Relative abundances of An. gambiae s.s. and An. arabiensis females in 1999, 2008 and 2010. White and black pies are proportions of An. gambiae s.s and An. arabiensis, respectively. Left, middle and right pie graphs are results of 1999, 2008 and 2010, respectively. A number below each pie graph is the number of collected larvae, and a number in parentheses is the number of habitats. Stars show a level of significance (* < 0.05, ** < 0.01, *** < 0.001). A dotted line shows the border of two geographical regions.