1
|
Mwima R, Hui TYJ, Nanteza A, Burt A, Kayondo JK. Potential persistence mechanisms of the major Anopheles gambiae species complex malaria vectors in sub-Saharan Africa: a narrative review. Malar J 2023; 22:336. [PMID: 37936194 PMCID: PMC10631165 DOI: 10.1186/s12936-023-04775-0] [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: 03/22/2023] [Accepted: 10/30/2023] [Indexed: 11/09/2023] Open
Abstract
The source of malaria vector populations that re-establish at the beginning of the rainy season is still unclear yet knowledge of mosquito behaviour is required to effectively institute control measures. Alternative hypotheses like aestivation, local refugia, migration between neighbouring sites, and long-distance migration (LDM) are stipulated to support mosquito persistence. This work assessed the malaria vector persistence dynamics and examined various studies done on vector survival via these hypotheses; aestivation, local refugia, local or long-distance migration across sub-Saharan Africa, explored a range of methods used, ecological parameters and highlighted the knowledge trends and gaps. The results about a particular persistence mechanism that supports the re-establishment of Anopheles gambiae, Anopheles coluzzii or Anopheles arabiensis in sub-Saharan Africa were not conclusive given that each method used had its limitations. For example, the Mark-Release-Recapture (MRR) method whose challenge is a low recapture rate that affects its accuracy, and the use of time series analysis through field collections whose challenge is the uncertainty about whether not finding mosquitoes during the dry season is a weakness of the conventional sampling methods used or because of hidden shelters. This, therefore, calls for further investigations emphasizing the use of ecological experiments under controlled conditions in the laboratory or semi-field, and genetic approaches, as they are known to complement each other. This review, therefore, unveils and assesses the uncertainties that influence the different malaria vector persistence mechanisms and provides recommendations for future studies.
Collapse
Affiliation(s)
- Rita Mwima
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity (COVAB), Makerere University, Kampala, Uganda
| | - Tin-Yu J Hui
- Silwood Park Campus, Department of Life Sciences, Imperial College London, Ascot, UK
| | - Ann Nanteza
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity (COVAB), Makerere University, Kampala, Uganda
| | - Austin Burt
- Silwood Park Campus, Department of Life Sciences, Imperial College London, Ascot, UK
| | - Jonathan K Kayondo
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda.
| |
Collapse
|
2
|
Barr JS, Estevez-Lao TY, Khalif M, Saksena S, Yarlagadda S, Farah O, Shivere Y, Hillyer JF. Temperature and age, individually and interactively, shape the size, weight, and body composition of adult female mosquitoes. JOURNAL OF INSECT PHYSIOLOGY 2023; 148:104525. [PMID: 37236342 DOI: 10.1016/j.jinsphys.2023.104525] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 05/28/2023]
Abstract
Most insects are poikilotherms and ectotherms, so their body temperature fluctuates and closely aligns with the temperature of their environment. The rise in global temperatures is affecting the physiology of insects by altering their ability to survive, reproduce, and transmit disease. Aging also impacts insect physiology because the body deteriorates via senescence as the insect ages. Although temperature and age both impact insect biology, these factors have historically been studied in isolation. So, it is unknown whether or how temperature and age interact to shape insect physiology. Here, we investigated the effects of warmer temperature (27 °C, 30 °C and 32 °C), aging (1, 5, 10, and 15 days post-eclosion), and their interaction on the size and body composition of the mosquito, Anopheles gambiae. We found that warmer temperatures result in slightly smaller adult mosquitoes, as measured by abdomen and tibia length. Aging alters both abdominal length and dry weight in a manner that correlates with the increase in energetic resources and tissue remodeling that occurs after metamorphosis and the senescence-based decline that ensues later. Moreover, the carbohydrate and lipid contents of adult mosquitoes are not meaningfully affected by temperature but are altered by aging: carbohydrate content increases with age whereas lipid content increases over the first few days of adulthood and then decreases. Protein content decreases with both rising temperature and aging, and the aging-associated decrease accelerates at warmer temperatures. Altogether, temperature and age, individually and to a lesser extent interactively, shape the size and composition of adult mosquitoes.
Collapse
Affiliation(s)
- Jordyn S Barr
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Tania Y Estevez-Lao
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Marina Khalif
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Saksham Saksena
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Sagnik Yarlagadda
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Ommay Farah
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Yasmine Shivere
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Julián F Hillyer
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
| |
Collapse
|
3
|
Duval P, Antonelli P, Aschan-Leygonie C, Valiente Moro C. Impact of Human Activities on Disease-Spreading Mosquitoes in Urban Areas. J Urban Health 2023; 100:591-611. [PMID: 37277669 PMCID: PMC10322816 DOI: 10.1007/s11524-023-00732-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/25/2023] [Indexed: 06/07/2023]
Abstract
Urbanization is one of the leading global trends of the twenty-first century that has a significant impact on health. Among health challenges caused by urbanization, the relationship of urbanization between emergence and the spread of mosquito-borne infectious diseases (MBIDs) is a great public health concern. Urbanization processes encompass social, economic, and environmental changes that directly impact the biology of mosquito species. In particular, urbanized areas experience higher temperatures and pollution levels than outlying areas but also favor the development of infrastructures and objects that are favorable to mosquito development. All these modifications may influence mosquito life history traits and their ability to transmit diseases. This review aimed to summarize the impact of urbanization on mosquito spreading in urban areas and the risk associated with the emergence of MBIDs. Moreover, mosquitoes are considered as holobionts, as evidenced by numerous studies highlighting the role of mosquito-microbiota interactions in mosquito biology. Taking into account this new paradigm, this review also represents an initial synthesis on how human-driven transformations impact microbial communities in larval habitats and further interfere with mosquito behavior and life cycle in urban areas.
Collapse
Affiliation(s)
- Pénélope Duval
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, Bât. André Lwoff, 10 rue Raphaël Dubois, F-69622, Villeurbanne, France
| | - Pierre Antonelli
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, Bât. André Lwoff, 10 rue Raphaël Dubois, F-69622, Villeurbanne, France
| | - Christina Aschan-Leygonie
- University of Lyon, Université Lumière Lyon 2, UMR 5600 CNRS Environnement Ville Société, F-69007, Lyon, France
| | - Claire Valiente Moro
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, Bât. André Lwoff, 10 rue Raphaël Dubois, F-69622, Villeurbanne, France.
| |
Collapse
|
4
|
Faiman R, Yaro AS, Dao A, Sanogo ZL, Diallo M, Samake D, Yossi O, Veru LM, Graber LC, Conte AR, Kouam C, Krajacich BJ, Lehmann T. Isotopic evidence that aestivation allows malaria mosquitoes to persist through the dry season in the Sahel. Nat Ecol Evol 2022; 6:1687-1699. [PMID: 36216903 DOI: 10.1038/s41559-022-01886-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 08/11/2022] [Indexed: 11/09/2022]
Abstract
Data suggest that the malaria vector mosquito Anopheles coluzzii persists during the dry season in the Sahel through a dormancy mechanism known as aestivation; however, the contribution of aestivation compared with alternative strategies such as migration is unknown. Here we marked larval Anopheles mosquitoes in two Sahelian villages in Mali using deuterium (2H) to assess the contribution of aestivation to persistence of mosquitoes through the seven-month dry season. After an initial enrichment period, 33% of An. coluzzii mosquitoes were strongly marked. Seven months following enrichment, multiple analysis methods supported the ongoing presence of marked mosquitoes, compatible with the prediction that the fraction of marked mosquitoes should remain stable throughout the dry season if local aestivation is occurring. The results suggest that aestivation is a major persistence mechanism of An. coluzzii in the Sahel, contributing at least 20% of the adults at the onset of rains. This persistence strategy could influence mosquito control and malaria elimination campaigns.
Collapse
Affiliation(s)
- Roy Faiman
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA.
| | - Alpha S Yaro
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Adama Dao
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Zana L Sanogo
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Djibril Samake
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Ousmane Yossi
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Laura M Veru
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Leland C Graber
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Abigail R Conte
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Cedric Kouam
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | | | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| |
Collapse
|
5
|
Yaro AS, Linton YM, Dao A, Diallo M, Sanogo ZL, Samake D, Ousmane Y, Kouam C, Krajacich BJ, Faiman R, Bamou R, Woo J, Chapman JW, Reynolds DR, Lehmann T. Diversity, composition, altitude, and seasonality of high-altitude windborne migrating mosquitoes in the Sahel: Implications for disease transmission. FRONTIERS IN EPIDEMIOLOGY 2022; 2:1001782. [PMID: 38455321 PMCID: PMC10910920 DOI: 10.3389/fepid.2022.1001782] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 09/16/2022] [Indexed: 03/09/2024]
Abstract
Recent studies have reported Anopheles mosquitoes captured at high-altitude (40-290 m above ground) in the Sahel. Here, we describe this migration modality across genera and species of African Culicidae and examine its implications for disease transmission and control. As well as Anopheles, six other genera-Culex, Aedes, Mansonia, Mimomyia, Lutzia, and Eretmapodites comprised 90% of the 2,340 mosquitoes captured at altitude. Of the 50 molecularly confirmed species (N = 2,107), 33 species represented by multiple specimens were conservatively considered high-altitude windborne migrants, suggesting it is a common migration modality in mosquitoes (31-47% of the known species in Mali), and especially in Culex (45-59%). Overall species abundance varied between 2 and 710 specimens/species (in Ae. vittatus and Cx. perexiguus, respectively). At altitude, females outnumbered males 6:1, and 93% of the females have taken at least one blood meal on a vertebrate host prior to their departure. Most taxa were more common at higher sampling altitudes, indicating that total abundance and diversity are underestimated. High-altitude flight activity was concentrated between June and November coinciding with availability of surface waters and peak disease transmission by mosquitoes. These hallmarks of windborne mosquito migration bolster their role as carriers of mosquito-borne pathogens (MBPs). Screening 921 mosquitoes using pan-Plasmodium assays revealed that thoracic infection rate in these high-altitude migrants was 2.4%, providing a proof of concept that vertebrate pathogens are transported by windborne mosquitoes at altitude. Fourteen of the 33 windborne mosquito species had been reported as vectors to 25 MBPs in West Africa, which represent 32% of the MBPs known in that region and include those that inflict the heaviest burden on human and animal health, such as malaria, yellow fever, dengue, and Rift Valley fever. We highlight five arboviruses that are most likely affected by windborne mosquitoes in West Africa: Rift Valley fever, O'nyong'nyong, Ngari, Pangola, and Ndumu. We conclude that the study of windborne spread of diseases by migrating insects and the development of surveillance to map the sources, routes, and destinations of vectors and pathogens is key to understand, predict, and mitigate existing and new threats of public health.
