Butterflies and Milkweed

* Jeremy Rifkin (Commentary, June 1) took a giant leap by suggesting that a laboratory study with monarch butterflies justifies a worldwide ban on agricultural biotechnology.

The study showed that when monarch caterpillars eat enough pollen from corn containing a bacterial gene, they can be adversely affected. However, the study also showed that caterpillars apparently don’t like to eat corn pollen, with or without the gene.

In the laboratory, the caterpillars had no choice during four days of observation. Two groups were fed milkweed covered with pollen (genetically modified or normal) and another had undusted leaves. Caterpillars on the plain milkweed started eating sooner and ate more leaves than either group that had to eat pollen. This suggests that in their natural setting the monarchs would steer clear of pollen on their only food--milkweed leaves.

Caterpillars should have no trouble avoiding corn pollen in their natural environment. Milkweeds have many large leaves and tend to grow in clumps. If the top leaves were dusted by windblown pollen, the caterpillars could simply feed on lower leaves or move to another plant. Furthermore, monarchs prefer mature milkweeds, which are more commonly found in ditches, forest edges and stream banks remote from production fields.

In nature, timing is everything. For any harm to occur, the caterpillars have to be present during the brief time when corn is pollinating. They have to consume the pollen before rain washes it away.

WARREN DOUGLAS

STEVENS PhD, Senior Curator

Missouri Botanical Garden

St. Louis

* Rifkin hit the nail on the head with his commentary on genetically engineered food crops. A moratorium is absolutely necessary if we are to protect future generations of Americans and the rest of the world. Monsanto and Novartis should take more responsibility in this by letting all of us know what crops are already engineered and/or sprayed with the toxin gene Bt.

Foods are supposed to be the one natural thing we can do for our health and our bodies, and now that is being tampered with. This is truly frightening.

BONNY LaMONICA

Redondo Beach