Relative mRNA levels of candidate resistance genes measured by qPCR. The level of expression was measured from An. coluzzi from Vallée du Kou (2011, 2012, and 2013) and Tengrela (2012 and 2013) in samples independent to those used in the microarray experiments and not exposed to insecticide. The relative values are presented according to the ddCt method  ± SEM of six biological replicates. A two-tailed Student’s t-test was performed between the yearly values within population (log-scale). *= p < 0.05; n.s. = not significant.