Collapse
Affiliation(s)
- Alpha Seydou Yaro
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Yvonne-Marie Linton
- Walter Reed Biosystematics Unit, Smithsonian Institution Museum Support Center, Suitland, MD, United States
- Department of Entomology, Smithsonian Institution, National Museum of Natural History, Washington, DC, United States
- One Health Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Adama Dao
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Zana L. Sanogo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Djibril Samake
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Yossi Ousmane
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Cedric Kouam
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
| | | | - Roy Faiman
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
| | - Roland Bamou
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
| | - Joshua Woo
- Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Jason W. Chapman
- Centre for Ecology and Conservation, and Environment and Sustainability Institute, University of Exeter, Penryn, United Kingdom
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Don R. Reynolds
- Natural Resources Institute, University of Greenwich, Chatham, United Kingdom
- Rothamsted Research, Harpenden, United Kingdom
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
| |
Collapse
|
6
|
Munisi DZ, Mathania MM. Adult Anopheles Mosquito Distribution at a Low and High Malaria Transmission Site in Tanzania. BIOMED RESEARCH INTERNATIONAL 2022; 2022:6098536. [PMID: 35047638 PMCID: PMC8763487 DOI: 10.1155/2022/6098536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Accepted: 12/11/2021] [Indexed: 11/20/2022]
Abstract
Malaria parasites are only transmitted by female mosquitoes of the genus Anopheles; hence, the disease's distribution is linked to that of the vector mosquitoes. As such, the goal of this study was to find out the spatial and temporal distribution of Anopheles mosquito adults in the research sites. This was a repeated cross-sectional ecological study that took place in Morogoro and Dodoma, Tanzania. Vacuum aspiration was used to collect mosquitoes both outside and inside human dwellings. All mosquito-related data was collected and entered into appropriate data collection forms. Female mosquitoes were recognized morphologically using Gillies and Coetzee morphological criteria, followed by PCR. In total, about 2742 Anopheles mosquitoes with an average collection of 18.21 ± 1.12 per day were collected outside human houses of which 1717 (10.51 ± 1.17) and 1025 (8.42 ± 1.41) were collected from Morogoro and Dodoma, respectively. Of the captured mosquitoes, 89.0%, 10.0%, and 1.0% were recognized as Anopheles arabiensis, Anopheles gambiae s.s., and Anopheles quadrianulatus, respectively. The distribution varied significantly with seasons, whereby 302 (4.72 ± 1.04) and 2440 (12.96 ± 1.52) mosquitoes were captured in the cold-dry and warm-wet season, respectively (p < 0.0001). Of the captured mosquitoes, 42.33%, 16.33%, 14.96%, and 4.27 were found on the ceiling, stored junks, verandas, and barks/tree, respectively. In malaria-endemic countries, vector control forms an important component of the malaria control efforts. This study found significant variation of Anopheles mosquito abundance in time and space with Anopheles arabiensis being the most predominant malaria vector. This signifies the need to introduce mosquito control methods that will target the less anthropophilic Anopheles arabiensis or the immature aquatic stages. The study further found that underbeds, store room/piled bags, and undisturbed curtains were the most preferred resting places by mosquitoes signifying to be the most effective strategic sites for spraying insecticides during the implementation of indoor residual spraying (IRS).
Collapse
Affiliation(s)
- David Zadock Munisi
- Department of Microbiology and Parasitology, School of Medicine and Dentistry, The University of Dodoma, P.O. Box 259, Dodoma, Tanzania
| | - Mary Mathew Mathania
- Department of Basic and Behavioral Sciences, School of Nursing, Saint John's University of Tanzania, Dodoma, Tanzania
| |
Collapse
|
7
|
Diversity, dynamics, direction, and magnitude of high-altitude migrating insects in the Sahel. Sci Rep 2020; 10:20523. [PMID: 33239619 PMCID: PMC7688652 DOI: 10.1038/s41598-020-77196-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 10/28/2020] [Indexed: 11/08/2022] Open
Abstract
Long-distance migration of insects impacts food security, public health, and conservation–issues that are especially significant in Africa. Windborne migration is a key strategy enabling exploitation of ephemeral havens such as the Sahel, however, its knowledge remains sparse. In this first cross-season investigation (3 years) of the aerial fauna over Africa, we sampled insects flying 40–290 m above ground in Mali, using nets mounted on tethered helium-filled balloons. Nearly half a million insects were caught, representing at least 100 families from thirteen orders. Control nets confirmed that the insects were captured at altitude. Thirteen ecologically and phylogenetically diverse species were studied in detail. Migration of all species peaked during the wet season every year across localities, suggesting regular migrations. Species differed in flight altitude, seasonality, and associated weather conditions. All taxa exhibited frequent flights on southerly winds, accounting for the recolonization of the Sahel from southern source populations. “Return” southward movement occurred in most taxa. Estimates of the seasonal number of migrants per species crossing Mali at latitude 14°N were in the trillions, and the nightly distances traversed reached hundreds of kilometers. The magnitude and diversity of windborne insect migration highlight its importance and impacts on Sahelian and neighboring ecosystems.
Collapse
|
8
|
Krajacich BJ, Sullivan M, Faiman R, Veru L, Graber L, Lehmann T. Induction of long-lived potential aestivation states in laboratory An. gambiae mosquitoes. Parasit Vectors 2020; 13:412. [PMID: 32787948 PMCID: PMC7424682 DOI: 10.1186/s13071-020-04276-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 08/03/2020] [Indexed: 12/16/2022] Open
Abstract
Background How anopheline mosquitoes persist through the long dry season in Africa remains a gap in our understanding of these malaria vectors. To span this period in locations such as the Sahelian zone of Mali, mosquitoes must either migrate to areas of permanent water, recolonize areas as they again become favorable, or survive in harsh conditions including high temperatures, low humidity, and an absence of surface water (required for breeding). Adult mosquitoes surviving through this season must dramatically extend their typical lifespan (averaging 2–3 weeks) to 7 months. Previous work has found evidence that the malaria mosquito An. coluzzii, survives over 200 days in the wild between rainy seasons in a presumed state of aestivation (hibernation), but this state has so far not been replicated in laboratory conditions. The inability to recapitulate aestivation in the lab hinders addressing key questions such as how this state is induced, how it affects malaria vector competence, and its impact on disease transmission. Methods In effort to induce aestivation, we held laboratory mosquitoes in climate-controlled incubators with a range of conditions that adjusted humidity (40–85% RH), temperature (18–27 °C), and light conditions (8–12 h of light) and evaluated their survivorship. These conditions were chosen to mimic the late rainy and dry seasons as well as relevant extremes these mosquitoes may experience during aestivation. Results We found that by priming mosquitoes in conditions simulating the late wet season in Mali, and maintaining mosquitoes in reduced light/temperature, mean mosquito survival increased from 18.34 ± 0.65 to 48.02 ± 2.87 days, median survival increased from 19 (95% CI 17–21) to 50 days (95% CI 40–58), and the maximum longevity increased from 38 to 109 days (P-adj < 0.001). While this increase falls short of the 200 + day survival seen in field mosquitoes, this extension is substantially higher than previously found through environmental or dietary modulation and is hard to reconcile with states other than aestivation. This finding will provide a platform for future characterization of this state, and allow for comparison to field collected samples. ![]()
Collapse
Affiliation(s)
- Benjamin J Krajacich
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA.
| | - Margery Sullivan
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Roy Faiman
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Laura Veru
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Leland Graber
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA.
| |
Collapse
|
9
|
Faiman R, Yaro AS, Diallo M, Dao A, Djibril S, Sanogo ZL, Sullivan M, Krishna A, Krajacich BJ, Lehmann T. Quantifying flight aptitude variation in wild Anopheles gambiae in order to identify long-distance migrants. Malar J 2020; 19:263. [PMID: 32698842 PMCID: PMC7374819 DOI: 10.1186/s12936-020-03333-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 07/10/2020] [Indexed: 11/16/2022] Open
Abstract
Background In the West African Sahel, mosquito reproduction is halted during the 5–7 month-long dry season, due to the absence of surface waters required for larval development. However, recent studies have suggested that both Anopheles gambiae sensu stricto (s.s.) and Anopheles arabiensis repopulate this region via migration from distant locations where larval sites are perennial. Anopheles coluzzii engages in more regional migration, presumably within the Sahel, following shifting resources correlating with the ever-changing patterns of Sahelian rainfall. Understanding mosquito migration is key to controlling malaria—a disease that continues to claim more than 400,000 lives annually, especially those of African children. Using tethered flight data of wild mosquitoes, the distribution of flight parameters were evaluated as indicators of long-range migrants versus appetitive flyers, and the species specific seasonal differences and gonotrophic states compared between two flight activity modalities. Morphometrical differences were evaluated in the wings of mosquitoes exhibiting high flight activity (HFA) vs. low flight activity (LFA). Methods A novel tethered-flight assay was used to characterize flight in the three primary malaria vectors- An. arabiensis, An. coluzzii and An. gambiae s.s. The flights of tethered wild mosquitoes were audio-recorded from 21:00 h to 05:00 h in the following morning and three flight aptitude indices were examined: total flight duration, longest flight bout, and the number of flight bouts during the assay. Results The distributions of all flight indices were strongly skewed to the right, indicating that the population consisted of a majority of low-flight activity (LFA) mosquitoes and a minority of high-flight activity (HFA) mosquitoes. The median total flight was 586 s and the maximum value was 16,110 s (~ 4.5 h). In accordance with recent results, flight aptitude peaked in the wet season, and was higher in gravid females than in non-blood-fed females. Flight aptitude was also found to be higher in An. coluzzii compared to An. arabiensis, with intermediate values in An. gambiae s.s., but displaying no statistical difference. Evaluating differences in wing size and shape between LFA individuals and HFA ones, the wing size of HFA An. coluzzii was larger than that of LFAs during the wet season—its length was wider than predicted by allometry alone, indicating a change in wing shape. No statistically significant differences were found in the wing size/shape of An. gambiae s.s. or An. arabiensis. Conclusions The partial agreement between the tethered flight results and recent results based on aerial sampling of these species suggest a degree of discrimination between appetitive flyers and long-distance migrants although identifying HFAs as long-distance migrants is not recommended without further investigation.
