The How Of Chemistry

Yesterday, I attended the Application of Natural Products in Organic Farming session, sponsored by the AGRO division. I went strictly for personal interest (I wanted to be a farmer when I was a child, and I sort of still do), not necessarily for journalistic reasons. I caught most of the session, but I started fading after the coffee break. Imagine my surprise, like a rush of adrenaline, when I heard mention of Chromobacterium subtsugae, a biocontrol agent I worked on at USDA during a thesislike project in high school. (I think I'm okay to say that--I had to sign a nondisclosure agreement, of course.) Marja E. Koivunen, the presenter who mentioned this bacterium, is vice president of R&D at Marrone BioInnovations, the company that has licensed this microbe from the lab I interned at. I had come in on the C. subtsugae project after more than a decade of research had already been done, and another seven years have passed since then. As an intern, you don't get to see the entire process from lead discovery to commercialization, just the tiny bits you get to work on in the three months before you have to move on and go back to school. It's the same with my internship at BASF, working on a fungicide (again, nondisclosure). I came in late in the process, worked on it a little bit, and left. I am pretty certain that the product has been released and is currently seeking regulatory approval, but no one confirmed that with me when I asked previously. It's amazing, to me, to have been just an intern and see what I had a hand in be released upon the world's markets. But then I wondered how, exactly, do these products work? What the products do and to whom/what is known, as it must be for EPA approval, but EPA doesn't necessarily care what exactly the active compounds are or how exactly they do their job: EPA only really cares about toxicity data, according to some of the presenters at the session. I myself am very interested in the mode of action of pesticides. After all the mice, rat, nontarget organism toxicity, whatever testing is done, I might not worry about dying from spraying something on my tomatoes. But I like to know why the compound does what it does and how it acts while it's doing it. The closest any presenter came to satisfying that desire for me was Murray B. Isman, from the University of British Columbia, in Vancouver. His research on rosemary oil as a biopesticide revealed that of the 10 most prevalent compounds (out of a total of 70 or so) in the oil, only five have toxicity to target organisms. But the five inactive ingredients are needed for the mix to achieve its most lethal potential. How do these compounds work together and why are nontoxic ones needed to achieve high efficacy levels? That's an unknown. Knowing only whether a product works doesn't satisfy me; I'm still curious. Is it truly all about efficacy? Does it not matter how insects, plants, fungi, and other pests are controlled, just that they are without much (or at least negligible) damage to other organisms? As a consumer of such products, I would really love to know the "how" of these control methods well before I decide to use them where I live--and I might have to wait a long time before that's ever known.

Author: Kenneth Moore

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