Posted: October 2014
Field Performance of Bt Transgenic Crops: A Review
Chinese scientists from the National Key Laboratory of Crop Genetic
Improvement at the Huazhong Agricultural University in China have reviewed
the performance of different crops that have been genetically modified to
produce an insecticidal protein (“Bt” crops). The authors are
proponents of genetic engineering and are interested in finding ways of
improving the performance of GM crops.
They review the follow traits:
The also review findings on:
Nitrogen assimilation and metabolism
Optimum population density
The review cites many different studies and highlights the variety of
results researchers find. Some examples:
Spatial and temporal expression of the Bt genes
Genotypic variation and inheritance of the Bt genes
Effects of abiotic factors on transgene expression
The review gives many such examples. Overall it shows how
context-dependent and unpredictable the performance of Bt crops is.
General, across-the-board claims are therefore misleading.
Yield in Bt crops is often, but not always, higher under severe
pest pressure, while when pest pressure is low, yield is not higher,
although farmers are still paying the premium price for the crop
Bt and non-Bt cotton have similar yields when farmers spray
additional insecticides to kill insects that are not killed by the
Bt crops often require greater planting density to have high
yields, but since there are higher harvest costs and higher seed costs for
Bt seeds, the higher yields do not necessarily mean higher profits.
The review can be accessed free-of-charge online at:
Wang, F., S. Peng, K. Cui et al. (2012). “Field Performance of Bt
Transgenic Crops: A Review,” Australian Journal of Crop Science
vol. 8, pp. 18-26.
Copyright 2014 The Nature