Collapse
Affiliation(s)
- Roy Faiman
- Laboratory of Malaria and Vector Research, National Institute of Allergies and Infectious Diseases, The National Institutes of Health, Rockville, MD, USA.
| | - Alpha S Yaro
- Malaria Research and Training Center, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Moussa Diallo
- Malaria Research and Training Center, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Adama Dao
- Malaria Research and Training Center, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Samake Djibril
- Malaria Research and Training Center, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Zana L Sanogo
- Malaria Research and Training Center, Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Margery Sullivan
- Laboratory of Malaria and Vector Research, National Institute of Allergies and Infectious Diseases, The National Institutes of Health, Rockville, MD, USA
| | - Asha Krishna
- Laboratory of Malaria and Vector Research, National Institute of Allergies and Infectious Diseases, The National Institutes of Health, Rockville, MD, USA
| | - Benjamin J Krajacich
- Laboratory of Malaria and Vector Research, National Institute of Allergies and Infectious Diseases, The National Institutes of Health, Rockville, MD, USA
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, National Institute of Allergies and Infectious Diseases, The National Institutes of Health, Rockville, MD, USA
| |
Collapse
|
10
|
Burke AM, Brooke BD, Duncan FD. Metabolic rate does not vary with seasonal change in Anopheles arabiensis adults in South Africa. JOURNAL OF INSECT PHYSIOLOGY 2019; 118:103942. [PMID: 31505200 DOI: 10.1016/j.jinsphys.2019.103942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/24/2019] [Accepted: 09/06/2019] [Indexed: 06/10/2023]
Abstract
An important component of South Africa's malaria elimination agenda is identifying the entomological drivers of residual transmission, especially those that present opportunities for enhanced vector control. Seasonal mosquito density correlates directly with malaria transmission in South Africa. Transmission is highest during the warm rainy season and lowest but not entirely absent during the cooler dry season. The factors that sustain dry-season mosquito survival remain unknown. The aim of this project was therefore to investigate seasonal change in metabolic rate to determine the presence or absence of winter dormancy in malaria vector mosquitoes. Metabolic rate, determined by CO2 production during closed-system respirometry, was measured from wild anophelines collected from KwaZulu-Natal Province, South Africa. Monthly sampling spanned all four seasons (summer, autumn, winter, and spring) in 2017. Anopheles arabiensis and An. parensis specimens formed the majority of the total 437 identified specimens (n = 216 and n = 162, respectively). Metabolic rate data from wild-caught mosquitoes showed no significant seasonal disparities for An. arabiensis and An. parensis males and females. Further laboratory experiments assessed the effect of manipulated photoperiod, representing seasonal day-length changes, on the metabolic rate of colonized An. arabiensis mosquitoes. Simulations of midwinter (10 h:14 h light dark) and midsummer (14 h:10 h) day-length showed no significant effect on the metabolic rate of these mosquitoes. Age (in days) had a significant effect on the metabolic rate of both male and female colonized adult An. arabiensis mosquitoes which may be linked to developmental factors during maturation of adults. These data suggest that the South African populations of the malaria vector species An. arabiensis and An. parensis do not curtail their breeding and foraging activities during the colder and drier winter months. Overwintering by diapause does not appear to be triggered in the adult mosquito stage in An. arabiensis. However, their respective population densities do decrease considerably during winter leading to reduced malaria transmission and the opportunity for control by winter larviciding of known breeding sites.
Collapse
Affiliation(s)
- Ashley M Burke
- Wits Research Institute for Malaria and Wits/MRC Collaborating Centre for Multidisciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Basil D Brooke
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa; Wits Research Institute for Malaria and Wits/MRC Collaborating Centre for Multidisciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Frances D Duncan
- School of Animal, Plant & Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| |
Collapse
|
11
|
Huestis DL, Dao A, Diallo M, Sanogo ZL, Samake D, Yaro AS, Ousman Y, Linton YM, Krishna A, Veru L, Krajacich BJ, Faiman R, Florio J, Chapman JW, Reynolds DR, Weetman D, Mitchell R, Donnelly MJ, Talamas E, Chamorro L, Strobach E, Lehmann T. Windborne long-distance migration of malaria mosquitoes in the Sahel. Nature 2019; 574:404-408. [PMID: 31578527 PMCID: PMC11095661 DOI: 10.1038/s41586-019-1622-4] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 09/06/2019] [Indexed: 11/09/2022]
Abstract
Over the past two decades efforts to control malaria have halved the number of cases globally, yet burdens remain high in much of Africa and the elimination of malaria has not been achieved even in areas where extreme reductions have been sustained, such as South Africa1,2. Studies seeking to understand the paradoxical persistence of malaria in areas in which surface water is absent for 3-8 months of the year have suggested that some species of Anopheles mosquito use long-distance migration3. Here we confirm this hypothesis through aerial sampling of mosquitoes at 40-290 m above ground level and provide-to our knowledge-the first evidence of windborne migration of African malaria vectors, and consequently of the pathogens that they transmit. Ten species, including the primary malaria vector Anopheles coluzzii, were identified among 235 anopheline mosquitoes that were captured during 617 nocturnal aerial collections in the Sahel of Mali. Notably, females accounted for more than 80% of all of the mosquitoes that we collected. Of these, 90% had taken a blood meal before their migration, which implies that pathogens are probably transported over long distances by migrating females. The likelihood of capturing Anopheles species increased with altitude (the height of the sampling panel above ground level) and during the wet seasons, but variation between years and localities was minimal. Simulated trajectories of mosquito flights indicated that there would be mean nightly displacements of up to 300 km for 9-h flight durations. Annually, the estimated numbers of mosquitoes at altitude that cross a 100-km line perpendicular to the prevailing wind direction included 81,000 Anopheles gambiae sensu stricto, 6 million A. coluzzii and 44 million Anopheles squamosus. These results provide compelling evidence that millions of malaria vectors that have previously fed on blood frequently migrate over hundreds of kilometres, and thus almost certainly spread malaria over these distances. The successful elimination of malaria may therefore depend on whether the sources of migrant vectors can be identified and controlled.
Collapse
Affiliation(s)
- Diana L Huestis
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Adama Dao
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Zana L Sanogo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Djibril Samake
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Alpha S Yaro
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
- Faculte des Sciences et Techniques, Universite des Sciences des Techniques et des Technologies de Bamako (FSTUSTTB), Bamako, Mali
| | - Yossi Ousman
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Yvonne-Marie Linton
- Walter Reed Biosystematics Unit, Smithsonian Institution Museum Support Center, Suitland, MD, USA
- Department of Entomology, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Asha Krishna
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Laura Veru
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | | | - Roy Faiman
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Jenna Florio
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Jason W Chapman
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Environment and Sustainability Institute, University of Exeter, Penryn, UK
| | - Don R Reynolds
- Natural Resources Institute, University of Greenwich, Chatham, UK
- Rothamsted Research, Harpenden, UK
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Reed Mitchell
- Walter Reed Biosystematics Unit, Smithsonian Institution Museum Support Center, Suitland, MD, USA
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Elijah Talamas
- Systematic Entomology Laboratory - ARS, USDA, Smithsonian Institution National Museum of Natural History, Washington, DC, USA
- Florida Department of Agriculture and Consumer Services, Department of Plant Industry, Gainesville, FL, USA
| | - Lourdes Chamorro
- Department of Entomology, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
- Systematic Entomology Laboratory - ARS, USDA, Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - Ehud Strobach
- Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA
- Global Modeling and Assimilation Office, NASA GSFC, Greenbelt, MD, USA
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA.
| |
Collapse
|
12
|
North AR, Burt A, Godfray HCJ. Modelling the potential of genetic control of malaria mosquitoes at national scale. BMC Biol 2019; 17:26. [PMID: 30922310 PMCID: PMC6440076 DOI: 10.1186/s12915-019-0645-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 03/06/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The persistence of malaria in large parts of sub-Saharan Africa has motivated the development of novel tools to complement existing control programmes, including gene-drive technologies to modify mosquito vector populations. Here, we use a stochastic simulation model to explore the potential of using a driving-Y chromosome to suppress vector populations in a 106 km2 area of West Africa including all of Burkina Faso. RESULTS The consequence of driving-Y introductions is predicted to vary across the landscape, causing elimination of the target species in some regions and suppression in others. We explore how this variation is determined by environmental conditions, mosquito behaviour, and the properties of the gene-drive. Seasonality is particularly important, and we find population elimination is more likely in regions with mild dry seasons whereas suppression is more likely in regions with strong seasonality. CONCLUSIONS Despite the spatial heterogeneity, we suggest that repeated introductions of modified mosquitoes over a few years into a small fraction of human settlements may be sufficient to substantially reduce the overall number of mosquitoes across the entire geographic area.
Collapse
Affiliation(s)
- Ace R North
- Department of Zoology, University of Oxford, Oxford, UK.
| | | | | |
Collapse
|
13
|
Magombedze G, Ferguson NM, Ghani AC. A trade-off between dry season survival longevity and wet season high net reproduction can explain the persistence of Anopheles mosquitoes. Parasit Vectors 2018; 11:576. [PMID: 30390714 PMCID: PMC6215619 DOI: 10.1186/s13071-018-3158-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/17/2018] [Indexed: 11/17/2022] Open
Abstract
Background Plasmodium falciparum malaria remains a leading cause of death in tropical regions of the world. Despite efforts to reduce transmission, rebounds associated with the persistence of malaria vectors have remained a major impediment to local elimination. One area that remains poorly understood is how Anopheles populations survive long dry seasons to re-emerge following the onset of the rains. Methods We developed a suite of mathematical models to explore the impact of different dry-season mosquito survival strategies on the dynamics of vector populations. We fitted these models to an Anopheles population data set from Mali to estimate the model parameters and evaluate whether incorporating aestivation improved the fit of the model to the observed seasonal dynamics. We used the fitted models to explore the impact of intervention strategies that target aestivating mosquitoes in addition to targeting active mosquitoes and larvae. Results Including aestivation in the model significantly improved our ability to reproduce the observed seasonal dynamics of vector populations as judged by the deviance information criterion (DIC). Furthermore, such a model resulted in more biologically plausible active mosquito survival times (for A. coluzzii median wet season survival time of 10.9 days, 95% credible interval (CrI): 10.0–14.5 days in a model with aestivation versus 38.1 days, 95% CrI: 35.8–42.5 days in a model without aestivation; similar patterns were observed for A. arabiensis). Aestivation also generated enhanced persistence of the vector population over a wider range of both survival times and fecundity levels. Adding vector control interventions that target the aestivating mosquito population is shown to have the potential to enhance the impact of existing vector control. Conclusions Dry season survival attributes appear to drive vector population persistence and therefore have implications for vector control. Further research is therefore needed to better understand these mechanisms and to evaluate the additional benefit of vector control strategies that specifically target dormant mosquitoes. Electronic supplementary material The online version of this article (10.1186/s13071-018-3158-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Gesham Magombedze
- Center for Infectious Diseases Research and Experimental Therapeutics, Baylor Research Institute, Baylor University Medical Center, Dallas, TX, USA. .,MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Neil M Ferguson
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| |
Collapse
|
14
|
Dehydration prompts increased activity and blood feeding by mosquitoes. Sci Rep 2018; 8:6804. [PMID: 29717151 PMCID: PMC5931509 DOI: 10.1038/s41598-018-24893-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 04/11/2018] [Indexed: 11/27/2022] Open
Abstract
Current insights into the mosquito dehydration response rely on studies that examine specific responses but ultimately fail to provide an encompassing view of mosquito biology. Here, we examined underlying changes in the biology of mosquitoes associated with dehydration. Specifically, we show that dehydration increases blood feeding in the northern house mosquito, Culex pipiens, which was the result of both higher activity and a greater tendency to land on a host. Similar observations were noted for Aedes aegypti and Anopheles quadrimaculatus. RNA-seq and metabolome analyses in C. pipiens following dehydration revealed that factors associated with carbohydrate metabolism are altered, specifically the breakdown of trehalose. Suppression of trehalose breakdown in C. pipiens by RNA interference reduced phenotypes associated with lower hydration levels. Lastly, mesocosm studies for C. pipiens confirmed that dehydrated mosquitoes were more likely to host feed under ecologically relevant conditions. Disease modeling indicates dehydration bouts will likely enhance viral transmission. This dehydration-induced increase in blood feeding is therefore likely to occur regularly and intensify during periods when availability of water is low.
