The use of challenge funds to promote economic and social development continues to grow, but has been the subject of relatively little research. This paper develops a definition of what challenge funds are and how they differ from other development funding mechanisms, taking into account their...

Of some 2,800 compounds screened for repellency against Aedes aegypti mosquitoes, 592 were initially effective. 164 were equal to the dimethyl phthalate standard, 33 were as good as the deet. The protection time and minimum effective dosage (MED) of each compound are given.