Resistance of malaria vectors to insecticides in BURKINA FASO

The resistance of malaria vectors to insecticides attributed to their use in agriculture is not well elucidated. In order to test this hypothesis, the sensitivity of An. gambiae s.l. to DDT and pyrethroids was evaluated in 2006 in four cotton and vegetable growing areas (Saaba, Nongremasson, Zampa and Boromo). Sensitivity was tested on farmed females. Mortality ranged from 56 to 92% for DDT, 98 to 100% for permethrin and 100% for deltamethrin. The longest KDT50 and KDT95 were 47.52 and 105.69 min for DDT; 13.33 and 38.34 min for permethrin and 7.32 and 14.82 min for deltamethrin, respectively. For An. arabiensis the Kdr frequency was 0.13 and for the M molecular form of An. gambiae s.s. it was 0.69 compared to 0.18 in the S molecular form. The highest frequency of the Kdr gene was found in Zampa and the lowest in Boromo. Within the An. gambiae complex, the Kdr gene was more frequent in An. gambiae s.s. In summary, resistance to DDT was present at all cotton and vegetable growing sites and was being established for pyrethroids.