Researchers have previously developed genetically engineered (GE) rice lines that produce insecticidal Cry proteins from Bacillus thuringiensis (Bt) to control lepidopteran pests and minimize yield loss. However, before a Bt rice line can be cultivated, the risks to the environment must be assessed. This includes potential adverse effects on valued non-target arthropods (NTAs) and the ecosystem.
A team from the Chinese Academy of Agricultural Sciences and the Huazhong Agricultural University in China, as well as Agroscope in Switzerland had conducted a study to identify NTAs present in the rice-growing regions of Central and Southern China and their known food web interactions. The team also evaluated the level of exposure of the NTAs to the plant-produced Cry2A-protein during field experiments held in 2011 to 2012.
A total of 13 nontarget herbivores was collected and analyzed. Planthoppers, both nymphs and adults, contained trace amounts of Cry2A. In contrast, the level in smaller meadow katydids was almost 2.5 higher in samples collected. On the other hand, predators, especially spiderss did not contain measurable amounts of Cry2A and were much lower than those in plant tissues.
No Cry2A protein was detected in samples of predatory beetles collected before rice anthesis. However, the beetles and lacewings contained significant amounts during anthesis, but significantly lower than those in plant tissues. Parasitoids were also collected but Cry2A levels were below the limit of detection.
These data shows a reduction in Cry protein concentrations from lower to higher trophic levels. This is in accordance with field studies from other Bt-transgenic crops producing different Cry proteins.
For more on this study, read the article in Plant Biotechnology Journal.
-Published in ISAAA Crop Biotech Update. See original article link here.