Recent research suggests that the use of genetically modified insect-resistant crops can have a beneficial effect on surrounding non-transgenic crops. It is suggested that this may be due to a decline in the regional population of the pest Ostrinia nubilalis (European corn borer). The European corn borer is economically significant to maize farmers, with heavy infestations causing estimated yield losses of up to 25% (Myers et al).
Bt maize expresses insecticidal proteins
The bacterium Bacillus thuringensis (Bt) has long been known to display insecticidal properties. It produces a range of endotoxins, proteins causing death to insects when ingested. Over 130 of these proteins have been identified to date; each protein only being active in only a few insect species (de Maagd et al, 1999).
In 1993, Koziel et al reported excellent resistance of a transgenic line of maize plants to the European corn borer. The transgenic plants were created by incorporating a synthetic gene containing a truncated version of one of the endotoxin proteins from B. thuringensis.
Transgenic Bt widely planted in US
Bt maize has been increasingly widely used by farmers in the US during the past decade, since its introduction by Monsanto in 1996. In 2009, the National Agricultural Statistic Service reported that 17% of all maize (corn) planted in the US was transgenic Bt maize.
This widespread planting of Bt maize has led to concerns that resistance to transgenic crops may develop, and scientists recommend that farmers should maintain a refuge of non-transgenic maize representing at least 5% of the total planted area in order to ensure a healthy population of non-resistant pests is preserved (Alsted and Andow, 1996)
Bt maize causes area-wide effects
In a new study by Hutchison et al (2010), the population of European corn borers as estimated from larval surveys was compared with the proportion of Bt maize crops in five US states. Researchers observed a decline in the population of European corn borers in non-Bt maize fields, believed to be due to the growing of Bt maize crops in nearby areas. On the basis of their studies, the researchers estimated that use of Bt maize had led to cumulative benefits of $6.9 billion over the past 14 years, of which $4.3 billion was estimated to benefit non-Bt maize growers.
Sources
SW Myers, M Ballweg, JL Wedberg “Assessing the Impact of European Corn Borer on Corn Grown for Silage” Focus on Forage 3:1-3
“Acreage” Agricultural Statistics Board Report 2009
RA de Maagd, D Bosch, W Stiekema “Bacillus thuringiensis toxin-mediated insect resistance in plants” Trends in Plant Science 4:9-13 (1999)
MG Koziel, GL Beland, C Bowman “Field performance of Elite Transgenic Maize Plants Expressing an Insecticidal Protein Derived from Bacillus thuringensis” Nature Biotechnology 11:194-200 (1993)
DN Alsted, DA Andlow “Implementing Management of Insect Resistance to Transgenic Crops” AgBiotech News and Information 8:177-181 (1996)
WD Hutchison, EC Burkness, PD Mitchell “Areawide Suppression of European Corn Borer With Bt Maize Reaps Savings to Non-Bt Maize Growers” Science 330:222-225 (2010)
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Genetically Modified Corn Varieties Grown in the US
Veronica Mitchell - Veronica studied veterinary medicine at Cambridge University before becoming a secondary school science teacher. She enjoys writing about ...
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