Recovery of females exposed to permethrin at temperatures lower than 26°C. Hatched bars reflect survival 24 hours after exposure to permethrin at A) 12, 18 or 22°C in exposure temperature experiments or B) 18°C in acclimation experiments, using scoring criteria described by the WHO resistance-monitoring assay. Solid bars show the proportion of females surviving by this same measure after those groups experienced 15 minutes at 26°C. The recovery of these females suggests that post-exposure temperature can influence insecticide susceptibility. The dashed line at 0.02 indicates the level of survival above which populations are classified as ‘resistant’ by the WHO.