They say more research is needed to find alternatives to Deet, which was first developed by the US military.
Deet - or N,N-diethyl-meta-toluamide - is one of the most widely used active ingredients in insect repellents. It was developed by the US military, following its experience of jungle warfare during World War II.
The research was carried out on Aedes aegypti, a species of mosquito that spreads dengue and yellow fever. [The anopheles mosquito is the primary carrier of the malaria parasite.]One of the interesting things about recent research has been the discovery of how DEET really works. The mosquitos don't like it's smell. Who knew! Unfortunately, it seems as though they are able to get past their initial repulsion to the smell, so the effect of DEET may be more limited than it used to be. This is not good news, of course.