Biological fitness costs associated with the various permethrin resistance development statuses in Anopheles gambiae in Nigeria

Man, in a desperate bid to manage malaria-vectors, i.e., Anopheles gambiae s.l. (Diptera: Culicidae) has relentlessly relied on pyrethroid insecticides especially permethrin. Unfortunately, these mosquitoes have improved their survival with respect to this tactic which must have been associated with some fitness-costs. This study, therefore, evaluates the biological fitness-costs associated with permethrin-resistance development in An. gambiae s.l. in Kwara State, Nigeria. Susceptibility statuses of adult female An. gambiae s.l. populations collected from Oke-odo, Pipeline and Airport were established using World Health Organization Protocol. They were subsequently raised over three-generations and the fecundity, hatchability, development time for larvae, pupae and adult, adult emergence, the adult sex ratio was observed, noted, monitored and analysed using ANOVA (P<0.05). Permethrin-resistant, moderately-resistant and susceptible status were each observed in the An. gambiae s.l. populations of Oke-odo, pipeline and Airport, respectively. The biological fitness-costs showed that permethrin-resistant An. gambiae s.l. had reduced fecundity (F1=86.07%, F2=84.55% and F3=100%) and hatchability (F1=96.58%, F2=92.02% and F3=100%). Also, there were reduced larvae developmental-time (F1=35.71% and F2=42.86%), adult-emergence (F1=97.69%) and longevity (F1=46.39%) when compared with the susceptible population. Permethrin-resistance development in An. gambiae s.l. definitely comes with some biological fitness-costs that disadvantage its transmission potential and can be leveraged upon in vector-management.