Contents - Faperta

318 Biotechnological Approaches for Pest Management and Ecological Sustainability
Progress in Development of Insect-Resistant Transgenic Crops
The fi rst insect-resistant transgenic crop was fi eld-tested in 1994, and large-scale commercial
cultivation started in 1996 in the United States (McLaren, 1998). Since then, the area planted
to transgenic crops has increased from 1.7 million hectare in 1996 to over 100 million hectare
in 2006, and 21 countries grew transgenic crops ( James, 2007) (Figure 10.1). Most of the
area under transgenic crops is in the United States, followed by Argentina, Canada, Brazil,
India, and China. The transgenic crops include soybean, maize, cotton, and canola. Among
the traits deployed, most area has been planted to herbicide-resistant soybean, followed by
Bt maize and cotton, and herbicide-tolerant maize, cotton, and canola. Herbicide-tolerant
soybean, maize, canola, and cotton occupied 71% or 63.7 million hectare, followed by 18%
or 16.2 million hectare of Bt transgenic crops. Nearly one-quarter of the crop area planted
to transgenic crops is grown in developing countries, mainly in Argentina, China, South
Africa, and India, and over 75% of the farmers are small resource-poor farmers in developing
countries.
Much of the success in developing insect-resistant transgenic plants with genes from
Bacillus thuringiensis (Berliner) (Bt) has come from in-depth genetic and biochemical information
generated on this bacterium. Genes encoding for δ-endotoxins from B. thuringiensis
have been cloned since the 1980s (Schnef and Whiteley, 1981). Genetically modifi ed plants
with resistance to insects were developed in the mid-1980s (Barton, Whiteley, and Yang,
1987; Fischhoff et al., 1987; Hilder et al., 1987; Vaeck et al., 1987), and since then, there has
been rapid progress in developing transgenic plants with insect resistance in several crops
(Hilder and Boulter, 1999; Sharma, Sharma, and Crouch, 2004). The progress made in
development and deployment of insect-resistant transgenic plants with different toxin
genes for pest management in different crops is discussed below.
Effectiveness of Transgenic Crops for Controlling Insect Pests
Cotton
There is a clear advantage of growing transgenic cotton in reducing bollworm damage and
increasing cottonseed yield (Figure 10.2). Cotton plants with Bt genes are effective against
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0
1996
Global Area (Million Hectares) of Biotech Crops,
1996 to 2005: by Trait
Herbicide Tolerance
Insect Resistance
Herbicide Tolerance/Insect
Resistance
1997 1998 1999 2000 2001 2002 2003 2004 2005
FIGURE 10.1 Area under transgenic crops worldwide. (From Clive James, 2005.)
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