PARIS - Researchers said on Wednesday they had discovered four natural mosquito repellents to succeed DEET, a compound whose origins go back to World War II.
DEET, or N,N-Diethyl- meta-toluamide, was introduced by the US Army in 1946 after troops deployed in the Pacific theatre fell sick from malaria and other mosquito-borne diseases.
It remains the primary insect repellent in use today, but it has to be applied fre- quently and is expensive. It also dissolves plastic, synthetic fabrics and painted surfaces.
More worryingly, there is evidence that flies and mosquitoes are developing resistance to it, and that the chemical disrupts an important enzyme in the mammalian nervous system.
In experiments that combined entomology and data-crunching computing, scientists at the University of California at Riverside uncovered the four alter- natives that may send DEET into retirement after 67 years.
"The candidates contain chemicals that do not dissolve plastic, are affordable and smell mildly like grapes, with three considered safe in human foods," says the study published on Wednesday in the journal Nature.
Out of the four, three have already been approved as food flavours or fragrances by the US Food and Drug Administration.
"Our findings could lead to a new generation of cheap, affordable repellents that could protect humans, animals and, in the future, our crops," said Dr Ananda-sankar Ray, an associate professor of entomology.