*2.1. Study Site*

From April to May 2012, *An. gambiae* s.l. mosquitoes were collected in houses in two villages: Kyamyorwa (02◦0427.5 S, 31◦3410.8 E) and Kiteme (02◦0320.9 S, 31◦2716.8 E) in Muleba, a rural district on the western shore of Lake Victoria in northwest Tanzania (Figure 1).

**Figure 1.** Map showing mosquito collection site in north-western Tanzania.

The mosquito collection for this study was part of an ongoing large cluster randomized trial in Muleba district, north-western Tanzania [46]. *An. gambiae* s.s. were the main vectors found in this area and have historically exhibited high resistance levels to pyrethroids [28], with mortality after exposure not exceeding 35%. The L1014S point mutation associated with pyrethroid resistance was nearly fixed, while no *Ace*-1 mutation was found [37].
