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Better Living through Chemistry

Observations from the Edge
Robert T. Nanninga
North County Times
June 7, 1999


Hot on the tail of news that genetically engineered corn is proving fatal to the monarch butterfly, Fallbrook avocado growers are now spraying pesticides on their trees, knowing that they will soon develop immunity to them. Yet still they spray.

For those of you out of the loop, the genetically altered Bt Corn has had genes from the bacterium bacillus thuringiensis spliced into its own. Monarch caterpillars eating the transformed pollen, sicken and die quickly, because the crystalline endotoxin in the pollen causes pathogens in the insect's stomach to be released into the body of the doomed caterpillar.

Unlike the European corn borer which actually competes with humans for food, the target of avocado growers is a relatively benign insect known as the avocado thrips. When I say benign, I am referring to the fact that avocado thrips, like the fruit on which they feed, are natives of Latin America and has evolved with the avocado tree over the course of time. This relationship is why they're called avocado thrips.

These insects, according entomologist Mark Hoddel, do not harm the edible part of the fruit, they merely create a scarring effect that results in "alligator skin." The proponents of pesticide use, claim this scarring inhibits the growth of avocados, as well as profit, because crops are measured in pounds. This species, which feeds only on avocados, is being poisoned to increase esthetics and market profitability. How sick is that?

Used to eradicate the Avocado Thrips are two pesticides, Veritran D, and Agri-Mek. Agri-Mek is also toxic to bees, fish, aquatic organisms and wildlife. Agri-Mek suppresses feeding by paralysing susceptible species, eventually leading to death from starvation. Veritan D, according to San Diego County Farm advisor Gary Bender, is virtually non-toxic to most beneficials. When one also considers that the president of the San Diego County Farm Bureau is also a North County avocado grower, it is safe to say that the war against this small insect has just begun.

We should all be concerned when the people who we entrust to feed us can be so cavalier about dumping pesticides into the environment. According to The Dictionary of Ecology and Environmental Science a pest is,"an animal or plant that is directly or indirectly detrimental to human interests, causing harm or reducing the quality and value of a harvestable crop or other resource.

Eventually the cumulative effect of all these chemicals will be felt in the populations of species that prey on the thrips, and the species that feed on them, all the way up the food chain. The question is, how many other species can we afford to label as pests before the whole system begins to break down. It is important to keep in mind that the king of the hill has the farthest to fall.

Since I'm on the subject of poisoning species that have the misfortune of existing contrary to the needs of humans, besides the known poisoning of squirrels along the Carlsbad coast, I have heard from several readers that there has been a remarkable decrease in squirrel sightings in the Oceanside coastal area as well. I guess like corn and avocados, beach front property is another resource we won't share with other species. I wonder what would happen to the insects or animals that eat the poisoned squirrels. Aren't sea gulls scavengers? But then again they're pests too, right?

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