Collapse
|
15
|
North AR, Godfray HCJ. Modelling the persistence of mosquito vectors of malaria in Burkina Faso. Malar J 2018; 17:140. [PMID: 29609598 PMCID: PMC5879775 DOI: 10.1186/s12936-018-2288-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 03/21/2018] [Indexed: 11/26/2022] Open
Abstract
Background Populations of the Anopheles gambiae complex are found during the rainy season throughout West Africa, even in arid areas with long dry seasons during which mosquitoes appear to be absent. Several hypotheses have been proposed to explain this apparent paradox, including aestivation, dispersal between neighbouring settlements, and long distance migration using high-altitude wind currents. Methods An individual-based, spatially explicit model of mosquito populations was developed for a region of West Africa centred on, and including all of, Burkina Faso. Populations associated with human settlements were linked by dispersal and the model incorporated geospatial data on the distribution of settlements, water bodies and rainfall. Results Local dispersal (at rates consistent with experimental data) was necessary to explain observed patterns of rainy season populations across all of the simulation area, but by itself failed to account for the presence of populations in the arid North (the Sahel). The presence of rare dry-season larval sites could explain these northern populations, but seems inconsistent with field surveys. Aestivation by female mosquitoes explained rainy-season populations in all but the very sparsest and driest areas of human habitation, while long-distance migration based on annual wind patterns could account for all observed populations. Conclusions Modelling studies such as this can help assess the potential validity of different hypotheses and suggest priority areas for experimental study. In particular, the results highlight a shortage of empirical research on mosquito dispersal between neighbouring settlements, which may be critically important to the continued presence of many mosquito populations in West Africa. Further research that establishes the extent to which mosquitoes aestivate, and migrate using high altitude winds, is also much needed to understand Sahelian mosquito populations. Electronic supplementary material The online version of this article (10.1186/s12936-018-2288-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Ace R North
- Department of Zoology, University of Oxford, Woodstock Road, Oxford, OX2 6GG, UK.
| | - H Charles J Godfray
- Department of Zoology, University of Oxford, Woodstock Road, Oxford, OX2 6GG, UK
| |
Collapse
|
16
|
Krajacich BJ, Huestis DL, Dao A, Yaro AS, Diallo M, Krishna A, Xu J, Lehmann T. Investigation of the seasonal microbiome of Anopheles coluzzii mosquitoes in Mali. PLoS One 2018; 13:e0194899. [PMID: 29596468 PMCID: PMC5875798 DOI: 10.1371/journal.pone.0194899] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/12/2018] [Indexed: 01/08/2023] Open
Abstract
The poorly understood mechanisms of dry season persistence of Anopheles spp. mosquitoes through the dry season in Africa remain a critical gap in our knowledge of Plasmodium disease transmission. While it is thought that adult mosquitoes remain in a dormant state throughout this seven-month dry season, the nature of this state remains unknown and has largely not been recapitulated in laboratory settings. To elucidate possible connections of this state with microbial composition, the whole body microbiomes of adult mosquitoes in the dry and wet seasons in two locations of Mali with varying water availability were compared by sequencing the 16S ribosomal RNA gene. These locations were a village near the Niger River with year-round water sources (N’Gabakoro, “riparian”), and a typical Sahelian area with highly seasonal breeding sites (Thierola Area, “Sahelian”). The 16S bacterial data consisted of 2057 sequence variants in 426 genera across 184 families. From these data, we found several compositional differences that were seasonally and spatially linked. Counter to our initial hypothesis, there were more pronounced seasonal differences in the bacterial microbiome of riparian, rather than Sahelian areas. These seasonal shifts were primarily in Ralstonia, Sphingorhabdus, and Duganella spp. bacteria that are usually soil and water-associated, indicating these changes may be from bacteria acquired in the larval environment, rather than adulthood. In Sahelian dry season mosquitoes, there was a unique intracellular bacteria, Anaplasma, which likely was acquired through non-human blood feeding. Cytochrome B analysis of blood meals showed greater heterogeneity in host choice of An. coluzzii independent of season in the Thierola area compared to N’Gabakoro (77.5% vs. 94.6% human-origin blood meal, respectively), indicating a relaxation of anthropophily. Overall, this exploratory study provides valuable indications of spatial and seasonal differences in bacterial composition which help refine this difficult to study state.
Collapse
Affiliation(s)
- Benjamin J. Krajacich
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, Maryland, United States of America
- * E-mail: (BJK); (TL)
| | - Diana L. Huestis
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, Maryland, United States of America
| | - Adama Dao
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Alpha S. Yaro
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Asha Krishna
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, Maryland, United States of America
| | - Jiannong Xu
- Biology Department, New Mexico State University, Las Cruces, New Mexico, United states of America
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, Maryland, United States of America
- * E-mail: (BJK); (TL)
| |
Collapse
|
17
|
Hidalgo K, Montazeau C, Siaussat D, Braman V, Trabalon M, Simard F, Renault D, Dabiré RK, Mouline K. Distinct physiological, biochemical and morphometric adjustments in the malaria vectors Anopheles gambiae and A. coluzzii as means to survive dry season conditions in Burkina Faso. ACTA ACUST UNITED AC 2018; 221:jeb.174433. [PMID: 29378815 DOI: 10.1242/jeb.174433] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 01/17/2018] [Indexed: 01/17/2023]
Abstract
Aestivation and dispersive migration are the two strategies evoked in the literature to explain the way in which malaria vectors Anopheles coluzzii and A. gambiae survive the harsh climatic conditions of the dry season in sub-Saharan Africa. However, the physiological mechanisms regulating these two strategies are unknown. In the present study, mosquito species were exposed to controlled environmental conditions mimicking the rainy and dry seasons of south western Burkina Faso. Survival strategies were studied through morphometric (wing length), ecophysiological (respiratory gas exchanges), biochemical (cuticular hydrocarbons composition) and molecular (AKH mRNA expression levels) parameters, variations of which are usually considered to be hallmarks of aestivation and dispersion mechanisms in various insects. Our results showed that ecophysiological and morphometric adjustments are made in both species to prevent water losses during the dry season. However, the usual metabolic rate modifications expected as signatures of aestivation and migration were not observed, highlighting specific and original physiological mechanisms sustaining survival in malaria mosquitoes during the dry season. Differences in epicuticular hydrocarbon composition and AKH levels of expression were found between the permanent and temporary A. coluzzii populations, illustrating the great phenotypic plasticity of this mosquito species. Altogether, our work underlines the diverse and complex pattern of changes occurring in the two mosquito species and at the population level to cope with the dry season and highlights potential targets of future control tools.
Collapse
Affiliation(s)
- K Hidalgo
- Université de Rennes 1, UMR CNRS 6553 Ecobio, Campus de Beaulieu, 263 Avenue du General Leclerc, CS 74205 35042 Rennes, Cedex, France .,INRA UR370 QuaPA, MASS Group, 63122 Saint-Genès-Champanelle, France
| | - C Montazeau
- Institut de Recherche pour le Développement (IRD), UMR IRD 224-CNRS 5290-Université de Montpellier 1-Université de Montpellier 2 MIVEGEC, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, Cedex 5, France
| | - D Siaussat
- UMR 7618 Institute of Ecology and Environmental Sciences of Paris, Department of Sensory Ecology, Université Pierre et Marie Curie (UPMC), 4 Place Jussieu, Tour 44-45, 3ème étage, 75005 Paris, France
| | - V Braman
- UMR 7618 Institute of Ecology and Environmental Sciences of Paris, Department of Sensory Ecology, Université Pierre et Marie Curie (UPMC), 4 Place Jussieu, Tour 44-45, 3ème étage, 75005 Paris, France
| | - M Trabalon
- Université de Rennes 1, UMR CNRS 6552 Ethologie animale et humaine, Campus de Beaulieu, 263 Avenue du General Leclerc, 35042 Rennes, Cedex, France
| | - F Simard
- Institut de Recherche pour le Développement (IRD), UMR IRD 224-CNRS 5290-Université de Montpellier 1-Université de Montpellier 2 MIVEGEC, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, Cedex 5, France
| | - D Renault
- Université de Rennes 1, UMR CNRS 6553 Ecobio, Campus de Beaulieu, 263 Avenue du General Leclerc, CS 74205 35042 Rennes, Cedex, France.,Institut Universitaire de France, 1 rue Descartes, 75231 Paris, Cedex 05, France
| | - R K Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso
| | - K Mouline
- Institut de Recherche pour le Développement (IRD), UMR IRD 224-CNRS 5290-Université de Montpellier 1-Université de Montpellier 2 MIVEGEC, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, Cedex 5, France.,Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso
| |
Collapse
|
18
|
Huestis DL, Artis ML, Armbruster PA, Lehmann T. Photoperiodic responses of Sahelian malaria mosquitoes Anopheles coluzzii and An. arabiensis. Parasit Vectors 2017; 10:621. [PMID: 29282150 PMCID: PMC5745990 DOI: 10.1186/s13071-017-2556-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 11/26/2017] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Throughout large parts of sub-Saharan Africa, seasonal malaria transmission follows mosquito density, approaching zero during the dry season and peaking during the wet season. The mechanisms by which malaria mosquitoes survive the long dry season, when no larval sites are available remain largely unknown, despite being long recognized as a critical target for vector control. Previous work in the West African Sahel has led to the hypothesis that Anopheles coluzzii (formerly M-form Anopheles gambiae) undergoes aestivation (dry-season diapause), while Anopheles gambiae (s.s.) (formerly S-form An. gambiae) and Anopheles arabiensis repopulate each wet season via long-distance migration. The environmental cues used by these species to signal the oncoming dry season have not been determined; however, studies, mostly addressing mosquitoes from temperate zones, have highlighted photoperiod and temperature as the most common token stimuli for diapause initiation. We subjected newly established colonies of An. coluzzii and An. arabiensis from the Sahel to changes in photoperiod to assess and compare their responses in terms of longevity and other relevant phenotypes. RESULTS Our results showed that short photoperiod alone and to a lesser extent, lower nightly temperature (representing the early dry season), significantly increased longevity of An. coluzzii (by ~30%, P < 0.001) but not of An. arabiensis. Further, dry season conditions increased body size but not relative lipid content of An. coluzzii, whereas body size of An. arabiensis decreased under these conditions. CONCLUSIONS These species-specific responses underscore the capacity of tropical anophelines to detect mild changes (~1 h) in photoperiod and thus support the role of photoperiod as a token stimulus for An. coluzzii in induction of aestivation, although, these responses fall short of a complete recapitulation of aestivation under laboratory conditions.
