Biotech Updates

Bt Maize Not Harmful to Ladybirds

September 16, 2010

In a study conducted in 2008, two-spotted ladybird larvae were harmed by feeding on solutions with Bt proteins. The results of that study was used to ban the cultivation of Bt maize in Germany. However, other scientists questioned the vague design of that particular study. Thus, Fernando Álvarez-Alfageme and colleagues at Agroscope Reckenholz-Tänikon Research Station ART, Switzerland, reassessed the possible impact of Bt proteins (Cry1Ab and Cry3Bb1) on two-spotted ladybirds. They used red spider mites as food source because among the organisms eaten by ladybirds, spider mites were found to accumulate the most Bt protein. Ladybird larvae were fed exclusively with red spider mites that ate Bt maize. Results showed that the mortality rate of these larvae was not significantly different from the control group, which were fed with red spider mites that ate conventional maize.

In another setup, the ladybird larvae were fed with pure Bt protein in a nutrient solution, which is ten times the concentration of that found in spider mites. There were no significant differences in the larval development of larvae fed with Bt protein and larvae fed with plain nutrient solution. They also tested feeding another group of larvae with nutrient solution containing toxic substances. This group exhibited significantly higher mortality and slower development rates compared to control and larvae fed with high concentrations of Bt protein. Thus, ladybirds are not affected by Bt proteins.

Read the full article released by Transgenic Research Journal at