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Milkweeds
Cardioactive glycosides
Similar to digitalis
Can hurt livestock, Monarch caterpillars and people
Click picture for details |
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Monarch Butterfly, BT Corn and Milkweed
The caterpillar, or larval stage, of this insect feeds on
milkweed. Bt-corn pollen, like
any corn pollen, is blown by the wind onto milkweed and other plants in the
vicinity of Bt-corn fields. Monarchs lay eggs on milkweed.
The larval |
| eat the milkweed and die within 4 days. |
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http://www.ipm.iastate.edu/ipm/icm/1999/6-14-1999/monarchbt.html
A study from Cornell University in New York was recently published in the science
journal Nature and suggests that pollen from Bt corn may have toxic effects on larvae of the
monarch butterfly. The caterpillar, or larval stage, of this insect feeds on milkweed. Because
some milkweed grows next to corn in the Midwest, there is the potential that Bt corn pollen may
drift onto milkweed and affect monarch larvae. The Cornell study has generated a tremendous
amount of coverage in the national media because of the potential clash between biotechnology
and wildlife.
Bt corn produces a specific toxin,
originally derived from a soil microorganism, Bacillus thuringiensis. In its natural form, the
toxin, when eaten, is fatal to caterpillars of moths and butterflies. Industry scientists
engineered corn plants to produce this Bt toxin in order to kill European corn borers that feed
on corn plants.
In many Bt-corn varieties, the toxin is produced in
most plant tissues, including pollen. Since monarch caterpillars do not feed on corn, they might
be expected to be in no danger from Bt corn. But Bt-corn pollen, like any corn pollen, is blown
by the wind onto milkweed and other plants in the vicinity of Bt-corn fields.
Also see: http://www.ars.usda.gov/is/br/btcorn/ |