Collapse
Affiliation(s)
- Diana L. Huestis
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD USA
| | - Monica L. Artis
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD USA
| | | | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD USA
| |
Collapse
|
19
|
Simões PMV, Gibson G, Russell IJ. Pre-copula acoustic behaviour of males in the malarial mosquitoes Anopheles coluzzii and Anopheles gambiae s.s. does not contribute to reproductive isolation. ACTA ACUST UNITED AC 2017; 220:379-385. [PMID: 28148817 DOI: 10.1242/jeb.149757] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 11/09/2016] [Indexed: 11/20/2022]
Abstract
We reveal that males of two members of the Anopheles gambiae s.l. species complex, Anopheles coluzzii and Anopheles gambiae s.s. (hereafter A. gambiae), which are both malaria vectors, perform a stereotypical acoustic behaviour in response to pure tones at frequencies that encompass the frequency range of the female's flight-tones. This behaviour resembles that described for Culex quinquefasciatus and consists of phonotactic flight initiated by a steep increase in wing-beat frequency (WBF) followed by rapid frequency modulation (RFM) of WBF when in close proximity to the sound source. RFM was elicited without acoustic feedback or the presence of a live female, but it appears to be a stereotypic behaviour in the immediate lead up to copula formation. RFM is an independent and different behavioural process from harmonic convergence interactions used by male-female pairs for mate recognition at earlier stages of mating. Acoustic threshold for RFM was used to plot behavioural audiograms from free-flying A coluzzii and A gambiae males. These audiograms were almost identical (minima ∼400 Hz) and encompassed the WBF ranges of A coluzzii (378-601 Hz) and A gambiae (373-590 Hz) females, indicating that males of the two species share similar frequency tuning and range. Furthermore, no differences were found between the two species in their WBFs, RFM behaviour or harmonic convergence ratios. These results indicate that assortative mating between A coluzzii and A gambiae is unlikely to be based on male-specific acoustic behaviours during RFM. The significance of these findings in relation to possible mechanisms for assortative mating is discussed.
Collapse
Affiliation(s)
- Patrício M V Simões
- Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK
| | - Gabriella Gibson
- Department of Agriculture, Health and Environment, Natural Resources Institute, University of Greenwich, Chatham, Kent ME4 4TB, UK
| | - Ian J Russell
- Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK
| |
Collapse
|
20
|
Lehmann T, Weetman D, Huestis DL, Yaro AS, Kassogue Y, Diallo M, Donnelly MJ, Dao A. Tracing the origin of the early wet-season Anopheles coluzzii in the Sahel. Evol Appl 2017; 10:704-717. [PMID: 28717390 PMCID: PMC5511357 DOI: 10.1111/eva.12486] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 02/24/2017] [Indexed: 11/29/2022] Open
Abstract
In arid environments, the source of the malaria mosquito populations that re‐establish soon after first rains remains a puzzle and alternative explanations have been proposed. Using genetic data, we evaluated whether the early rainy season (RS) population of Anopheles coluzzii is descended from the preceding late RS generation at the same locality, consistent with dry season (DS) dormancy (aestivation), or from migrants from distant locations. Distinct predictions derived from these two hypotheses were assessed, based on variation in 738 SNPs in eleven A. coluzzii samples, including seven samples spanning 2 years in a Sahelian village. As predicted by the “local origin under aestivation hypothesis,” temporal samples from the late RS and those collected after the first rain of the following RS were clustered together, while larger genetic distances were found among samples spanning the RS. Likewise, multilocus genotype composition of samples from the end of the RS was similar across samples until the following RS, unlike samples that spanned the RS. Consistent with reproductive arrest during the DS, no genetic drift was detected between samples taken over that period, despite encompassing extreme population minima, whereas it was detected between samples spanning the RS. Accordingly, the variance in allele frequency increased with time over the RS, but not over the DS. However, not all the results agreed with aestivation. Large genetic distances separated samples taken a year apart, and during the first year, within‐sample genetic diversity declined and increased back during the late RS, suggesting a bottleneck followed by migration. The decline of genetic diversity followed by a mass distribution of insecticide‐treated nets was accompanied by a reduced mosquito density and a rise in the mutation conferring resistance to pyrethroids, indicating a bottleneck due to insecticidal selection. Overall, our results support aestivation in A. coluzzii during the DS that is accompanied by long‐distance migration in the late RS.
Collapse
Affiliation(s)
- Tovi Lehmann
- Laboratory of Malaria and Vector Research NIAID, NIH Rockville MD USA
| | - David Weetman
- Department of Vector Biology Liverpool School of Tropical Medicine Liverpool UK
| | - Diana L Huestis
- Laboratory of Malaria and Vector Research NIAID, NIH Rockville MD USA
| | - Alpha S Yaro
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
| | - Yaya Kassogue
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
| | - Martin J Donnelly
- Department of Vector Biology Liverpool School of Tropical Medicine Liverpool UK
| | - Adama Dao
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
| |
Collapse
|
21
|
Faiman R, Solon-Biet S, Sullivan M, Huestis DL, Lehmann T. The contribution of dietary restriction to extended longevity in the malaria vector Anopheles coluzzii. Parasit Vectors 2017; 10:156. [PMID: 28340627 PMCID: PMC5366120 DOI: 10.1186/s13071-017-2088-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/14/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Variation in longevity has long been of interest in vector biology because of its implication in disease transmission through vectorial capacity. Recent studies suggest that Anopheles coluzzii adults persist during the ~7 month dry season via aestivation. Recently there has been a growing body of evidence linking dietary restriction and low ratio of dietary protein to carbohydrate with extended longevity of animals. Here, we evaluated the effects of dietary restriction and the protein : carbohydrate ratio on longevity of An. coluzzii. RESULTS In our experiment, we combined dietary regimes with temperature and relative humidity to assess their effects on An. coluzzii longevity, in an attempt to simulate aestivation under laboratory conditions. Our results showed significant effects of both the physical and the dietary variables on longevity, but that diet regimen had a considerably greater effect than those of the physical conditions. Higher temperature and lower humidity reduced longevity. At 22 °C dietary protein (blood) shortened longevity when sugar was not restricted (RH = 85%), but extended longevity when sugar was restricted (RH = 50%). CONCLUSIONS Dietary restriction extended longevity in accord with predictions, but protein : carbohydrate ratio had a negligible effect. We identified conditions that significantly extend longevity in malaria vectors, however, the extent of increase in longevity was insufficient to simulate aestivation.
Collapse
Affiliation(s)
- Roy Faiman
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, 20852, USA.
| | | | - Margery Sullivan
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, 20852, USA
| | - Diana L Huestis
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, 20852, USA.,Office of Global Health Diplomacy, U.S. Department of State, 1800 G Street NW, Suite 10300, Washington, DC, 20006, USA
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, 20852, USA
| |
Collapse
|
22
|
Arcaz AC, Huestis DL, Dao A, Yaro AS, Diallo M, Andersen J, Blomquist GJ, Lehmann T. Desiccation tolerance in Anopheles coluzzii: the effects of spiracle size and cuticular hydrocarbons. ACTA ACUST UNITED AC 2016; 219:1675-88. [PMID: 27207644 PMCID: PMC4920233 DOI: 10.1242/jeb.135665] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/09/2016] [Indexed: 01/08/2023]
Abstract
The African malaria mosquitoes Anopheles gambiae and Anopheles coluzzii range over forests and arid areas, where they withstand dry spells and months-long dry seasons, suggesting variation in their desiccation tolerance. We subjected a laboratory colony (G3) and wild Sahelian mosquitoes during the rainy and dry seasons to desiccation assays. The thoracic spiracles and amount and composition of cuticular hydrocarbons (CHCs) of individual mosquitoes were measured to determine the effects of these traits on desiccation tolerance. The relative humidity of the assay, body water available, rate of water loss and water content at death accounted for 88% of the variation in desiccation tolerance. Spiracle size did not affect the rate of water loss or desiccation tolerance of the colony mosquitoes, as was the case for the total CHCs. However, six CHCs accounted for 71% of the variation in desiccation tolerance and three accounted for 72% of the variation in the rate of water loss. Wild A. coluzzii exhibited elevated desiccation tolerance during the dry season. During that time, relative thorax and spiracle sizes were smaller than during the rainy season. A smaller spiracle size appeared to increase A. coluzzii's desiccation tolerance, but was not statistically significant. Seasonal changes in CHC composition were detected in Sahelian A. coluzzii Stepwise regression models suggested the effect of particular CHCs on desiccation tolerance. In conclusion, the combination of particular CHCs along with the total amount of CHCs is a primary mechanism conferring desiccation tolerance in A. coluzzii, while variation in spiracle size might be a secondary mechanism.
