Crop Biotech Update

Effect of Bt Broccoli and Diamondback Moth on Host Foraging and Development of a Parasitoid

January 7, 2011

One of the issues about Bt technology is the effect of crystal (Cry) proteins from Bacillus thuringiensis (Bt) in the biological control of insects. Xiaoxia Liu of Cornell University and his colleagues investigated the effect of Bt/non-Bt broccoli and Cry-resistant/susceptible diamondback moth (Plutella xylostella) on the host foraging and development of an endoparasitoid Diadegma insulare.

Results showed that there is no difference between the parasitism rate and development of D. insulare thriving on suscepticle or Cry-resistant moth. D. insulare failed to live on susceptible moths that were fed with Bt broccoli. There was no significant difference in the parasitism rate, developmental period, pupal and adult weights of D. insulare that developed on Cry-resistant moth that fed on Bt broccoli or non-Bt broccoli.

They also tested the second generation of the parasitoid that inhabited the Cry-resistant moth and found no difference in its life parameters whether the moth ate Bt or non-Bt broccoli. Cry protein was found present in D. insulare and moths that ate Bt broccoli. Therefore, protein cry1AC is not harmful to the development and host resistance of parasitoid D. insulare even after two generations of exposure.

Read the paper published by Transgenic Research journal at