Slashdot Mirror
Monochromatic Light As a Species-selective Insecticide
An anonymous reader writes: The harmful effects of ultraviolet light have been long known. But now researchers at Tohoku University in Japan claim that visible blue light is also lethal to many insects, possibly even more so than UV, even at reasonable daylight intensities. Moreover, they report that certain species are more sensitive to specific wavelengths: Given the same intensity (3x10^18 photons/sec/m^2), light in the 440-467nm range was far more lethal to fruit flies than light of longer or shorter wavelengths. The wavelength 417nm was three times as effective at killing mosquito larvae than the shorter 404nm light, contradicting the notion that higher-energy photons always cause more damage. The research has wide implications for modeling the effect of natural and manmade environmental changes on insect populations and for selectively controlling populations of certain species.
That's surprisingly little energy. Blue light is that band about 2,7 eV per electron, so 2,7 * 3e18 = 8,1e18 eV/s/m^2 = 1.3 W/m^2. If you wanted to generate that much via a LED bulb with an external quantum efficiency of 20% then it'd take only 6,5 watts.
Is it really possible that a little 6,5W blue LED bulb could kill all the fruit flies in a square meter box - are insects really that sensitive to light? That would be amazing. Greenhouses that use supplimental lighting could fine-tune their frequencies to kill off particular pests pretty darn easily. A grower with heavy LED light supplimenting uses a couple hundred watts of LED per square meter. I mean, at those levels the right frequencies should be killing bugs on the *undersides* of leaves....
"We consider that six courts and an asylum claim are a rather odd way of returning to Sweden within a month."