Did you know that farmers who plant genetically engineered crops need to also plant some non-GE crops in the same field? It is supposed to delay pest resistance to Bt corn crops.
Chemical and biotech companies like Monsanto, Syngenta, Bayer et al. have a long history of blaming farmers for failures of genetically modified crops and herbicides. When crop yields don’t provide, when corn rootworm takes over, and when farmers have to hire extra help to hack down superweeds when they were promised an easier season – the companies will be the first to throw farmers under the tractor. They like to claim that farmers aren’t following proper pesticide management and planting “refuges.”
For a long time that reason was truly considered a factor. Then came RIBs – “refuge-in-a-bag.” That way, some non-Bt corn would be pre-included in the Bt seed mixture.
…previous studies have shown that refuges do not work well, for three reasons: farmers don’t comply with refuge requirements, pests are able to live and reproduce in Bt maize fields, and the non-Bt refuge plants become contaminated by cross-pollination with Bt toxin-producing genes (see “Refuge concept breaking down” in GMO Myths and Truths).
According to them, the study, “A challenge for the seed mixture refuge strategy in bt maize: impact of cross-pollination on an ear-feeding pest, corn earworm” – was actually funded in part by Monsanto and the USDA. This writer was unable to locate the full text. It was originally published in PLOS ONE, in November.
A major concern in RIB is cross-pollination of maize hybrids that can cause Bt proteins to be present in refuge maize kernels and negatively affect refuge insects. Here we show that a mixed planting of 5% nonBt and 95% Bt maize containing the SmartStax traits expressing Cry1A.105, Cry2Ab2 and Cry1F did not provide an effective refuge for an important above-ground ear-feeding pest, the corn earworm, Helicoverpa zea (Boddie).
Cross-pollination in RIB caused a majority (>90%) of refuge kernels to express ≥ one Bt protein. The contamination of Bt proteins in the refuge ears reduced neonate-to-adult survivorship of H. zea to only 4.6%, a reduction of 88.1% relative to larvae feeding on ears of pure non-Bt maize plantings. In addition, the limited survivors on refuge ears had lower pupal mass and took longer to develop to adults.
The study found that over 90% of maize kernels expressed at least one Bt protein. In addition, the surviving pests on the refuge plants did not thrive, meaning that no viable Bt-susceptible pest populations survived. (emphasis added)
This could mean that the lack of pest control was never the fault of farmers – that refuges simply do not work, and in the end show more complications from cross-pollination. Back to the drawing board for them. Please also see: Thanks for the Super Genes – Weeds Receive Transgenic Material From GMOs
Photo by Rich Sanders, USDA Natural Resources Conservation Service.
Recent posts by Heather Callaghan: