This paper is relevant to the impact areas in the following areas:
| Crops | Maize |
| Traits | Insect Res. (BT) |
| Countries | Spain |
| Regions | Europe |
| Tags | borer, economics, maize, Spain, yield |
This paper examines the farm level impact of use of this Bt insect resistant maize in Spain.
Spanish maize production, corn borer problems and conventional control measures In 2001/02, Spain planted 485,000 hectares of grain maize (11% of total EU plantings). Over 90% of this is irrigated. Bt maize is planted on 20,000-25,000 hectares (further expansion beyond this area has not occurred since 1998 due to a voluntary arrangement by the seed supplier Syngenta). The main locations where Bt maize is planted are Huesca, Zaragosa and Lleida provinces (regions of Aragon and Catalunya).
In terms of corn borer pressure all of the main regions where Bt maize is planted are regions with high or medium annual corn borer pest pressures; overall about a quarter of Spanish maize is probably in high corn borer pest pressure regions and a further 40% in regions with medium corn borer pest pressure
About 6%-20% of the Spanish maize crop area uses insecticide treatments to control corn borer attacks. Where used, treatment is applied either via irrigation water (for chlorpyrifos only) or by aerial (aeroplane) spraying. The average cost of treatment is �18-�24/ha treated via irrigation and �36-�42/ha treated by aerial spraying.
The majority of Spanish maize crops (35%-54% based in regions with medium to high corn borerpest pressure that do not use Bt seed plus 25% in regions with low infestation levels) do not use any active form of treatment for dealing with corn borer attack. This is mainly because of the variable nature of pest attack by year and location, a requirement to get the timing of spraying exactly correct (the 2-3 day period after eggs hatch) and this is not easy to arrange, the fact that eggs hatch over a three week period relative to the insecticide effectiveness period of a few days only, treatments are not very effective against borers that have already bored into stalks, limited awareness of the extent of damage and the perceived high cost of treatment.
The corn borer is estimated to cause an average of 15% yield loss in some regions of high annual corn borer pest pressure where no insecticides are used and an average yield loss of 10% in some regions even if insecticides are used but applied at sub-optimal times. Across the country the average yield loss is probably lower but within a range of 5%-7%
Impact of using Bt maize
The cost of Bt maize seed relative to comparable alternatives is �18-�31/hectare, although for the majority of users who obtain their seed via co-operatives the lower end of this range is more representative.
As the damage that corn borer can cause to yield varies by location, year, climatic factors, timing of planting, whether insecticides are used or not and timing of insecticide applications, the positive impact on yields of planting Bt maize varies. In the Huesca region where high infestation levels are commonplace the benefit is an average 10% yield improvement (ie, 1 tonne/hectare on a base yield of 10 tonnes/ha) where insecticide treatments were previously used and, 15% where insecticide treatments were not previously used. Other research across a number of regions but limited to 1997 put the yield improvement at an average of 6.3% (within a range of 2.9% to 12.9%) whilst in some areas of low/medium pest attack the average yield improvement over the last four years has been about 1%..
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The farm level impact of using Bt maize in Spain (held on an external server, and so may require additional authentication details)
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