Pyriproxyfen-treated bed nets reduce reproductive fitness and longevity of pyrethroid-resistant Anopheles gambiae under laboratory and field conditions

Abstract Background The efficacy of insecticide-treated nets (ITNs) containing the insect growth regulator pyriproxyfen (PPF) and pyrethroid insecticides (PPF-ITNs) is being assessed in clinical trials to determine whether they provide greater protection from malaria than standard pyrethroid-treated ITNs areas where mosquitoes are resistant pyrethroids. Understanding entomological mode action this new ITN class will aide interpretation results these trials. Methods Anopheles gambiae sensu lato ( s.l .) a susceptible laboratory strain were exposed PPF-treated netting 24 h, 6 immediately prior to, or h post blood feeding, impact on fecundity, fertility longevity recorded. Pyrethroid-resistant populations permethrin PPF cone bioassays daily mortality Mosquitoes also collected inside houses pre- post-distribution PPF-ITNs trial conduced Burkina Faso; female An. s.l. then for fecundity fertility. Results exposure reduced median adult lifespan insecticide-susceptible by 4 5 days all times (p < 0.05) other pre-blood meal resulted almost complete lifelong sterilization. pyrethroid-resistant was at least after compared untreated nets, but unaffected only ITNs. A total 386 blood-fed gravid . females five villages between 1 12 months before distribution PPF-ITNs. Of mosquitoes, 75% laid eggs remaining 25% appeared have normal ovaries upon dissection. In contrast, 8.6% 631 PPF-ITN successfully oviposited; 276 (43.7%) did not oviposit had apparently dissection, 301 (47.7%) abnormal Egg numbers significantly lower (average 138/female vs 85 distribution, p 0.05). Conclusion Exposure mixture pyrethroids shortens reduces reproductive output. Sterilization vectors lasted one year under operational conditions. These findings suggest longer effective PPF-pyrethroid reported previously.