November 14, 2016

Wind-assisted long-distance migration of malaria mosquitoes in the Sahel

Written by Tovi Lehmann, Diana Huestis, Alpha Yaro, Jenna Florio, Moussa Diallo, Zana Sanogo, Samake Djibril, Roy Faiman, Jason W. Chapman, Donald R. Reynolds, Laura E. Burgin, Adama Dao

This post originally appeared in ASTMH.

Over the past decade, malaria control efforts have greatly reduced its burden even in its home base – Africa, raising hopes for malaria eradication in some reader’s lifetime. Malaria transmission in Africa extends from the Equatorial Zone to the Sahel where it is confined to the short rainy season. Persistence of anopheline vectors in areas without surface waters for 3-8 months a year attests for the sophisticated strategies employed by the vectors. Recent evidence suggests that Anopheles coluzzii persists locally throughout the dry season by a form of diapause (aestivation), whereas A. gambiae and A. arabiensis rely on long-distance migration from areas where reproduction continues year round. This contradicts the widely accepted view that these vectors do not disperse beyond a few kilometers in a lifetime. Here, we summarize aerial sampling of insects 100-300 m above ground conducted between May 2012 and November 2015 in four Sahelian villages. A total of 30 A. gambiae s.l. and 117 A. pharoensis were captured among >3,000 mosquitoes and over half a million other insects during 747 aerial night collections. No mosquitoes were captured in 502 control captures raised briefly to 120 m during launches and retrievals, corroborating that these species were intercepted at high altitudes rather than near the ground. A high proportion of the mosquitoes were gravid, indicating that they might carry human pathogens. Because such movements of mosquito vectors are regular and involve many thousands of mosquitoes per night, they have important implications for disease emergence and reemergence as well as for disease elimination programs. A comprehensive analysis of these data will be presented.

 

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