries. In order to correctly estimate the duration of the oviposition cycle mosquitoes should be dissected as soon as possible after collection. Younger insects were more likely to attempt to feed outdoors rather than indoors.
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Affiliation(s)
- Jacques D Charlwood
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisbon, Portugal
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Charlwood JD, Rowland M, Protopopoff N, Le Clair C. The Furvela tent-trap Mk 1.1 for the collection of outdoor biting mosquitoes. PeerJ 2017; 5:e3848. [PMID: 29158961 PMCID: PMC5694212 DOI: 10.7717/peerj.3848] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 09/04/2017] [Indexed: 11/20/2022] Open
Abstract
Outdoor transmission of malaria and other vector borne diseases remains a problem. The WHO has recently recognized the need for suitable methods for assessing vector density outdoors and a number of tent-traps have been developed. Only one such trap, the Furvela tent-trap, does not require an 'entry' behavior on the part of the mosquito. It remains the cheapest and lightest tent-trap described. It takes less than two minutes to install and is the only trap that uses readily available components. Here we describe recent modifications to the trap, which make it even easier to set up in the field, provide a standard operating procedure (SOP) and describe some recent experiments examining the effect of the addition of light and door placement to working of the trap. The trap provides the closest approximation to CDC light-traps, widely used to collect indoor biting mosquitoes. This enables the effect of both indoor and outdoor interventions on mosquito density and behavior to be determined.
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Affiliation(s)
- Jacques D. Charlwood
- Department of Disease Control, London School of Hygiene & Tropical Medicine, University of London, London, United Kingdom
- Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Rua da Junqueira, Global Health and Tropical Medicine, GHTM, Lisbon, Portugal
- Pan African Malaria Vector Research Consortium (PAMVERC), Muleba, Tanzania
| | - Mark Rowland
- Department of Disease Control, London School of Hygiene & Tropical Medicine, University of London, London, United Kingdom
- Pan African Malaria Vector Research Consortium (PAMVERC), Muleba, Tanzania
| | - Natacha Protopopoff
- Department of Disease Control, London School of Hygiene & Tropical Medicine, University of London, London, United Kingdom
- Pan African Malaria Vector Research Consortium (PAMVERC), Muleba, Tanzania
| | - Corey Le Clair
- Department of Disease Control, London School of Hygiene & Tropical Medicine, University of London, London, United Kingdom
- Pan African Malaria Vector Research Consortium (PAMVERC), Muleba, Tanzania
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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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Chabi J, Baidoo PK, Datsomor AK, Okyere D, Ablorde A, Iddrisu A, Wilson MD, Dadzie SK, Jamet HP, Diclaro JW. Insecticide susceptibility of natural populations of Anopheles coluzzii and Anopheles gambiae (sensu stricto) from Okyereko irrigation site, Ghana, West Africa. Parasit Vectors 2016; 9:182. [PMID: 27030033 PMCID: PMC4815066 DOI: 10.1186/s13071-016-1462-0] [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: 11/30/2015] [Accepted: 03/17/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The increasing spread of insecticide resistance in malaria vectors has been well documented across sub-Saharan Africa countries. The influence of irrigation on increasing vector resistance is poorly understood, and is critical to successful and ethical implementation of food security policies. This study investigated the insecticide resistance status of An. gambiae (s.l.) mosquitoes collected from the irrigated rice area of Okyereko, a village containing about 42 hectares of irrigated field within an irrigation project plan in the Central Region of Ghana. Large amounts of insecticides, herbicides and fertilizers are commonly used in the area to boost the annual production of the rice. METHODS Mosquito larvae were collected and adults were assayed from the F1 progeny. The resistance status, allele and genotype were characterized using WHO susceptibility testing and PCR methods respectively. RESULTS The An. gambiae (s.l.) populations from Okyereko are highly resistant to DDT and pyrethroid insecticides, with possible involvement of metabolic mechanisms including the elevation of P450 and GST enzyme as well as P-gp activity. The population was mostly composed of An. coluzzii specimens (more than 96 %) with kdr and ace-1 frequencies of 0.9 and 0.2 %, respectively. CONCLUSION This study brings additional information on insecticide resistance and the characterization of An. gambiae (s.l.) mosquitoes from Okyereko, which can be helpful in decision making for vector control programmes in the region.