Collapse
Affiliation(s)
- Arthur C Arcaz
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD 20852, USA
| | - Diana L Huestis
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD 20852, USA
| | - Adama Dao
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, Bamako, BP 1805, Mali
| | - Alpha S Yaro
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, Bamako, BP 1805, Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC)/Faculty of Medicine, Pharmacy and Odonto-stomatology, Bamako, BP 1805, Mali
| | - John Andersen
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD 20852, USA
| | - Gary J Blomquist
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD 20852, USA
| |
Collapse
|
23
|
Mamai W, Mouline K, Parvy JP, Le Lannic J, Dabiré KR, Ouédraogo GA, Renault D, Simard F. Morphological changes in the spiracles of Anopheles gambiae s.l (Diptera) as a response to the dry season conditions in Burkina Faso (West Africa). Parasit Vectors 2016; 9:11. [PMID: 26739500 PMCID: PMC4704408 DOI: 10.1186/s13071-015-1289-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 12/25/2015] [Indexed: 11/26/2022] Open
Abstract
Background Survival to dry season conditions of sub-Saharan savannahs is a major challenge for insects inhabiting such environments, especially regarding the desiccation threat they are exposed to. While extensive literature about insect seasonality has revealed morphologic, metabolic and physiological changes in many species, only a few studies have explored the responses following exposure to the stressful dry season conditions in major malaria vectors. Here, we explored morphological changes triggered by exposure to dry season conditions in An. gambiae s.l. mosquitoes by comparing females reared in climatic chambers reflecting environmental conditions found in mosquito habitats during the rainy and dry seasons in a savannah area of Burkina Faso (West Africa). Results Using scanning electron microscopy (SEM) and confocal imaging, we revealed significant changes in morphological features of the spiracles in females An. gambiae s.l. exposed to contrasted environmental conditions. Hence, the hairs surrounding the spiracles were thicker in the three species when raised under dry season environmental conditions. The thicker hairs were in some cases totally obstructing spiracular openings. Specific staining provided evidence against contamination by external microorganisms such as bacteria and fungi. However, only further analysis would unequivocally rule out the hypothesis of experimental artifact. Conclusion Morphological changes in spiracular features probably help to limit body water loss during desiccating conditions, therefore contributing to insect survival. Differences between species within the An. gambiae complex might therefore reflect different survival strategies used by these species to overcome the detrimental dry season conditions in the wild. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-1289-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Wadaka Mamai
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso. .,MIVEGEC, UMR IRD 224-CNRS 5290-Université de Montpellier, Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, 34394, Montpellier, cedex 5, France. .,Université Polytechnique de Bobo-Dioulasso (UPB), Bobo-Dioulasso, Burkina Faso. .,Institut de Recherche pour le Développement, Antenne de Bobo Dioulasso, BP 171, Bobo Dioulasso 01, Burkina Faso.
| | - Karine Mouline
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso. .,MIVEGEC, UMR IRD 224-CNRS 5290-Université de Montpellier, Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, 34394, Montpellier, cedex 5, France.
| | - Jean-Philippe Parvy
- Université Pierre et Marie Curie, 75005, Paris, France. .,CGM, UPR 3404, CNRS, 91190, Gif-sur-Yvette, France.
| | - Jo Le Lannic
- Université de Rennes 1, UMR CNRS 6553 ECOBIO, Campus de Beaulieu, 263 Avenue du Gal Leclerc, CS 74205 35042, Rennes, Cedex, France.
| | - Kounbobr Roch Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso.
| | | | - David Renault
- Université de Rennes 1, UMR CNRS 6553 ECOBIO, Campus de Beaulieu, 263 Avenue du Gal Leclerc, CS 74205 35042, Rennes, Cedex, France.
| | - Frederic Simard
- MIVEGEC, UMR IRD 224-CNRS 5290-Université de Montpellier, Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, 34394, Montpellier, cedex 5, France.
| |
Collapse
|
24
|
Hidalgo K, Dujardin JP, Mouline K, Dabiré RK, Renault D, Simard F. Seasonal variation in wing size and shape between geographic populations of the malaria vector, Anopheles coluzzii in Burkina Faso (West Africa). Acta Trop 2015; 143:79-88. [PMID: 25579425 DOI: 10.1016/j.actatropica.2014.12.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 12/16/2014] [Accepted: 12/26/2014] [Indexed: 11/24/2022]
Abstract
The mosquito, Anopheles coluzzii is a major vector of human malaria in Africa with widespread distribution throughout the continent. The species hence populates a wide range of environments in contrasted ecological settings often exposed to strong seasonal fluctuations. In the dry savannahs of West Africa, this mosquito population dynamics closely follows the pace of surface water availability: the species pullulates during the rainy season and is able to reproduce throughout the dry season in areas where permanent water bodies are available for breeding. The impact of such environmental fluctuation on mosquito development and the phenotypic quality of emerging adults has however not been addressed in details. Here, we examined and compared phenotypic changes in the duration of pre-imaginal development, body dry mass at emergence and wing size, shape and surface area in young adult females An. coluzzii originated from five distinct geographic locations when they are reared in two contrasting conditions mimicking those experienced by mosquitoes during the rainy season (RS) and at the onset of the dry season (ODS) in Burkina Faso (West Africa). Our results demonstrated strong phenotypic plasticity in all traits, with differences in the magnitude and direction of changes between RS and ODS depending upon the geographic origin, hence the genetic background of the mosquito populations. Highest heterogeneity within population was observed in Bama, where large irrigation schemes allow year-round mosquito breeding. Further studies are needed to explore the adaptive value of such phenotypic plasticity and its relevance for local adaptation in An. coluzzii.
Collapse
|
25
|
Aboud M, Makhawi A, Verardi A, El Raba’a F, Elnaiem DE, Townson H. A genotypically distinct, melanic variant of Anopheles arabiensis in Sudan is associated with arid environments. Malar J 2014; 13:492. [PMID: 25496059 PMCID: PMC4301653 DOI: 10.1186/1475-2875-13-492] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 12/06/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Anopheles arabiensis, an important malaria vector in Sudan and other countries in sub-Saharan Africa, exhibits considerable ecological and behavioural plasticity allowing it to survive in the harsh conditions of arid regions. It has been shown that adult populations of An. arabiensis in the semi-desert habitat of western Khartoum State survive through the long dry season in a state of partial aestivation, characterized by limited feeding activity and a degree of arrested ovarian development. Anopheles arabiensis in these sites occurs in two phenotypic forms. One is large and heavily melanized, the other has the typical characteristics of An. arabiensis as found elsewhere in Africa. The extent of genetic variation in these forms was examined in widely separated locations in Sudan, including Kassala, Gedaref and the Northern States between 1998 and 1999 and 2004 and 2006. METHODS Each mosquito specimen was identified using standard morphological keys and a species-specific PCR test. Sequence variation in a 660 bp fragment of the mtDNA ND5 coding region was examined and the extent of genetic divergence between the forms was estimated from FST values using DNASP version 4.9. TCS 1.13 software was used to determine the genealogical relationships and to reflect clustering among mtDNA haplotypes. RESULTS The melanic and normal forms were found in sympatry in Kassala, Gedaref and Khartoum states, with the melanic form commonest in the hottest and most arid areas. Both forms were encountered in the periods of study: 1998-1999, and 2004-2006. Only ten specimens of An. arabiensis were collected from the Northern State in February 2006, all of which were of the normal form.Based on the ND5 analysis, there was a marked subdivision between the normal and melanic forms (FST = 0.59). Furthermore, the melanic form showed more genetic variability, as measured by haplotype diversity (0.95) compared with the normal form (0.57), suggesting larger effective population. CONCLUSIONS This is the first demonstration of correspondent phenotypic and genetic structuring in An. arabiensis. The high level of genetic differentiation shown by the mtDNA ND5 locus suggests that the two forms may represent separate species. It is hypothesized that the melanic form is better adapted to hot and arid environments.
Collapse
Affiliation(s)
- Mariam Aboud
- />Department of Biology, Faculty of Science and Technology, Al-Neelain University, Khartoum, Sudan
| | - Abdelrafie Makhawi
- />Department of Biotechnology, College of Applied and Industrial Sciences, University of Bahri, Khartoum, Sudan
| | - Andrea Verardi
- />Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA UK
| | - Fathi El Raba’a
- />Department of Zoology, University of Khartoum, P.O. Box 321, Khartoum, Sudan
| | - Dia-Eldin Elnaiem
- />Department of Natural Sciences, University of Maryland Eastern Shore, 1 Backbone Rd, Princess Anne, MD 20851 USA
| | - Harold Townson
- />Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA UK
| |
Collapse
|
26
|
Signatures of aestivation and migration in Sahelian malaria mosquito populations. Nature 2014; 516:387-90. [PMID: 25470038 PMCID: PMC4306333 DOI: 10.1038/nature13987] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/22/2014] [Indexed: 11/08/2022]
Abstract
During the long Sahelian dry season, mosquito vectors of malaria are expected to perish when no larval sites are available; yet, days after the first rains, mosquitoes reappear in large numbers. How these vectors persist over the 3-6-month long dry season has not been resolved, despite extensive research for over a century. Hypotheses for vector persistence include dry-season diapause (aestivation) and long-distance migration (LDM); both are facets of vector biology that have been highly controversial owing to lack of concrete evidence. Here we show that certain species persist by a form of aestivation, while others engage in LDM. Using time-series analyses, the seasonal cycles of Anopheles coluzzii, Anopheles gambiae sensu stricto (s.s.), and Anopheles arabiensis were estimated, and their effects were found to be significant, stable and highly species-specific. Contrary to all expectations, the most complex dynamics occurred during the dry season, when the density of A. coluzzii fluctuated markedly, peaking when migration would seem highly unlikely, whereas A. gambiae s.s. was undetected. The population growth of A. coluzzii followed the first rains closely, consistent with aestivation, whereas the growth phase of both A. gambiae s.s. and A. arabiensis lagged by two months. Such a delay is incompatible with local persistence, but fits LDM. Surviving the long dry season in situ allows A. coluzzii to predominate and form the primary force of malaria transmission. Our results reveal profound ecological divergence between A. coluzzii and A. gambiae s.s., whose standing as distinct species has been challenged, and suggest that climate is one of the selective pressures that led to their speciation. Incorporating vector dormancy and LDM is key to predicting shifts in the range of malaria due to global climate change, and to the elimination of malaria from Africa.
Collapse
|
27
|
Hidalgo K, Mouline K, Mamai W, Foucreau N, Dabiré KR, Bouchereau A, Simard F, Renault D. Novel insights into the metabolic and biochemical underpinnings assisting dry-season survival in female malaria mosquitoes of the Anopheles gambiae complex. JOURNAL OF INSECT PHYSIOLOGY 2014; 70:102-116. [PMID: 25083809 DOI: 10.1016/j.jinsphys.2014.07.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 06/05/2014] [Accepted: 07/21/2014] [Indexed: 06/03/2023]
Abstract
The mechanisms by which Anopheles gambiae mosquitoes survive the desiccating conditions of the dry season in Africa and are able to readily transmit malaria soon after the rains start remain largely unknown. The desiccation tolerance and resistance of female An. gambiae M and S reared in contrasting environmental conditions reflecting the onset of dry season ("ods") and the rainy season ("rs") was determined by monitoring their survival and body water loss in response to low relative humidity. Furthermore, we investigated the degree to which the physiology of 1-h and 24-h-old females is altered at "ods" by examining and comparing their quantitative metabotypes and proteotypes with conspecifics exposed to "rs" conditions. Results showed that distinct biochemical rearrangements occurred soon after emergence in female mosquitoes that enhance survival and limit water loss under dry conditions. In particular, three amino acids (phenylalanine, tyrosine, and valine) playing a pivotal role in cuticle permeability decreased significantly from the 1-h to 24-h-old females, regardless of the experimental conditions. However, these amino acids were present in higher amounts in 1-h-old female An. gambiae M reared under "ods" whereas no such seasonal difference was reported in S ones. Together with the 1.28- to 2.84-fold increased expression of cuticular proteins 70 and 117, our data suggests that cuticle composition, rigidity and permeability were adjusted at "ods". Increased expression of enzymes involved in glycogenolytic and proteolytic processes were found in both forms at "ods". Moreover, 1-h-old S forms were characterised by elevated amounts of glycogen phosphorylase, isocitrate dehydrogenase, and citrate synthase, suggesting an increase of energetic demand in these females at "ods".
