Hope Not Hype - Third World Network

66 Hope Not Hype
Does genetic engineering reduce use of pesticides
Have GM crops delivered on the claim that overall pesticide use has been reduced in
the agricultural systems that have adopted GM crops Early research indicated that
agrochemical applications on GM crops were less than on conventional crops and more of
these kinds of benefits could be expected in the future.
It is estimated that the use of GM soybean, oil seed rape, cotton and maize varieties modified
for herbicide tolerance and insect protected GM varieties of cotton reduced pesticide use by
a total of 22.3 million kg of formulated product in the year 2000. Estimates indicate that if
50% of the maize, oil seed rape, sugar beet, and cotton grown in the EU were GM varieties,
pesticide used in the EU/annum would decrease by 14.5 million kg of formulated product
(4.4 million kg active ingredient). In addition there would be a reduction of 7.5 million ha
sprayed which would save 20.5 million litres of diesel and result in a reduction of approximately
73,000 t of carbon dioxide being released into the atmosphere (Phipps and Park, 2002, p. 1).
“Pesticides” is a term that includes both insecticides and herbicides. Unbundling
these two types of agrochemicals also reveals some important statistical differences. GM
crops that produce their own insecticide (i.e., IR, PR, Bt, insecticidal crops) appear to
modestly reduce the amount of other kinds of insecticides made from agrochemicals that
were previously applied, at least until resistance or secondary pests might emerge and
reverse this trend (Pretty, 2001; Qiu, 2008), but this does not account for the extra organic
pesticide in the form of genetically engineered insecticidal proteins or dsRNA (see discussion
on GM papaya in Appendix One) introduced into the environment by the crop itself
(Appendix Three).
A different picture of insecticide reduction is obtained when crop types are separated
rather than grouped. For example, the maximum reduction in insecticide use comes from
the adoption of Bt cotton rather than maize.
[T]he conclusion that adoption of Bt cotton or maize may entail ecological benefits assumes
a baseline condition of insecticide applications. In reality, both types of control treatment
reflect farming practices: in 2005, insecticides were applied to 23% of maize acreage cultivated
in 19 states surveyed by the U.S. Department of Agriculture. Moreover, the vast majority of
Bt maize acreage comprises varieties used for silage or processed foods (e.g., corn syrup) for
which insecticide use has typically been limited. Insecticides are more commonly used in
cotton production, with 71% of surveyed cotton acreage treated in 2005 (Marvier et al., 2007,
p. 1476).
The reduction in insecticide use comes mainly from cotton but is usually reported in
the aggregate, implying that the benefit extends to all Bt crops. Furthermore, the data for
pesticide use is often from the US (Kleter et al., 2007) and may not extrapolate to other
parts of the world.