Last year +Jeff Sullivan started a debate that got into, among other things, the hazards of BT (Bacillus thuringiensis), a natural bacteria culture that causes slow, apparently very painful, death for caterpillars but usually doesn’t bother humans at all. (Individual monarch caterpillars are vulnerable to BT; the species as a whole was not endangered by it.) BT is organic. Right. But we’re talking about three different possibilities with BT:
(1) The bacteria are naturally transmitted among insects, at a relatively low concentration. Humans are exposed to very few bacteria unless they eat or handle insects daily, which nobody we know does, right?
(2) The bacteria are cultured in laboratories and the culture is sprayed or poured, in much higher concentration, on vulnerable plants at the key time of year. Humans are exposed to more bacteria than they ever were before microscopes and systematic bacteria culturing were invented, but that’s still relatively few bacteria. (Human volunteers have demonstrated the ability to eat a cupful of live BT culture at a time without showing symptoms.)
(3) DNA from the bacteria is spliced into one or more foods that humans then unknowingly eat every single day over a period of years. Arguably humans are exposed to fewer living, “natural” bacteria than in the first two situations…but reality is that a small minority of humans (who apparently ate a great deal of BT-DNA-enhanced corn) have developed chronic symptoms that they describe in terms similar to the early stages of death-by-BT in infected caterpillars.
It’s not scientifically rigorous to say that pesticide A is “worse” than pesticide B; you have to specify how much of each pesticide under what conditions–and obviously the article linked below is comparing apples and oranges, in terms of the ways serious organic gardeners and small farmers use these pesticides. On the other hand, if we’re talking about commercial “organic” agribusinessmen thinking they can just substitute concentrated tobacco juice for “Roundup” or plant BT-spliced corn instead of spraying the corn with “Raid,” we could be talking about a serious health hazard. Potentially. If they’re trying to plant acre after acre of the same thing, year after year, and “protect” it by poisoning it instead of rotating crops the way serious organic farmers do…
Protecting our environment is not merely a matter of substituting one poison for another poison. We have to learn to raise food crops efficiently enough that nobody has to rely on poison.
This can be done, but it’s not a quick, easy process. Vegetable gardeners and “organic” farmers need to be prepared for a long haul.
Helicoverpa zea, the Corn Earworm Moth, used to be a rare species. This drab little moth is, perhaps surprisingly, not nearly so well protected against predators as the showy Monarch. The Monarch’s vivid colors warn most predators that they don’t want to eat it. Birds, bats, bugs, wasps, and other creatures prefer to eat the Corn Earworm Moth, which apparently tastes good to them. However, when humans started spraying insecticides on whole fields, Corn Earworm Moth populations exploded! The insecticides were killing predators more efficiently than pests. The Corn Earworm Moths reproduced faster than poisoned birds and bats did, and when the next generation of moths hatched, there weren’t enough predators to thin their populations.
(Credit: “Pollinator” at Creative Commons.) I grew up in a world that had probably ten times as many Corn Earworm Moths as the world had a hundred years earlier. According to Wikipedia…
…the caterpillars infest one ear of corn (or sorghum) apiece. This, I learned as a child, is not necessarily the case. The first year we tried planting corn without spraying a field that had been poisoned every year for several years, we hardly found an intact ear; three and four earworms per ear of corn were not uncommon, and the chickens got more of our fresh, organically grown corn than we did. It took about ten years for predator populations to recover, even locally, to the point where anybody could count on having intact ears of organically grown corn for dinner.
This is typical, Gentle Readers. The first year you stop poisoning a field, you’ll be raising insects and will need to find Green ways to kill the ones you can’t just throw to the chickens. It will take time to rebuild predator populations. You’ll need to rotate crops (sustainable agriculture involves rotating crops anyway) and hand-pick a lot of pests. We used to go out to the vegetable garden with a little jar in our pockets to pick up all the insects, so we could burn or drown them all at once instead of having to squish them on the ground. We tried all kinds of dodges like tying nylon stockings over ears of corn to discourage those corn earworms.
After ten or twenty years, though, all this effort will pay off in beautiful, healthy food. If you want an organic garden, don’t give up too easily. Organic gardening does work, even though the local ecology will need time to recover from the Vicious Spray Cycle. Most of the corn grown in my corner of the world today is earworm-free.