|Corn/maize field in South Dakota. Photo by Lars Plougmann (originally posted to Flickr as|
In the corn field],[CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)]
via Wikimedia Commons
These varieties have been genetically transformed to suffuse themselves with one or more artificial forms of insecticidal proteins modelled on those found in the soil bacterium, Bacillus thuringiensis, 'Bt'.
Bt crops are touted as needing less chemical insecticides: they are, therefore, safer for people and the environment, and are less expensive and more convenient for farmers. Nevertheless, nearly half of farmers who are choosing Bt maize this year are still intending to apply soil insecticides at planting time.
Several reasons have been given for this belts-and-braces tactic.
- Infestations by secondary pests moving into the ecological gap left by Bt's decimation of CRW are high on the list.
- Only 10 years after Bt crops targetting CRW were introduced, the development of resistant strains of the insect have become a number one concern.
- Soil insecticides are considered a “cheap insurance” against crop losses from root-pests. While commodity prices are high, growers are loath to risk any source of yield failure.
- Farmers may be jittery after the record-breaking warm temperatures in March last year which caused the early emergence of CRW, although this year's weather is less favourable to the pest.
Signs of farmer distrust of biotech crops?
Clearly Bt maize is not perceived as a 'silver bullet' against CRW damage. Nor is the crop realising the biotech dream of avoiding chemical pesticide applications with all the attendant risks, costs and inconvenience.
The biotech industry 'answer' to this apparent technical/PR failure is based on the idea that two silver Bt bullets must be better than one. Science, however, is finding that this latest assumption is, like all the other touted benefits of Bt maize, more wishful-thinking than fact. Check out Bt REFUGE THEORY UNRAVELS - May 2012.
- Susan Jongeneel, Expect more soil insecticide used with Bt hybrids, AG Professional, 1.04.13