2008 Designing Greener Chemicals Award
Dow AgroSciences LLC
Spinetoram: Enhancing a Natural Product for Insect Control
Innovation and Benefits: Spinosad biopesticide from Dow AgroSciences controls many insect pests on vegetables, but is not particularly effective against certain key pests of tree fruits. To solve this problem, Dow AgroSciences used an "artificial neural network" to identify analogous molecules that might be more effective against fruit-tree pests. They then developed a green chemical synthesis for the new insecticide, called spinetoram. Spinetoram retains the favorable environmental benefits of spinosad while replacing organophosphate pesticides for tree fruits, tree nuts, small fruits, and vegetables.
Spinosad biopesticide won the Presidential Green Chemistry Challenge Award for Designing Greener Chemicals in 1999. Spinosad, a combination of spinosyns A and D, is effective against insect pests on vegetables, but there have been few green chemistry alternatives for insect-pest control in tree fruits and tree nuts. Dow AgroSciences has now developed spinetoram, a significant advancement over spinosad that extends the success of spinosad to new crops.
The discovery of spinetoram involved the novel application of an artificial neural network (ANN) to the molecular design of insecticides. Dow AgroSciences researchers used an ANN to understand the quantitative structure-activity relationships of spinosyns and to predict analogues that would be more active. The result is spinetoram, a mixture of 3'-O-ethyl-5,6-dihydro spinosyn J and 3'-O-ethyl spinosyn L. Dow AgroSciences makes spinetoram from naturally occurring fermentation products spinosyns J and L by modifying them with a low-impact synthesis in which catalysts and most reagents and solvents are recycled. The biology and chemistry of spinetoram have been extensively researched; the results have been published in peer-reviewed scientific journals and presented at scientific meetings globally.
Spinetoram provides significant and immediate benefits to human health and the environment over existing insecticides. Azinphos-methyl and phosmet, two organophosphate insecticides, are widely used in pome fruits (such as apples and pears), stone fruits (such as cherries and peaches), and tree nuts (such as walnuts and pecans). The mammalian acute oral toxicity of spinetoram is more than 1,000 times lower than that of azinphos-methyl and 44 times lower than that of phosmet. The low toxicity of spinetoram reduces the risk of exposures throughout the supply chain: in manufacturing, transportation, and application and to the public.
Spinetoram has a lower environmental impact than do many current insecticides because both its use rate and its toxicity to non-target species are low. Spinetoram is effective at much lower rates than many competing insecticides. It is effective at use rates that are 10-34 times lower than azinphos-methyl and phosmet. Spinetoram is also less persistent in the environment compared with other traditional insecticides. In the United States alone, Dow AgroSciences expects spinetoram to eliminate about 1.8 million pounds of organophosphate insecticides applied to pome fruit, stone fruit, and tree nuts during its first five years of use. In 2007, U.S. EPA granted pesticide registrations to the spinetoram products RadiantT and DelegateT and Dow AgroSciences began commercial sales.
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