Malaria causes over one million deaths annually. A promising control strategy relies on targeting mosquito populations when they are vulnerable such as during the dry season. Prolonged dry season during which larval sites are scarce and mosquito populations decline prevail in the Sahel which covers a large part ofMali. How mosquitoes withstand the dry season remains unknown. Some evidence supports the adult estivation hypothesis whereby mosquitoes remain inprotected sites, except for sporadic journeys to obtain blood-meals to sustain themselves rather than to produce eggs. Alternatively, mosquitoes do not survive the dry season locally; rather, they migrate from areas where reproduction continues at permanent water bodies. We aim to determine if An.
Gambiae estivate during the dry season in the Sahel; and if so, identify their hidden resting sites. As mosquito populations decline, standard sampling techniques yield zero mosquitoes. Because estivating females take blood meals intermittently, the most promising sampling technique is by human landing catch (HLC). Finding a few mosquitoes during the dry season have been reported, but it could not be determined if they were estivating or were migrants from villages, where larval sites persist. This study can resolve this because we captured marked and released over 5000 mosquitoes just before the dry season (November 2008). We aim to collect mosquitoes during the end of the dry season (April 2009) and the onset of the rainy season (June 2009) and find out if they bear marks from the previous wet season. Finding a single marked specimen will be the ultimate proof for the estivation hypothesis.
Experiments will take place in the Sahelian village Thierola, Koulikoro Region, Mali, where the dry season exceeds 7 months. The village was chosen because it has no permanent larval sites and is a small community (< 300 inhabitants) living in 90 houses, allowing collection in all houses in a single day. Thirty adult male residing in Thierola will be recruited as collectors for the HLC. A collector will expose his lower legs to attract mosquitoes. Using a mouth aspirator, mosquitoes will be collected as they land on the collector's legs, ideally, before a blood meal is taken. Collection will be conducted 6pm to 6am for 14 consecutive days in April 2009 and again after the rains begin in June 2009. Collectors will be informed of the proper collecting procedures during the consenting procedure. During the time of year we propose to conduct this work, mosquito populations will be at their minima and any surviving mosquitoes will take blood meals infrequently. Therefore, the HLCs will be conducted when malaria transmission is extremely low and the risk to volunteers essentially nil. In summary, knowledge of how mosquitoes survive the dry season would open novel ways for vector and malaria control.
| Estimated Enrollment: |
60 |
| Study Start Date: |
March 2009 |
Malaria causes over one million deaths annually. A promising control strategy relies on targeting mosquito populations when they are vulnerable such as during the dry season. Prolonged dry season during which larval sites are scarce and mosquito populations decline prevail in the Sahel which covers a large part ofMali. How mosquitoes withstand the dry season remains unknown. Some evidence supports the adult estivation hypothesis whereby mosquitoes remain inprotected sites, except for sporadic journeys to obtain blood-meals to sustain themselves rather than to produce eggs. Alternatively, mosquitoes do not survive the dry season locally; rather, they migrate from areas where reproduction continues at permanent water bodies. We aim to determine if An.
Gambiae estivate during the dry season in the Sahel; and if so, identify their hidden resting sites. As mosquito populations decline, standard sampling techniques yield zero mosquitoes. Because estivating females take blood meals intermittently, the most promising sampling technique is by human landing catch (HLC). Finding a few mosquitoes during the dry season have been reported, but it could not be determined if they were estivating or were migrants from villages, where larval sites persist. This study can resolve this because we captured marked and released over 5000 mosquitoes just before the dry season (November 2008). We aim to collect mosquitoes during the end of the dry season (April 2009) and the onset of the rainy season (June 2009) and find out if they bear marks from the previous wet season. Finding a single marked specimen will be the ultimate proof for the estivation hypothesis.
Experiments will take place in the Sahelian village Thierola, Koulikoro Region, Mali, where the dry season exceeds 7 months. The village was chosen because it has no permanent larval sites and is a small community (< 300 inhabitants) living in 90 houses, allowing collection in all houses in a single day. Thirty adult male residing in Thierola will be recruited as collectors for the HLC. A collector will expose his lower legs to attract mosquitoes. Using a mouth aspirator, mosquitoes will be collected as they land on the collector's legs, ideally, before a blood meal is taken. Collection will be conducted 6pm to 6am for 14 consecutive days in April 2009 and again after the rains begin in June 2009. Collectors will be informed of the proper collecting procedures during the consenting procedure. During the time of year we propose to conduct this work, mosquito populations will be at their minima and any surviving mosquitoes will take blood meals infrequently. Therefore, the HLCs will be conducted when malaria transmission is extremely low and the risk to volunteers essentially nil. In summary, knowledge of how mosquitoes survive the dry season would open novel ways for vector and malaria control.
Purpose
