Dose–response curves for An. arabiensis exposed to lambda-cyhalothrin on Zanzibar. An. gambiae were exposed to a range of concentrations of lambda-cyhalothrin in WHO susceptibility tests. The lethal concentration for 50% mortality (LC50) was calculated by fitting a generalised linear model (GLM) using a binomial logit-link function. The LC50 is shown above each plot. For Tumbe, two additional curves are shown specific for An. arabiensis (red dashed) and An. merus (orange dashed).