Why novel GM Crop Traits are not fully utilized in Agroecological Farming Systems

1. Integration of GM Crop Traits in Agroecological
Practices in Europe: A Critical Review
(Hokkanen & Menzler-Hokkanen)
Daniel Wasonga
PhD Student
University of Helsinki
Daniel Wasonga
PhD Student
University of Helsinki
NOVA RNAi workshop
December12, 2017

2. Aim of the presentation
o Critical review of the possibility of GM crops
to provide benefits for biological control and
sustainable agroecological practices in Europe
o Give potential and shortcomings of GM crops
performance, and explain the present
reluctance in Europe to incorporate them as
an agroecological tool

3. Reality gap in IPM
o GM crops are not integrated
as a component in IPM
- Gap exists between
reductionist approach in
biotechnology, which focus on a
single solution to pest problems
and the holistic approach in
IPM, where an optimal
combination of pest control
tactics is the aim
o GM crops are seen by
growers as a standalone pest
management tool
• Tradition IPM pyramid- PM is
based to a large extent on
avoidance and use of chemical
pesticides is just a small tip of
the pyramid
• In reality, the pyramid is
upside down, most of actual
PM is done by chemical
pesticides.

4. Potential Benefits of GM crops:
i.Lower use of pesticides
ii.Improved biological control
iii.More efficient pest, disease and
weed control
iv.Improved possibility for IPM
v.Higher yields
Insect resistance in GM crops:
•Dramatically reduces pesticide
inputs
•Improves biological control and
other pests
•Conserves pollination services
•Improves crop productivity under
high target pest pressure
Herbicide Tolerance:
a.Usually increases herbicide
inputs
b.Interferes with biocontrol and
pollination by removing nectar
and pollen resources
c.But improves crop productivity
under high weed pressure

5. Mechanisms through which
natural enemies may be affected
by GM crops
Toxicity-mediated effects such as
toxicity of non-prey food items
(e.g. pollen) from GM crops
Changes in the crop environment
Conservation tillage – facilitated
by the use HT crops – and its
impacts on biological control
Toxic effects of herbicides used
with GM crops, affect arthropod
enemies.
Potential of GM crops as a
tool for sustainable
agroecological management
•Pest/disease resistant GM
crop may be considered as one
tool in the IPM toolbox
- The optimal toolbox for
any region will depend on
selecting the best IPM tools
that work together thus
increasing sustainability of
the IPM system

6. Advantages of GM transgenic insect resistance varieties
• New varieties can be obtained much faster than by
classical breeding
•Level of resistance achievable in GM plants is often
higher than resistance levels occurring naturally in the
gene pool of plant species
- since genes can be introduced from a wide variety of sources,
and linkage drag is minimized.
•In these GM crops, the exposure of non-target organisms is
significantly reduced, compared to pesticide spraying.
•Pests feeding on plant parts which normally cannot be reached by
pesticide sprays such as stem borers, are exposed to the transgenic
toxins and can be targeted with this technology.
•Transgenic resistance in Bt-plants is much more specific for the
target insect than most pesticides

7. IPM impacts of altered insecticide
use in GM crops
i) Lower/less frequent insecticide
treatments - will improve possibilities to
benefit from enhanced activity of
natural enemies in controlling pests and
weeds
ii) Fewer spray treatments - will allow a
better choice of their timing so that
natural enemies of key pests can be
protected
Integration of GM crops with the use of trap cropping
- Employing GM trap crops for managing pests and cultivating the main crop
within, using conventional varieties.
- Bt collard and Bt indian Mustard being used to protect cabbage from
diamondback moth damage.
RNAi techniques
-Transgenic plants expressing double-stranded RNA (dsRNA) is one delivery
method of the dsRNA product for insect control.
-Target insect feeds on the plant, mRNA levels of the selected gene in the target
herbivore are reduced, and this consequently affects insect development and
survival.

8. Herbicide tolerance as a component
tool in IPM
•Significant economic savings, yield
increases and more effective and
simple weed management have
contributed to the widespread
adoption of the technology.
•Initially, glyphosate resistant crops
allowed to reduce tillage significantly,
and reduced the overall impact of
weed management.
- Continuous use of glyphosate over broad areas rapidly facilitated the
evolution of glyphosate resistant weeds. This has resulted in increasing
again the use of tillage, and other herbicides together with glyphosate,
reducing the initial environmental benefits of glyphosate resistant crops.
- Difficult to consider HT crops as part of IPM, because they are
based on calendar treatments with synthetic herbicides such as
glyphosate.

9. Herbicide resistant in weeds
- Weed resistance to glyphosate - major
issue affecting farmers using GM HT
crops.
-35 weed species worldwide resistant to
glyphosate
Way forward
•Farmers advised to include other
herbicides with different modes of
action in combination of glyphosate.
These factors are influencing the mix,
total amount, cost and overall use of
herbicides in GMHT crops.
•Current intervention is to develop 2,4-D
and dicamba herbicide resistant maize
and soybeans as alternatives.
Effects of HT crops on
biodiversity
HT crops leads to reduction in
the diversity of the arable flora
(as demonstrated by Farm Scale
Evaluation (FSE).
- Weeds play a critical role in
facilitating pest control
ecosystem services by providing
nectar and pollen to foraging
parasitoids and predators, if
parasitoids lack nectar sources,
their longevity and fecundity
are strongly reduced. HT crops
are thus clearly working against
IPM principle no 1 (prevention)
as the natural enemy complex is
crippled.

10. Trap cropping and disease resistance
• Disease resistance in GM
crops is not widely
available
Pawpaw affected by PRSV Pawpaw free from PRSV
 Trap cropping based on
genetically engineered
plants can be effective in
controlling insect-
vectored pathogens, such
as papaya ringspot virus
(PRSV).
 PRSV is transmitted by
many aphids species in a
non-persistent manner,
making it exceptionally
difficult to control
through the use of
insecticides.

11. Conclusion
Unfortunately, GM crops are currently mostly introduced to the
growers as stand alone technology for pest and disease control,
without any real attempt to integrate them as a component in
IPM. The theoretical benefits of pest and disease resistant GM
crops are eroded by this approach