Cry1Ab protein levels in phytophagous insects feeding on transgenic corn: implications for secondary exposure risk assessment
Authors: Head, G., Brown, C.R., Groth, M.E., Duan, J.J.
Journal, Volume, Year: Entomologia Experimentalis et Applicata, volume 99:37-45, 2001
Used ELISA and bioassay with 1st instar European corn borer to measure Cry1Ab (from Mon 810) protein levels in insects (Rhopalosiphum maidis, Ostrinia nubilalis, Helicoverpa zea, and Agrotis ipsilon) feeding on transgenic corn (8-13 ppm protein in green leaves) or artificial diet fortified with purified protein. R. maidis was not susceptible; the other species had varying degrees of sensitivity. The insects were reared on transgenic corn or the diet and large numbers were pooled and homogenized for detection of protein. Found protein in all of the artificial diet treatments (20, 100, or 200 ppm protein in diet). Found no protein in aphids feeding on plant. ELISA detected protein in all larvae that were fed on transgenic plants. No mortality was seen when these larvae were used in bioassay with 1st instar ECB. Biomass of ECB was reduced in the bioassay using lepidopteran larvae that were fed the 20 or 100 ppm diet.
Good study. Showed both real situation with transgenic plants, and a worst-case type situation with higher levels of protein. Lowest level of diet incorporated protein was only about 2x the expression in plants, but ECB weight was observed to be significantly lower than control. Indicates that if plants were to be produced that expressed higher levels of protein, there would be potential for adverse effects. Long-term feeding may also be of concern.