Spices are Becoming Organic Pesticides

"Killer spices" provide eco-friendly pesticides for organic fruits and veggies

Rosemary, thyme, clove, and mint are well-known spices that are emerging as organic agriculture's key weapons against insect pests.

Scientists in Canada are reporting new research on these so-called "essential oil pesticides" or "killer spices." These pesticides have added to the crop-preserving arsenal of organic growers and offer several advantages over their counterparts -- they're readily available and don't require lots of regulatory approval.

And they're safer for gardeners and farm workers, who are at high risk for pesticide exposure.

Murray Isman, Ph.D., of the University of British Columbia is developing these pesticides.

So, just what is it exactly about these spices that allow them to work their magic outside the kitchen? Here's Dr. Isman again:

"It turns out that some of these oils and some of the chemical constituents in the oils are neurotoxic to many types of insects. At least one of their actions, and we're not certain about all of their actions, one of their actions is they interfere with a neuromodulator in insects called octopamine. It's sort of an internal valium for insects, it sort of calms them down so their nervous systems
don't get overstimulated by external stimuli. If you remove that octopamine, which is what
some of these oils do, they get hyperexcited and eventually die."

These pesticides, usually a combination of spices diluted with water, have added to the crop-preserving arsenal of organic growers and offer several advantages over their counterparts. First, they are readily available and don't require lots of regulatory approval. Also, insects exposed to the spices are less likely to evolve resistance to the toxins. And, they're safer for farm workers, who are at high risk for pesticide exposure. 

"Some of these oils, as some other people have mentioned, are very good antimicrobials,
so they could be very useful against food spoilage organisms, for example. They are useful
against certain plant pathogenic fungi and bacteria, and they do have this phytotoxic effect
on plants, so at high concentrations they can be used as natural herbicides."

These "killer spices" aren't just limited to agricultural use. Some show promise in the home as eco-friendly repellents against mosquitoes, flies and roaches. And, perhaps as an unexpected bonus, these natural pesticides can have a pleasant, spicy aroma. Some in fact contain the same oils used in aromatherapy products, including cinnamon and peppermint.