Collapse
Affiliation(s)
- K Hidalgo
- Université de Rennes 1, UMR CNRS 6553 Ecobio, Campus de Beaulieu, 263 Avenue du Général Leclerc, CS 74205, 35042 Rennes Cedex, France; Institut de Recherche pour le Développement (IRD), UMR IRD 224-CNRS 5290-Université de Montpellier 1, Université de Montpellier 2 MIVEGEC, 911 Avenue Agropolis, BP 64501, 34394 Montpellier cedex 5, France.
| | - K Mouline
- Institut de Recherche pour le Développement (IRD), UMR IRD 224-CNRS 5290-Université de Montpellier 1, Université de Montpellier 2 MIVEGEC, 911 Avenue Agropolis, BP 64501, 34394 Montpellier cedex 5, France; Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso
| | - W Mamai
- Institut de Recherche pour le Développement (IRD), UMR IRD 224-CNRS 5290-Université de Montpellier 1, Université de Montpellier 2 MIVEGEC, 911 Avenue Agropolis, BP 64501, 34394 Montpellier cedex 5, France; Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso
| | - N Foucreau
- Université Claude Bernard Lyon 1, UMR CNRS 5023 LEHNA, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France
| | - K R Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso
| | - A Bouchereau
- Université de Rennes 1, UMR INRA IGEPP, Campus de Beaulieu, 263 Avenue du Général Leclerc, CS 74205, 35042 Rennes Cedex, France
| | - F Simard
- Institut de Recherche pour le Développement (IRD), UMR IRD 224-CNRS 5290-Université de Montpellier 1, Université de Montpellier 2 MIVEGEC, 911 Avenue Agropolis, BP 64501, 34394 Montpellier cedex 5, France
| | - D Renault
- Université de Rennes 1, UMR CNRS 6553 Ecobio, Campus de Beaulieu, 263 Avenue du Général Leclerc, CS 74205, 35042 Rennes Cedex, France
| |
Collapse
|
28
|
Wagoner KM, Lehmann T, Huestis DL, Ehrmann BM, Cech NB, Wasserberg G. Identification of morphological and chemical markers of dry- and wet-season conditions in female Anopheles gambiae mosquitoes. Parasit Vectors 2014; 7:294. [PMID: 24970701 PMCID: PMC4099382 DOI: 10.1186/1756-3305-7-294] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 06/11/2014] [Indexed: 11/30/2022] Open
Abstract
Background Increased understanding of the dry-season survival mechanisms of Anopheles gambiae in semi-arid regions could benefit vector control efforts by identifying weak links in the transmission cycle of malaria. In this study, we examined the effect of photoperiod and relative humidity on morphologic and chemical traits known to control water loss in mosquitoes. Methods Anopheles gambiae body size (indexed by wing length), mesothoracic spiracle size, and cuticular hydrocarbon composition (both standardized by body size) were examined in mosquitoes raised from eggs exposed to short photoperiod and low relative humidity, simulating the dry season, or long photoperiod and high relative humidity, simulating the wet-season. Results Mosquitoes exposed to short photoperiod exhibited larger body size and larger mesothoracic spiracle length than mosquitoes exposed to long photoperiod. Mosquitoes exposed to short photoperiod and low relative humidity exhibited greater total cuticular hydrocarbon amount than mosquitoes exposed to long photoperiod and high relative humidity. In addition, total cuticular hydrocarbon amount increased with age and was higher in mated females. Mean n-alkane retention time (a measure of cuticular hydrocarbon chain length) was lower in mosquitoes exposed to short photoperiod and low relative humidity, and increased with age. Individual cuticular hydrocarbon peaks were examined, and several cuticular hydrocarbons were identified as potential biomarkers of dry- and wet-season conditions, age, and insemination status. Conclusions Results from this study indicate that morphological and chemical changes underlie aestivation of Anopheles gambiae and may serve as biomarkers of aestivation.
Collapse
Affiliation(s)
| | | | | | | | | | - Gideon Wasserberg
- Department of Biology, University of North Carolina Greensboro, 235 Eberhart Bldg, Greensboro, NC 27402, USA.
| |
Collapse
|
29
|
Ecophysiology of Anopheles gambiae s.l.: persistence in the Sahel. INFECTION GENETICS AND EVOLUTION 2014; 28:648-61. [PMID: 24933461 DOI: 10.1016/j.meegid.2014.05.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/21/2014] [Accepted: 05/26/2014] [Indexed: 11/23/2022]
Abstract
The dry-season biology of malaria vectors is poorly understood, especially in arid environments when no surface waters are available for several months, such as during the dry season in the Sahel. Here we reappraise results on the dry-season physiology of members of the Anopheles gambiae s.l. complex in the broad context of dormancy in insects and especially in mosquitoes. We examine evidence on seasonal changes in reproduction, metabolism, stress tolerance, nutrition, molecular regulation, and environmental conditions and determine if the current results are compatible with dry-season diapause (aestivation) as the primary strategy for persistence throughout the dry season in the Sahel. In the process, we point out critical gaps in our knowledge that future studies can fill. We find compelling evidence that members of the An. gambiae s.l. complex undergo a form of aestivation during the Sahelian dry season by shifting energetic resources away from reproduction and towards increased longevity. Considering the differences between winter at temperate latitudes, which entails immobility of the insect and hence reliance on physiological solutions, as opposed to the Sahelian dry season, which restricts reproduction exclusively, we propose that behavioral changes play an important role in complementing physiological changes in this strategy.
Collapse
|
30
|
Mamai W, Mouline K, Blais C, Larvor V, Dabiré KR, Ouedraogo GA, Simard F, Renault D. Metabolomic and ecdysteroid variations in Anopheles gambiae s.l. mosquitoes exposed to the stressful conditions of the dry season in Burkina Faso, West Africa. Physiol Biochem Zool 2014; 87:486-97. [PMID: 24769712 DOI: 10.1086/675697] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This study explored the metabolic adjustments prompted by a switch between the rainy and dry season conditions in the African malaria mosquitoes Anopheles gambiae (M and S molecular forms) and Anopheles arabiensis. Mosquitoes were reared in contrasted experimental conditions reflecting environmental variation in Burkina Faso. Thirty-five metabolites (including sugars, polyols, and amino acids) were monitored in newly emerged males and females, and their ecdysteroid titers were determined. Metabolomic signatures were remarkably similar across species, when specimens of same age and sex were reared under identical experimental conditions. In males and females, amino acids (including glycine, leucine, phenylanine, serine, threonine, and valine) were accumulated in 1-h-old mosquitoes, then decreased 24 h after emergence, probably reflecting adult maturation and the amino acid-consuming process of cuticle sclerotisation. In turn, elevated amounts of alanine and proline in 24-h-old mosquitoes may assist the development of flight ability. Lower concentration of tricarboxylic acid cycle intermediates and isoleucine characterized older females reared under dry season conditions, suggesting metabolic and reproduction depression. In all cases, ecdysteroid concentration was much higher in males than in females, with significant seasonal variation in males. This might reflect a unique role of these hormones in shaping reproductive strategies and population demography in the An. gambiae s.l. species complex, further contributing to local adaptation in a highly fluctuating environment.
Collapse
Affiliation(s)
- W Mamai
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, 399 Avenue de la Liberté, 01 BP 545, Bobo-Dioulasso, Burkina Faso; 2Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche (UMR) IRD 224-Centre National de la Recherche Scientifique (CNRS) 5290-Université de Montpellier 1-Université de Montpellier 2 Maladies Infectieuses et Vecteurs Écologie, Génétique, Évolution et Contrôle, 911 Avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France; 3Université Polytechnique de Bobo-Dioulasso, Bobo-Dioulasso, Burkina Faso; 4Université Pierre et Marie Curie (UPMC), UMR Institut National de la Recherche Agronomique-UPMC 1272 PISC, 7 quai St Bernard, 75252 Paris Cedex 05, France; 5Université de Rennes 1, UMR CNRS 6553 Ecosystèmes, Biodiversité, Evolution, Campus de Beaulieu, 263 Avenue du Gal Leclerc, CS 74205 35042 Rennes Cedex, France
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Artis ML, Huestis DL, Lehmann T. The effects of oviposition-site deprivation on longevity and bloodfeeding rate in Anopheles gambiae. Parasit Vectors 2014; 7:163. [PMID: 24708656 PMCID: PMC3994212 DOI: 10.1186/1756-3305-7-163] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 03/15/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The African malaria mosquito, Anopheles gambiae, needs surface water in order to lay their eggs. In many parts of Africa, there are dry periods varying from days to months in length when suitable larval sites are not available and female mosquitoes experience oviposition-site deprivation (OSD). Previous studies have shown that egg-laying and egg-hatching rates were reduced due to OSD. Here, we assessed its effect on longevity and bloodfeeding rate of Anopheles gambiae. We predicted that OSD will increase mosquito longevity and the aptitude of mosquitoes to take additional blood meals; importantly, these changes will increase its vectorial capacity. METHODS To measure the effect of OSD, four treatments were utilized: two oviposition-deprived groups, one of which was bloodfed once (OBOD) and one that was bloodfed weekly (MBOD); a non-oviposition-deprived, weekly bloodfed control group (MBC); and a blood-deprived age-control group (BD). Mortality was assessed daily and bloodfeeding rate was measured at weekly intervals. RESULTS Under OSD, survival of female A. gambiae was reduced by 10-20%, reflecting reduction of the MBOD and OBOD groups from the MBC group, respectively. Likewise, bloodfeeding response during three weeks of OSD was reduced but the reduction varied as a function of time from the last blood meal. CONCLUSIONS These results indicate that OSD is expected to reduce A. gambiae vectorial capacity and that OSD alone does not act as cue used by female mosquitoes to switch into a dormant state of extended survivorship with reproductive quiescence.
Collapse
Affiliation(s)
- Monica L Artis
- Laboratory of Malaria and Vector Research, National Institutes of Health, Bethesda, MD, USA
| | - Diana L Huestis
- Laboratory of Malaria and Vector Research, National Institutes of Health, Bethesda, MD, USA
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
32
|
Abstract
Diapause, a dominant feature in the life history of many mosquito species, offers a mechanism for bridging unfavorable seasons in both temperate and tropical environments and serves to synchronize development within populations, thus directly affecting disease transmission cycles. The trait appears to have evolved independently numerous times within the Culicidae, as exemplified by the diverse developmental stages of diapause in closely related species. Its impact is pervasive, not only influencing the arrested stage, but also frequently altering physiological processes both before and after diapause. How the diapause response can be molded evolutionarily is critical for understanding potential range expansions of native and newly introduced species. The study of hormonal regulation of mosquito diapause has focused primarily on adult diapause, with little current information available on larval diapause or the intriguing maternal effects that regulate egg diapause. Recent quantitative trait locus, transcriptome, and RNA interference studies hold promise for interpreting the complex suite of genes that subserve the diapause phenotype.
