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General Information

Document type
  • Peer-reviewed journal article
GE organism
  • maize
GE trait
  • insect resistance
  • USA, Canada


Safety for environment
  • no effect

Monarch larvae sensitivity to Bacillus thuringiensis- purified proteins and pollen Open Access

Hellmich, RL; Siegfried, BD; Sears, MK; Stanley-Horn, DE; Daniels, MJ; Mattila, HR; Spencer, T; Bidne, KG; Lewis, LC
Proceedings of the National Academy of Sciences UsA. 2001 October. 98(21):11925-11930

Link to full text (open access, freely available)

PMID: 11559841 DOI: 10.1073/pnas.211297698


Laboratory tests were conducted to establish the relative toxicity of Bacillus thuringiensis (Bt) toxins and pollen from Bt corn to monarch larvae. Toxins tested included Cry1Ab, Cry1Ac, Cry9C, and Cry1F. Three methods were used: (i) purified toxins incorporated into artificial diet, (ii) pollen collected from Bt corn hybrids applied directly to milkweed leaf discs, and (iii) Bt pollen contaminated with corn tassel material applied directly to milkweed leaf discs. Bioassays of purified Bt toxins indicate that Cry9C and Cry1F proteins are relatively nontoxic to monarch first instars, whereas first instars are sensitive to Cry1Ab and Cry1Ac proteins. Older instars were 12 to 23 times less susceptible to Cry1Ab toxin compared with first instars. Pollen bioassays suggest that pollen contaminants, an artifact of pollen processing, can dramatically influence larval survival and weight gains and produce spurious results. The only transgenic corn pollen that consistently affected monarch larvae was from Cry1Ab event 176 hybrids, currently <2% corn planted and for which re-registration has not been applied. Results from the other types of Bt corn suggest that pollen from the Cry1Ab (events Bt11 and Mon810) and Cry1F, and experimental Cry9C hybrids, will have no acute effects on monarch butterfly larvae in field settings.


Bt; butterfly; Monarch; corn


Funding source
  • USDA
  • Agricultural Biotechnology Stewardship Technical Committee
  • Canadian Food Inspection Agency
  • Environment Canada
  • Ontario Ministry of Agriculture
Funding country
  • United States
  • Canada
Funding type
  • government
  • industry: same

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Cite this study


Hellmich, RL, BD Siegfried, MK Sears, DE Stanley-Horn, MJ Daniels, HR Mattila, T Spencer, KG Bidne, LC Lewis. "Monarch larvae sensitivity to Bacillus thuringiensis- purified proteins and pollen." Proceedings of the National Academy of Sciences UsA 98.21 (2001): 11925-11930. Web. 22 Jun. 2024.


Hellmich, RL., Siegfried, BD., Sears, MK., Stanley-Horn, DE., Daniels, MJ., Mattila, HR., Spencer, T., Bidne, KG., & Lewis, LC. (2001). Monarch larvae sensitivity to Bacillus thuringiensis- purified proteins and pollen. Proceedings of the National Academy of Sciences UsA, 98(21), 11925-11930. doi:10.1073/pnas.211297698

Please verify citations before use, citations are automatically generated based on information stored within the GENERA database and therefore may or may not be correct.