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Record information and status
Record ID
Date of creation
2012-05-04 16:06 UTC (dina.abdelhakim@cbd.int)
Date of last update
2012-05-08 13:26 UTC (andrew.bowers@cbd.int)
Date of publication
2012-05-08 13:26 UTC (andrew.bowers@cbd.int)

General Information
Impact of Bt corn pollen on monarch butterfly populations: A risk assessment
Mark K. Sears, Richard L. Hellmich, Diane E. Stanley-Horn, Karen S. Oberhauser, John M. Pleasants, Heather R. Mattila, Blair D. Siegfriedi, and Galen P. Dively
Author’s contact information
Mark K. Sears

Department of Environmental Biology,
University of Guelph,
Guelph, ON,
Canada N1G 2W1

E-mail: msears@evb.uoguelph.ca.
  • English
Publication date
Summary, abstract or table of contents

A collaborative research effort by scientists in several states and in Canada has produced information to develop a formal risk assessment of the impact of Bt corn on monarch butterfly (Danaus plexippus) populations. Information was sought on the acute toxic effects of Bt corn pollen and the degree to which monarch larvae would be exposed to toxic amounts of Bt pollen on its host plant, the common milkweed, Asclepias syriaca, found in and around cornfields. Expression of Cry proteins, the active toxicant found in Bt corn tissues, differed among hybrids, and especially so in the concentrations found in pollen of different events. In most commercial hybrids, Bt expression in pollen is low, and laboratory and field studies show no acute toxic effects at any pollen density that would be encountered in the field. Other factors mitigating exposure of larvae include the variable and limited overlap between pollen shed and larval activity periods, the fact that only a portion of the monarch population utilizes milkweed stands in and near cornfields, and the current adoption rate of Bt corn at 19% of North American corn-growing areas. This 2-year study suggests that the impact of Bt corn pollen from current commercial hybrids on monarch butterfly populations is negligible.
Thematic areas
Background material to the “Guidance on risk assessment of living modified organisms”
Is this document is recommend as background material for the “Guidance on Risk Assessment of Living Modified Organisms”
Section(s) of the “Guidance on Risk Assessment of Living Modified Organisms” this background material is relevant
Additional Information
Type of resource
  • Article (journal / magazine / newspaper)
doi: 10.1073/pnas.211329998
Publisher and its location
Proceedings of the National Academy of Sciences (PNAS), National Academy of Sciences, Washington, DC
6 page PDF
Proceedings of the National Academy of Sciences (PNAS)
Keywords and any other relevant information

PNAS October 9, 2001 vol. 98 no. 21 11937-11942