Potential use of pyriproxyfen for control of mosquito-borne diseases: (1) Reduction in vectorial capacity of adult mosquitoes

Because the pyrethroid-resistance in mosquito vectors spread in the world, alternative chemicals are needed to better control mosquito-borne diseases such as malaria and dengue. Pyriproxyfen (PPF) is a juvenile hormone analog (JHA) and has been used against a range of insect pests including mosquitoes. We tested the effect of PPF treated bed nets against adult mosquitoes in the laboratory. Adult females of Anopheles gambiae s.s. and Aedes aegypti were exposed to polyethylene bed net treated with various concentration of alcohol solutions of PPF (0.1% - 0.001%w/v). After 3 minutes exposure to the net, mosquito fecundity, egg hatchability, blood feeding rate and adult longevity were evaluated. As a result, completely sterilizing activity was confirmed in An. gambiae exposed to 0.01% (less than 10 mg A.I. / m²) and 0.1% (35 mg A.I. / m²) treated net. Fecundity of exposed Ae. aegypti was reduced at 0.1% treated net, and egg hatchability was also significantly suppressed with increasing PPF dose. In both An. gambiae and Ae. aegypti, a single exposure to 0.1% treated net, blood feeding rates were significantly reduced compared to control for their entire lifetime. Longevities in both species were also significantly shortened in the PPF exposed females. All such effects, i.e. deteriorated fecundity, egg hatchability, blood feeding rate and longevity, cause dramatic reduction in the “vectrial capacity” of the mosquito populations. Therefore it could be concluded that PPF has a great potential for the pyrethroid-resistant management in control of mosquito-borne diseases.