Crop Biotech Update

Study Shows that Beneficial Insects Unharmed by Bt Crops

February 5, 2014

Big-eyed bugs (Geocoris punctipes) and insidious flower bugs (Orius insidiosus) are predators present in different important crops such as cotton and maize, where they play beneficial roles by feeding on various pests, including eggs and small larvae of caterpillars.

To investigate the effect of three Cry proteins used in Bt crops on the life history of these predators, a study was conducted by Jun-Ce Tian of Cornell University and colleagues. To eliminate the confounding prey quality effects that can be introduced by Bt susceptible prey, the researchers used Cry1Ac/Cry2Ab-resistant cabbage looper (Trichoplusia ni) and Cry1 F-resistant fall armyworm (Spodoptera frugiperda) in a series of tri-trophic studies.

Results showed that survival, development, adult mass, fecundity, and fertility were similar when predators consumed larvae feeding on Cry1Ac/Cry2Ab cotton or Cry1 F maize compared with prey feeding on isogenic or near-isogenic cotton or maize. Frequent contact of the same initial group over a second generation also led to no differences in life-history characteristics when feeding on non-Bt- or Bt-fed prey. Further analysis showed that predators were exposed to Bt Cry proteins from their prey and that these proteins became increasingly diluted as they moved up the food chain. Results show a clear lack of effect of three common and widespread Cry proteins on these two important predator species.

Read more on the study at http://www.ingentaconnect.com/content/esa/envent/2014/00000043/00000001/art00026.