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Presidential Green Chemistry Challenge: 2010 Designing Greener Chemicals Award



NatularTM Larvicide: Adapting Spinosad for Next-Generation Mosquito Control


Innovation and Benefits: Spinosad is an environmentally safe pesticide but is not stable in water and so therefore cannot be used to control mosquito larvae. Clarke has developed a way to encapsulate spinosad in a plaster matrix, allowing it to be released slowly in water and provide effective control of mosquito larvae. This pesticide, NatularTM, replaces organophosphates and other traditional, toxic pesticides and is approved for use in certified organic farming.

Summary of Technology: Spinosad, a 1999 Presidential Green Chemistry Challenge Award winner, is an effective insecticide with excellent control in many terrestrial applications. Its instability in water, however, renders it ineffective for extended application in aquatic environments.

Clarke has created a "sequential" plaster matrix that protects the spinosad molecule from water and releases it slowly, allowing extended performance of spinosad formulations for up to 180 days. This matrix is insoluble calcium sulfate hemihydrate plaster and water-soluble polyethylene glycol (PEG) binders fine-tuned for varying durations of insecticide release. The PEG dissolves slowly, exposing the spinosad and calcium sulfate to water. The calcium sulfate takes up the water to form the mineral gypsum and releases spinosad. Clarke formulated the plaster matrix for NatularTM larvicide entirely with approved pesticide inerts that also meet the U.S. Department of Agriculture's (USDA's) National Organics Standard (NOS). The resulting formulations of NatularTM larvicide provide excellent control of mosquito larvae in a range of aquatic environments from catch basins to salt marshes. Clarke manufactures the dustless, extended-release tablets with a solventless process that increases the environmental benefits.

NatularTM larvicide is effective at application rates 2–10-fold lower than traditional synthetic larvicides. It is 15-fold less toxic than the organophosphate alternative, does not persist in the environment, and is not toxic to wildlife. Its manufacture eliminates hazardous materials and processes. NatularTM is the first new, chemical larvicide for mosquito control in decades; it meets the highest standards for environmental stewardship and offers a new choice for Integrated Pest Management (IPM). It is especially useful in environments with intermittent water, such as tidal pools and flood plains. These intermittently wet areas provide excellent, short-term pools for mosquito breeding; the transient nature of the pooling makes traditional mosquito control difficult. The NatularTM larvicide can be applied in dry or wet conditions, however, and only releases the active ingredient when water is present.

The benefits of using Clarke's new formulations extend beyond the reduced environmental impact. Traditional larvicides require up to three applications per season. In contrast, NatularTM tablets require just one or two applications.

Altogether, NatularTM larvicide demonstrates green chemistry innovation through the development and design of its controlled-release matrix. With the projected adoption of NatularTM larvicide by local and federal agencies, Clarke anticipates a shift in the mosquito-borne disease management industry toward reduced overall synthetic load in the environment and improved health and quality of life in treated areas. In 2009, Clarke began commercial-scale production of NatularTM larvicide in the United States. This patent-pending formulation has been accepted for use domestically and abroad. Clarke also expects its slow-release matrix will enable controlled release of other active ingredients, including herbicides and veterinary drugs.

Podcast on the technology:

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