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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Bt Plants on Non-Target Herbivores

Author
item Hellmich, Richard

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 11, 2002
Publication Date: N/A

Technical Abstract: A correspondence to Nature three years ago reported a preliminary laboratory study that suggested pollen from Bacillus thuringiensis (Bt) corn could be hazardous to the larvae of the monarch butterfly, Danaus plexippus. Young monarch larvae given no choice but to feed on milkweed, Asclepias curassavica, leaves dusted with heavy loads of pollen from Bt corn hybrid ate less, grew more slowly, and had a significantly higher mortality rate than larvae feeding on leaves dusted with nontransgenic pollen. Based on this study, the authors questioned the environmental safety of Bt corn and called for scientific investigations. These preliminary findings were largely misrepresented by mainstream media before the potential impact of Bt corn pollen on monarch populations could be adequately assessed. Such reports have heightened public awareness, increased scrutiny of transgenic plants in terms of potential environmental impact, and intensified one of the most controversial and polarizing issues to face agricultural scientists in recent memory. In response to the Bt corn pollen and monarch questions, several researchers have conducted detailed studies to evaluate the effects of Bt pollen on monarch larvae. Results of these collaborative studies were published in five papers in the Proceedings of the National Academy of Sciences USA. A formal risk assessment was conducted that addressed toxicity of Bt corn pollen, and whether or not monarch larvae are exposed to harmful levels of Bt corn pollen. Research suggests that Bt corn (excluding 176 corn) will have no acute effects on monarch butterfly larvae in field settings.

Last Modified: 7/25/2014
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