Using cattle to autodessiminate insect growth regulator, Pyriproxyfen to mosquitoes breeding habitats by Anopheles arabiensis

Using cattle to autodessiminate insect growth regulator, Pyriproxyfen to mosquitoes breeding habitats by Anopheles arabiensis Dickson Lwetoijera1, 2, Caroline Harris1, 2, Stefan Dongus1, 2, Gregor Devine 1, 2, Phillip McCall2 and Silas Majambere1, 2. 1 Ifakara Health Institute, P.O.Box 53, Ifakara, Tanzania 2 Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK Abstract Larviciding could complement other malaria control programs that target adult mosquitoes. However, locating all mosquito breeding habitats and the high implementation cost related to this remain major challenges for this strategy. The autodissemination of larvicides by mosquitoes offer a new possibility for larviciding. Therefore, this study aims at assessing the possibility to contaminate Anopheles arabiensis while they feed on cattle treated with pyriproxyfen (PPF) and their potential to transfer PPF into their breeding habitats. The study was carried out in rural Tanzania. Two screen houses (SFS) were built and inside each a mud hut was built where a cow was introduced. Unfed adult female An. arabiensis were released inside the SFS to feed on the cows. Clay pots were provided as resting sites for blood fed mosquitoes. In the control SFS, a cow was brushed with corn oil only whereas in the treated SFS it was brushed with corn oil and treated with pulverized PPF (Sumilarv 10%). Temporary breeding habitats for mosquitoes were installed inside the SFS. Eggs and larval presence and emergence inhibition were monitored daily from two days after mosquito release. Approximately all released mosquitoes blood-fed successfully in both control and treatment. Majority of mosquitoes were found resting inside the clay pots, walls and roof of cattle shed indicating that these resting sites can be used to contaminate mosquitoes. Significant adult emergence inhibition was demonstrated in larval bioassays with treated SFS mosquitoes, proving that mosquito were able to pick up PPF. The study is ongoing, assessing whether the contaminated mosquitoes can retain and transfer sufficient dose of PPF to their breeding habitats and inhibit mosquito emergence. Successful autodissemination of PPF and significant adult emergence inhibition in the contaminated breeding habitats will confirm demonstrate the efficacy of this technique for controlling malaria vectors.