Genetically engineered cotton producing the Cry1Ac toxin from
Bacillus thuringiensis (Bt) has been commercially cultivated in
northern China since 1997. Approximately 10,000 ha were planted
initially, and by 2009, it had expanded to 3.7 million ha, accounting
for 90% of the cotton produced in the region (James, 2009). The
deployment of Bt cotton has effectively controlled the cotton bollworm
Helicoverpa armigera (Hübner) and reduced the need for
insecticide sprays (Wu et al., 2008). However, the widespread
planting of transgenic crops has raised concerns about the impact
on non-target herbivores, as well as on beneficial insects (Sisterson
et al., 2004).