"We are exploring the potential use of natural pesticides based on plant essential oils — commonly used in foods and beverages as flavorings," said Murray Isman, Ph.D., of the University of British Columbia. These new pesticides are generally a mixture of tiny amounts of two to four different spices diluted in water. Some of these essential oils are lethal to insects, while others act as repellents.
With funding from the botanical pesticide company EcoSMART®, Alpharetta, Ga., Isman and colleagues have tested numerous plant essential oils and have found the substances possess a broad range of insecticidal activity. Other scientists are currently exploring the insect-fighting potential of lavender, basil, bergamot, patchouli oil, and at least a dozen other oils from exotic plant sources in China. Some spiced-based commercial products now being used by farmers have already shown success in protecting organic strawberry, spinach, and tomato crops against destructive aphids and mites, the researcher says.
Certain pluses exist for these "killer spices." Unlike conventional pesticides, the essential oil pesticides do not require extensive regulatory approval. They're also safer for farm workers, who are at high risk for pesticide exposure.
But the spicy pesticides are not a panacea. They tend to evaporate and degrade rapidly in sunlight, forcing farmers to make more frequent crop applications compared to conventional pesticides. The potential increases in labor and energy inputs could be significant. The effectiveness of some "killer spices" lasts only a few hours, compared to days or even months for conventional pesticides. Isman noted researchers are now seeking ways of making the natural pesticides longer-lasting and more potent.
"Conventional pesticides are still the most effective way to control caterpillars, grasshoppers, beetles and other large insects on commercial food crops," Isman said. "But at the end of the day, it comes down to what's good for the environment and what's good for human health."