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Affiliation(s)
- Joseph Chabi
- Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana. .,Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.
| | - Philip K Baidoo
- Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Alex K Datsomor
- Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.,Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Dora Okyere
- Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.,Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Aikins Ablorde
- Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.,Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Alidu Iddrisu
- Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.,Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Michael D Wilson
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Samuel K Dadzie
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | | | - Joseph W Diclaro
- Vector Biology Research Program, U.S. Naval Medical Research Unit No 3, Cairo, Egypt
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12
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Lees RS, Knols B, Bellini R, Benedict MQ, Bheecarry A, Bossin HC, Chadee DD, Charlwood J, Dabiré RK, Djogbenou L, Egyir-Yawson A, Gato R, Gouagna LC, Hassan MM, Khan SA, Koekemoer LL, Lemperiere G, Manoukis NC, Mozuraitis R, Pitts RJ, Simard F, Gilles JR. Review: Improving our knowledge of male mosquito biology in relation to genetic control programmes. Acta Trop 2014; 132 Suppl:S2-11. [PMID: 24252487 DOI: 10.1016/j.actatropica.2013.11.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 11/09/2013] [Indexed: 12/26/2022]
Abstract
The enormous burden placed on populations worldwide by mosquito-borne diseases, most notably malaria and dengue, is currently being tackled by the use of insecticides sprayed in residences or applied to bednets, and in the case of dengue vectors through reduction of larval breeding sites or larviciding with insecticides thereof. However, these methods are under threat from, amongst other issues, the development of insecticide resistance and the practical difficulty of maintaining long-term community-wide efforts. The sterile insect technique (SIT), whose success hinges on having a good understanding of the biology and behaviour of the male mosquito, is an additional weapon in the limited arsenal against mosquito vectors. The successful production and release of sterile males, which is the mechanism of population suppression by SIT, relies on the release of mass-reared sterile males able to confer sterility in the target population by mating with wild females. A five year Joint FAO/IAEA Coordinated Research Project brought together researchers from around the world to investigate the pre-mating conditions of male mosquitoes (physiology and behaviour, resource acquisition and allocation, and dispersal), the mosquito mating systems and the contribution of molecular or chemical approaches to the understanding of male mosquito mating behaviour. A summary of the existing knowledge and the main novel findings of this group is reviewed here, and further presented in the reviews and research articles that form this Acta Tropica special issue.
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Charlwood JD, Braganca M. The effect of rainstorms on adult Anopheles funestus behavior and survival. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2012; 37:252-256. [PMID: 22548561 DOI: 10.1111/j.1948-7134.2012.00224.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We describe the effect that the passage of a cold front, with a subsequent heavy rainstorm ten days later, had on a population of Anopheles funestus mosquitoes collected exiting houses or in light-traps from a village in southern Mozambique. Temperature effects explained 40% (r=0.634; p <0.001) of the variation in numbers of males collected and 19% of the variation in gravid females collected (r=0.437; p=0.033). The age structure of mosquitoes varied according to distance from the breeding site (χ(2) = 64.1, df 6, p <0.001). The proportion of parous insects that were caught in the light-traps with sacs (χ(2) = 6.33, d.f. 2, p=0.042) and young insects that had mated before being collected (χ(2) = 13,3, d.f. 2, p=0.001) were reduced on the night of the rain but this effect was short lived. It is concluded that the effect of rain on mosquito populations depends on the kind of water body used for larval development.
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Affiliation(s)
- J Derek Charlwood
- DBL - Entomology, 57 Thorvaldensvej Fredriksberg, Fredriksberg 1871, Denmark.
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