Collapse
Affiliation(s)
- David L Denlinger
- Departments of Entomology and Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, Ohio 43210;
| | | |
Collapse
|
33
|
Lehmann T, Dao A, Yaro AS, Diallo M, Timbiné S, Huestis DL, Adamou A, Kassogué Y, Traoré AI. Seasonal variation in spatial distributions of Anopheles gambiae in a Sahelian village: evidence for aestivation. JOURNAL OF MEDICAL ENTOMOLOGY 2014; 51:27-38. [PMID: 24605449 PMCID: PMC3960504 DOI: 10.1603/me13094] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Changes in spatial distribution of mosquitoes over time in a Sahelian village were studied to understand the sources of the mosquitoes during the dry season when no larval sites are found. At that time, the sources of Anopheles gambiae Giles may be local shelters used by aestivating mosquitoes or migrants from distant populations. The mosquito distribution was more aggregated during the dry season, when few houses had densities 7- to 24-fold higher than expected. The high-density houses during the dry season differed from those of the wet season. Most high-density houses during the dry season changed between years, yet their vicinity was rather stable. Scan statistics confirmed the presence of one or two adjacent hotspots in the dry season, usually found on one edge of the village. These hotspots shifted between the early and late dry season. During the wet season, the hotspots were relatively stable near the main larval site. The locations of the hotspots in the wet season and early and late dry season were similar between years. Season-specific, stable, and focal hotspots are inconsistent with the predictions based on the arrival of migrants from distant localities during the dry season, but are consistent with the predictions based on local shelters used by aestivating mosquitoes. Targeting hotspots in Sahelian villages for vector control may not be effective because the degree of aggregation is moderate, the hotspots are not easily predicted, and they are not the sources of the population. However, targeting the dry-season shelters may be highly cost-effective, once they can be identified and predicted.
Collapse
Affiliation(s)
- Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD 208&52, USA.
| | - A Dao
- Mali International Center for Excellence in Research (ICER), University of Sciences, Techniques and Technologies, Bamako, Mali
| | - A S Yaro
- Mali International Center for Excellence in Research (ICER), University of Sciences, Techniques and Technologies, Bamako, Mali
| | - M Diallo
- Mali International Center for Excellence in Research (ICER), University of Sciences, Techniques and Technologies, Bamako, Mali
| | - S Timbiné
- Mali International Center for Excellence in Research (ICER), University of Sciences, Techniques and Technologies, Bamako, Mali
| | - D L Huestis
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD 208&52, USA
| | - A Adamou
- Mali International Center for Excellence in Research (ICER), University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Y Kassogué
- Mali International Center for Excellence in Research (ICER), University of Sciences, Techniques and Technologies, Bamako, Mali
| | - A I Traoré
- Mali International Center for Excellence in Research (ICER), University of Sciences, Techniques and Technologies, Bamako, Mali
| |
Collapse
|
34
|
Tene Fossog B, Antonio-Nkondjio C, Kengne P, Njiokou F, Besansky NJ, Costantini C. Physiological correlates of ecological divergence along an urbanization gradient: differential tolerance to ammonia among molecular forms of the malaria mosquito Anopheles gambiae. BMC Ecol 2013; 13:1. [PMID: 23294940 PMCID: PMC3548750 DOI: 10.1186/1472-6785-13-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 12/27/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Limitations in the ability of organisms to tolerate environmental stressors affect their fundamental ecological niche and constrain their distribution to specific habitats. Evolution of tolerance, therefore, can engender ecological niche dynamics. Forest populations of the afro-tropical malaria mosquito Anopheles gambiae have been shown to adapt to historically unsuitable larval habitats polluted with decaying organic matter that are found in densely populated urban agglomerates of Cameroon. This process has resulted in niche expansion from rural to urban environments that is associated with cryptic speciation and ecological divergence of two evolutionarily significant units within this taxon, the molecular forms M and S, among which reproductive isolation is significant but still incomplete. Habitat segregation between the two forms results in a mosaic distribution of clinally parapatric patches, with the M form predominating in the centre of urban agglomerates and the S form in the surrounding rural localities. We hypothesized that development of tolerance to nitrogenous pollutants derived from the decomposition of organic matter, among which ammonia is the most toxic to aquatic organisms, may affect this pattern of distribution and process of niche expansion by the M form. RESULTS Acute toxicity bioassays indicated that populations of the two molecular forms occurring at the extremes of an urbanization gradient in Yaounde, the capital of Cameroon, differed in their response to ammonia. The regression lines best describing the dose-mortality profile differed in the scale of the explanatory variable (ammonia concentration log-transformed for the S form and linear for the M form), and in slope (steeper for the S form and shallower for the M form). These features reflected differences in the frequency distribution of individual tolerance thresholds in the two populations as assessed by probit analysis, with the M form exhibiting a greater mean and variance compared to the S form. CONCLUSIONS In agreement with expectations based on the pattern of habitat partitioning and exposure to ammonia in larval habitats in Yaounde, the M form showed greater tolerance to ammonia compared to the S form. This trait may be part of the physiological machinery allowing forest populations of the M form to colonize polluted larval habitats, which is at the heart of its niche expansion in densely populated human settlements in Cameroon.
Collapse
Affiliation(s)
- Billy Tene Fossog
- Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche MIVEGEC (UM1, UM2, CNRS 5290, IRD 224), Montpellier, France
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
- Faculty of Sciences, University of Yaounde I, Yaounde, Cameroon
| | - Christophe Antonio-Nkondjio
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
| | - Pierre Kengne
- Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche MIVEGEC (UM1, UM2, CNRS 5290, IRD 224), Montpellier, France
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
| | - Flobert Njiokou
- Faculty of Sciences, University of Yaounde I, Yaounde, Cameroon
| | - Nora J Besansky
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Carlo Costantini
- Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche MIVEGEC (UM1, UM2, CNRS 5290, IRD 224), Montpellier, France
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
| |
Collapse
|
35
|
Dieter KL, Huestis DL, Lehmann T. The effects of oviposition-site deprivation on Anopheles gambiae reproduction. Parasit Vectors 2012; 5:235. [PMID: 23072301 PMCID: PMC3514158 DOI: 10.1186/1756-3305-5-235] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 09/23/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The African malaria mosquito, Anopheles gambiae, depends on availability of suitable surface water for oviposition. Short and long dry spells occur throughout the year in many parts of its range that limit its access to oviposition sites. Although not well understood, oviposition-site deprivation has been found to rapidly reduce egg batch size and hatch rate of several mosquito species. We conducted laboratory experiments to assess these effects of oviposition-site deprivation on An. gambiae and to evaluate the role of nutrition and sperm viability as mediators of these effects. METHODS Anopheles gambiae adults (1-2 d old) from the G3 laboratory colony were assigned to the following treatment groups: oviposition-deprived (fed once and then deprived of oviposition site for 7 or 14 d), multiple-fed control (fed regularly once a week and allowed to lay eggs without delay), and age matched blood-deprived control (fed once, three days before water for oviposition was provided). Egg batch size and hatch rate were measured. In the second experiment two additional treatment groups were included: oviposition-deprived females that received either a second (supplemental) blood meal or virgin males (supplemental mating) 4 days prior to receiving water for oviposition. RESULTS An. gambiae was highly sensitive to oviposition-site deprivation. Egg batch size dropped sharply to 0-3.5 egg/female within 14 days, due to reduced oviposition rate rather than a reduced number of eggs/batch. Egg hatch rate also fell dramatically to 0-2% within 7 days. The frequency of brown eggs that fail to tan was elevated. A supplemental blood meal, but not 'supplemental insemination,' recovered the oviposition rate of females subjected to oviposition-site deprivation. Similarly, a supplemental blood meal, but not 'supplemental insemination,' partly recovered hatch rate, but this increase was marginally significant (P < 0.069). CONCLUSIONS Even a short dry spell resulting in oviposition-site deprivation for several days may result in a dramatic decline of An. gambiae populations via reduced fecundity and fertility. However, females taking supplemental blood meals regain at least some reproductive success. If mosquitoes subjected to oviposition-site deprivation increase the frequency of blood feeding, malaria transmission may even increase during a short dry spell. The relevance of oviposition-site deprivation as a cue to alter the physiology of An. gambiae during the long dry season is not evident from these results because no reduction in hatch rate was evident in wild M-form An. gambiae collected in the dry season in the Sahel by previous studies.
Collapse
Affiliation(s)
- Kathryne L Dieter
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Room 2W-09-C, Rockville, MD 20852, USA
| | | | | |
Collapse
|
36
|
Yaro AS, Traoré AI, Huestis DL, Adamou A, Timbiné S, Kassogué Y, Diallo M, Dao A, Traoré SF, Lehmann T. Dry season reproductive depression of Anopheles gambiae in the Sahel. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:1050-1059. [PMID: 22609421 PMCID: PMC4789105 DOI: 10.1016/j.jinsphys.2012.04.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/26/2012] [Accepted: 04/02/2012] [Indexed: 05/30/2023]
Abstract
The African malaria mosquito, Anopheles gambiae, is widespread south of the Sahara including in dry savannahs and semi-arid environments where no surface water exists for several months a year. Adults of the M form of An. gambiae persist through the long dry season, when no surface waters are available, by increasing their maximal survival from 4 weeks to 7 months. Dry season diapause (aestivation) presumably underlies this extended survival. Diapause in adult insects is intrinsically linked to depressed reproduction. To determine if reproduction of the Sahelian M form is depressed during the dry season, we assessed seasonal changes in oviposition, egg batch size, and egg development, as well as insemination rate and blood feeding in wild caught mosquitoes. Results from xeric Sahelian and riparian populations were compared. Oviposition response in the Sahelian M form dropped from 70% during the wet season to 20% during the dry season while the mean egg batch size among those that laid eggs fell from 173 to 101. Correspondingly, the fraction of females that exhibited gonotrophic dissociation increased over the dry season from 5% to 45%, while a similar fraction of the population retained developed eggs despite having access to water. This depression in reproduction the Sahelian M form was not caused by a reduced insemination rate. Seasonal variation in these reproductive parameters of the riparian M form population was less extreme and the duration of reproductive depression was shorter. Blood feeding responses did not change with the season in either population. Depressed reproduction during the dry season in the Sahelian M form of An. gambiae provides additional evidence for aestivation and illuminates the physiological processes involved. The differences between the Sahelian and riparian population suggest an adaptive cline in aestivation phenotypes between populations only 130 km apart.
Collapse
Affiliation(s)
- Alpha S Yaro
- Malaria Research and Training Center/Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali.
| | | | | | | | | | | | | | | | | | | |
Collapse
|