>>However, even the mindset that we need *more* toxins in plants because insects are becoming resistant to the current arsenal of insecticides seems to me the wrong way of solving the problem.
>So you get your choice, corn that looks out for itself locally, or gets bombed from the air. Those are the real alternatives.
The first observation is a good example of the need to incorporate evolutionary considerations into other areas of biology-in this case, better thinking about the evolutionary abilities of the pest.
Actually, it may be possible to address both of these problems. The key is that insecticide is not the only way for corn to look out for itself. Certain passionflower vines have developed what seems to be foolproof caterpillar defense. They grow tiny hooks that puncture insect larvae, causing them to bleed to death. Passionflowers are not at all closely related to corn, but they are a lot closer than the bacteria from which the pesticidal gene was derived, so perhaps the gene for the hooks could be transferred.
Part of the problem is also economics. A highly specific pesticide (such as a species-specific virus) poses minimal threat to other organisms, but also can only be used for the specific pest. Popular pesticides generally kill everything, good or bad, so they can be marketed more widely. For example, gypsy moths, major pests of forests in the eastern U.S., have regular population crashes due to a virus. Spraying this virus over an infested region would effectively stop the problem. However, no one wants to spend the money to grow enough gypsy moths in the lab to produce a commercial supply of virus. Despite the large potential, it is still much more cost-effective to manufacture a general insecticide.
Dr. David Campbell
"Old Seashells"
Biology Department
Saint Mary's College of Maryland
18952 E. Fisher Road
St. Mary's City, MD 20686-3001 USA
dcampbell@osprey.smcm.edu, 301 862-0372 Fax: 301 862-0996
"Mollusks murmured 'Morning!'. And salmon chanted 'Evening!'."-Frank Muir, Oh My Word!
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