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Pesticide Toxicology Laboratory

ISU Entomology / Pesticide Toxicology Laboratory / Rapid degradation of the Cry1F insecticidal crystal protein in soil

Rapid degradation of the Cry1F insecticidal crystal protein in soil

Authors: Herman, R.A., Wolt, J.D., Halliday, W.R.
Journal, Volume, Year: Journal of Agricultural and Food Chemistry, volume 50:7076-7078, 2002
Summary

The stability of the Cry1F toxin in an agronomic soil was examined using a Heliothis virescens bioassay. The protein used was the recombinant protein, not the transgenic protein. The bioassay utilized growth inhibition as its reporting variable, but counted mortality as zero growth. The decay relationship was modeled with a shift-log relationship, which is not a mechanistically-based model, but fit the data well. Found a DT50 (time for 50% dissipation) of 0.6 days and a DT90 of 6.9 days.

Comments

Did not use transgenic material. The DT50 and DT90 vales fit with some previous studies, but not with others, although most other studies were not with this particular protein. Counting mortality as zero growth was a poor choice and a potential misrepresentation. Mortality and growth might not be governed by the same mechanism and the individuals that died could actually have grown before dying.