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Pesticide Toxicology Laboratory

ISU Entomology / Pesticide Toxicology Laboratory / Monarch larvae sensitivity to Bacillus thuringiensis-purified proteins and pollen

Monarch larvae sensitivity to Bacillus thuringiensis-purified proteins and pollen

Authors: Hellmich, R.L., Siegfried, B.D., Sears, M.K., Stanley-Horn, D.E., Daniels, M.J., Mattila, H.R., Spencer, T., Bidne, K.G., Lewis, L.C.
Journal, Volume, Year: Proceedings of the National Academy of Sciences, volume 98:11925-11930, 2001
Summary

Laboratory toxicity tests were conducted to determine the effects of toxins and pollen from Cry1Ab, Cry1Ac, Cry9C, and Cry1F Bt corn to monarch larvae. Monarch first instars were sensitive to Cry1Ab and Cry1Ac proteins, but not to Cry9C and Cry1F. Pollen contaminants were found to substantially influence results in pollen bioassay tests. Cry1Ab event 176 was the only transgenic corn pollen to consistently affect monarch larvae. Pollen from the other types of Bt corn were determined to have no acute effects on monarch butterfly larvae in field settings.

Comments

The registration of hybrids derived from event 176 will terminate in 2001. As a result, there should be a significant reduction in risk to monarchs. However, additional studies are needed to examine the lifetime and reproductive impact of the other types of Bt corn.