Insecticide bioassay results for Anopheles gambiae s.l . from 2008/2009 in two rounds of monitoring in four sentinel sites in Chad. Panel A shows percentage mortality 24 hours after a 1-hour exposure to the WHO diagnostic doses of insecticide. The minimum sample size for these assays was 100 and all individuals were non-blood fed females, 3-5 days post emergence. Panels B and C show the species distribution in each of the study sites during collection round one (Panel B) and round 2 (Panel C). The mosquitoes were morphologically identified as belonging to the Anopheles gambiae complex and then identified to species and molecular form by PCR. Anopheles arabiensis is shown in blue, An. gambiae S form in red, An. gambiae M form in yellow and An. gambiae M/S hybrids in green.