Researchers Rediscover Fast-Acting German Insecticide Lost in the Aftermath of WWII
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Researchers rediscover fast-acting German insecticide lost in the aftermath of WWII
A new study in the Journal of the American Chemical Society explores the chemistry as well as the complicated and alarming history of DFDT, a fast-acting insecticide.
"We set out to study the growth of crystals in a little-known insecticide and uncovered its surprising history, including the impact of World War II on the choice of DDT-and not DFDT-as a primary insecticide in the 20th century," said Bart Kahr, professor of chemistry at New York University and one of the study's senior authors.
Kahr and fellow NYU chemistry professor Michael Ward study the growth of crystals, which two years ago led them to discover a new crystal form of the notorious insecticide DDT. DDT is known for its detrimental effect on the environment and wildlife. But the new form developed by Kahr and Ward was found to be more effective against insects-and in smaller amounts, potentially minimizing its environmental impact.
In continuing to explore the crystal structure of insecticides, the research team began studying fluorinated forms of DDT, swapping out chlorine atoms for fluorine. They prepared two solid forms of the compound-a monofluoro and a difluoro analog-and tested them on fruit flies and mosquitoes, including mosquito species that carry malaria, yellow fever, Dengue, and Zika. The solid forms of fluorinated DDT killed insects more quickly than did DDT; the difluoro analog, known as DFDT, killed mosquitoes two to four times faster.
"Speed thwarts the development of resistance," said Ward, a senior author on the study. "Insecticide crystals kill mosquitoes when they are absorbed through the pads of their feet. Effective compounds kill insects quickly, possibly before they are able to reproduce."
The researchers also made a detailed analysis of the relative activities of the solid-state forms of fluorinated DDT, noting that less thermodynamically stable forms-in which the crystals liberate molecules more easily-were more effective at quickly killing insects.
[...] "We were surprised to discover that at the outset DDT had a competitor which lost the race because of geopolitical and economic circumstances, not to mention its connection to the German military, and not necessarily because of scientific considerations. A faster, less persistent insecticide, as is DFDT, might have changed the course of the 20th century; it forces us to imagine counterfactual science histories," said Kahr.
More information: Xiaolong Zhu et al, Manipulating Solid Forms of Contact Insecticides for Infectious Disease Prevention, Journal of the American Chemical Society (2019). DOI: 10.1021/jacs.9b08125
Journal information: Journal of the American Chemical Society Provided by New York University
Citation: Researchers rediscover fast-acting German insecticide lost in the aftermath of WWII (2019, October 11) retrieved 13 October 2019 from https://phys.org/news/2019-10-rediscover-fast-acting-german-insecticide-lost.html
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