Study by Klümper and Quaim
Klümper and Quaim showed in a broad Meta-Analysis that
in GM cultures the use of chemical pesticides can be reduced by 37%. This
decrease of insecticides use is caused by insecticides resistant (IR) plants. The
amount of herbicides in herbicides tolerant (HT) plants could not be reduced, there
is even a statistically not relevant increase. This difference is evident
because IR plants prevent damages from insects and make the use of chemicals
against them unnecessary, HT plants on the other hand just have the benefit
that several herbicides can be replaced by one different. A very interesting point
in this paper is the fact that they showed that the results from independent studies
does not much differ from studies paid by the industry.[1]
Study by Benbrook
In the study of Benbrook there are converse results.
He found a total increase of pesticide use in GM cultures. He also quantifies
an overall decrease of insecticide use and an increase of herbicide use, but in
this study there is a plus in herbicide use in total.[2]
This difference between these two articles could be
explained by the designs of the two papers. Klümper and Quaim compared studies
from all around the world published since 1999 (see Table S1 of their paper).
Benbrook in comparison used data from the United States and compared the
different years. He found a constant increase in pesticides use because of
resistant weeds and insects. Maybe this effect is not included properly in the
Klümper and Quaim studies because they have older material and in other
countries than the U.S. GM plants are not used for such a long time and
resistances had no time to develop.
Debate around the Benbrook study
The study of Benbrook is criticised by several
scientists and organisations. In an online article on geneticliteracyproject.org
Graham Brookes of PG Economics said, Benbrook made some subjective estimations
about his data.[3]
In the same article it is written that Brookes has made his own study with the
same data with contradicting results. But this study is made with data from all
around the world and so there is the same problem with resistant weeds and
insects mentioned in the last paragraph.[4] This is not good
researched or intended false information by this site. Another point that makes
me sceptical about this issue is the massive critic on PG Economics because of their
close bounds to the industry. (See my comment in Bettinas first blog)
Conclusion
Working on this blog showed me again what a controversy
theme GM plants and that there is lot of biased and false information on the
web and even in scientific papers. Not only from the industry with their
financial interests but also from the Anti-GM movement. I think this is a sign that
science got a massive problem with independency especially in a field like biotechnologies
where a lot of money is needed to conduct studies. For future work on this topic
I will use sources very thoughtful and always check the authors’ background.
[1] Klümper, W., Qaim, M. (2014). A Meta-Analysis of the
Impacts of Genetically Modified Crops. PLoS ONE 9(11)
[2] Benbrook, C.M. (2012). Impacts
of genetically engineered crops on pesticide use in the U.S. - the first
sixteen years. Environmental
Sciences Europe 24.
[3]Entine, J.: Scientists challenge
organic backer Benbrook claims that GM crops increase pesticide spraying. Found
the 13. April 2015 on: http://www.geneticliteracyproject.org/2012/10/scientists-journalists-challenge-organic-scientist-benbrook-claims-that-gm-crops-increase-pesticide-spraying-harm-the-environment/
[4]Brookes G., Barfoot, P.
(2012). GM Crops & Food. Biotechnology in Agriculture and the Food
Chain
3(2).
