Agriculture Reference
In-Depth Information
and yield-increasing ef ects have been
reported (Huang
et al
., 2005; Krishna and
Qaim, 2008).
In their
ex ante
study of Bt aubergine in
India, Krishna and Qaim (2008) projected
that the technology, which controls the
aubergine fruit and shoot borer, would
reduce chemical insecticide use by up to 50%
and increase yields by 40% on average. h is
will not only improve farmers' proi ts, but
will also lower market prices and thus
improve consumer access to vegetables. h is
could have positive nutrition ef ects among
the poor. Moreover, Bt aubergine will be less
contaminated with pesticide residues, which
have become a real health problem in some
parts of India. In spite of the expected
positive economic, environmental and
health ef ects, Bt aubergine - as the i rst GM
food crop to be commercialized in India -
has aroused controversial public debate.
After a careful review of the biosafety and
food safety data, the Genetic Engineering
Approval Committee, which is the respon-
sible authority in India (see Chapters 3 and
13), declared Bt aubergine to be safe and
approved this technology in October 2009
(Kumar, 2009). However, after a series of
public hearings, which were inl uenced
heavily by anti-biotech campaigns, the
Minister of Environment and Forests sus-
pended the commercialization of Bt auber-
gine for an indei nite period. h is example
demonstrates how much the regulatory
procedures, which should be science based,
are inl uenced by subjective views of certain
lobbying groups.
Also, for other pest-resistant GM traits
such as fungal, virus, nematode or bacterial
resistance, which are being developed in
dif erent crops, pesticide-reducing and yield-
increasing ef ects can be expected. As already
observed for Bt technologies, positive yield
ef ects will be more pronounced in develop-
ing countries, where pest pressure is often
higher and farmers face more severe con-
straints in controlling pest damage (Table
14.3). Especially in the non-commercial and
semi-commercial crop sectors, where tech-
nical and economic constraints impede a
more widespread use of chemicals, pest-
related crop losses are often 50% and higher
(Oerke, 2006). Based on conditions of pest
pressure and current crop protection, the
biggest yield gains are expected in South and
South-east Asia and sub-Saharan Africa.
h e ef ects of GM crops with tolerance to
abiotic stresses will also be situation specii c.
A drought-tolerant GM variety can lead to
substantially higher yields than conventional
varieties under water stress, whereas the
ef ect may be small when sui cient water is
available. Especially in the semi-arid tropics,
many small-scale farmers are operating
under drought-prone conditions, so that the
benei ts of drought tolerance could be
sizeable. In a study referring to eight low-
income countries in Asia and sub-Saharan
Africa, Kostandini
et al
. (2009) calculate
that the average yield gains of GM drought
tolerance traits may be 18% in maize, 25% in
wheat and 10% in rice.
While the development of drought-
tolerant varieties is a major priority both in
public and private sector crop improvement
programmes, biotech researchers are also
working on tolerance to other abiotic stress
factors such as heat, salinity, l ood and
Table
14.3.
Expected yield effects of pest-resistant GM crops in different regions. (From Qaim and
Zilberman, 2003.)
Availability of
chemical
alternatives
Adoption of
chemical
alternatives
Yield effect of
GM crops
Region
Pest pressure
Developed countries
Low to medium
High
High
Low
Latin America (commercial)
Medium
Medium
High
Low to medium
China
Medium
Medium
High
Low to medium
Latin America (non-commercial)
Medium
Low to medium
Low
Medium to high
South and South-east Asia
High
Low to medium
Low to medium
High
Sub-Saharan Africa
High
Low
Low
High
