can genetically modified plants play a role in sustainable ... · can genetically modified plants...
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Can genetically modified plants play a
role in sustainable crop protection?
Franz Bigler, Olivier Sanvido and Jörg Romeis
Agroscope Research Station ART
Zürich, Switzerland
Crop losses in major crops and the role
of crop protection
Oerke and Dehne (2004) Crop Protection 23:275-285
83
82
80
71
66
60
50
48
27
30
42
39
33
28
29
27
0 20 40 60 80 100
Sugar beet
Cotton
Rice
Potatoes
Maize
Soybean
Wheat
Barley
Crop loss rate (in % of attainable yield)
Actual loss (despite crop protection)
Potential loss (without crop protection)
Global adoption rates of GM crops 2008
Maize
30%
Cotton
12%
Oilseed rape
5%
Soybean
53%
by crop by trait
James 2008 ISAAA brief no. 39
Insect
resistance
(IR); 15% Herbicide
tolerance
(HT); 63%
stacked; 22%
Integrated Pest Management – a
sustainable way of crop protection
Integrated Pest Management (IPM) is a
crop protection strategy utilising all
suitable methods and techniques which
are compatible with economic, ecological
and social requirements to keep damaging
organisms below economic injury levels
(FAO 1965 & 1980)
Integrated Pest Management – a
sustainable way of crop protection
Integrated Pest Management (IPM) is a
crop protection strategy utilising all
suitable methods and techniques which
are compatible with economic, ecological
and social requirements to keep damaging
organisms below economic injury levels
(FAO 1965 & 1980)
New EU directive requesting IPM of all EU
farmers by 2014
Pest Biology& Ecology
Culturalcontrol
Quarantine,Eradication
Sampling,Monitoring & Forecasting
Economic thresholds
Pesticides etc.
Resistance Manag.
Avoidance,Prevention
Pesticides & other direct methods
Integrated PestManagement
Sampling,Thresholds
(Courtesy of Steven Naranjo, adapted)
Biological control
Host plantresistance
The ideal pest resistant plant from an IPM
perspective?
1. Control of key pests with high efficacy (below economic injury level)
2. No/less direct control measures needed (e.g. insecticides)
3. No resurgence of target pests
4. Non-target pests have same or lower pest status (no secondary pest outbreaks)
5. No adverse effects on natural enemies (biological control)
6. Preservation of other ecosystem services (e.g. pollination, decomposition)
7. Low risk of pest resistance
8. No negative landscape effects (e.g. ecological functions preserved)
9. Economic benefits (e.g. high yield and quality)
10. Social benefits (e.g. low toxicological risks)
Control of key arthropod pests by
commercialized Bt crops
Bt cotton (Naranjo et al. 2008)
28 lepidopteran pest species listed:
9 excellent control, 13 good control, 5 some control, 1 no control
No control of Hemiptera, Coleoptera, Thysanoptera, Acari
Bt maize (Hellmich et al. 2008)
15 lepidopteran pest species listed:
7 stemborers (5 excellent control, 2 good control)
8 other Lepidoptera (3 good control, 4 some control, 1 no control)
1 coleopteran pest with good control
No control of Hemiptera, other Coleoptera, Diptera, Thysanoptera,
Acari
Country Number of
sprays
% change
Pesticide
(Kg/ha)
% change
Yield
% change
Refs
Argentina -52 -55 +32 Qaim et al., 2003
USA -35 +3 Williams, 2003;
Cattaneo et al., 2006
Australia -80 -85 +0.5 Fitt 2003, 2005;
Pyke 2004, 2007
India -42 -65 +75 to + 230 Qaim 2003;
Qaim & Zilberman 2003;
Bamberwale et al., 2004
China -60 -70 + 3 to +19 Pray et al., 2002;
Huang et al., 2003;
Lu et al., 2002
Sth Africa (small
farms)
-56 -24 +34 to +80 Yousef et al., 2001;
Ismael et al., 2002;
Kirsten et al., 2002;
Bennett et al., 2003;
Hofs et al., 2006
Sth Africa (large
farms)
-56 +20 Kirsten et al., 2002;
Gouse et al., 2003
Mexico -54 +11 Traxler et al., 2001
Bt cotton - impact on insecticide use and yield(Fitt, 2008)
Effects of Bt crops on abundance of biological control insects
compared to unsprayed non-Btcrops
GeocorisOriu
s
Chrysoperla
Coleomagilla
Macrocentrus
Eff
ec
t s
ize
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.618
93 3993
37
Wolfenbarger et al. 2008, PLoS OneCourtesy of S. Naranjo
Effects of Bt crops on abundance of biological control insects
compared to unsprayed non-Btcrops
GeocorisOriu
s
Chrysoperla
Coleomagilla
Macrocentrus
Eff
ec
t s
ize
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.618
93 3993
37
Wolfenbarger et al. 2008, PLoS One
Explanation:
Marocentrus grandii, a specialist parasitoid of
the European corn borer, is absent in Bt maize
because of absence of its target host.
Effects of Bt plants on
conservation biological
control
Natural enemy abundance and biological control are
significantly enhanced in Bt crops when compared
to insecticide-treated conventional fields
Romeis et al. (2006) Nature Biotechnology 24: 63-71
Marvier et al. (2007) Science 316: 1475-1477
Wolfenbarger et al. (2008) PLoS ONE 3(5): e2118
Potential landscape effects of GM crops
4 scenarios under GM crops adoption and IPM implications:
• Stable crop area reduced pesticide use with positive
effects on biodiversity and ecosystem services (e.g.
biocontrol, pollination)
• Increased crop area (additional incentives): less diverse crops
and non-crop areas may reduce ecosystem services
(e.g. biofuel production, see Landis et al. 2008)
• Areawide reduction of target pest(s) less pesticide use
(e.g. pink bollworm USA) positive effects on landscape level
• Areawide increase of non-target pests (secondary pest
outbreaks) negative landscape level effects (depending
e.g. on additional pesticide use)
Country N Sprays
% change
Pesticide
(Kg/ha)
% change
Yield
% change
Refs
Argentina -52 -55 +32 Qaim et al., 2003
USA -35 +3 Williams, 2003;
Cattaneo et al., 2006
Australia -80 -85 +0.5 Fitt 2003, 2005;
Pyke 2004, 2007
India -42 -65 +75 to + 230 Qaim 2003;
Qaim & Zilberman 2003;
Bamberwale et al., 2004
China -60 -70 + 3 to +19 Pray et al., 2002;
Huang et al., 2003;
Lu et al., 2002
Sth Africa (small
farms)
-56 -24 +34 to +80 Yousef et al., 2001;
Ismael et al., 2002;
Kirsten et al., 2002;
Bennett et al., 2003;
Hofs et al., 2006
Sth Africa (large
farms)
-56 +20 Kirsten et al., 2002;
Gouse et al., 2003
Mexico -54 +11 Traxler et al., 2001
Bt cotton - impact on insecticide use and
yield (Fitt, 2008)
Conclusions
• Current GM crops play a major role in some
IPM systems with benefits for farmers and the
environment
• GM crops have broadened opportunities for
other IPM tactics such as biological control
• Intelligent resistance management will be a
key for sustainable use of GM crops in IPM
• Pest resistant GM plants must be seen as an
IPM component that can be optimized
Biological
control
Pest Biology
& Ecology
Cultural
control
Cross-
Commodity
AreawideHost plant
resistance
Detection
Sampling & Monitoring
Thresholds
Insecticides
Resistance Manage.
Challenges for research
• How to reduce crop losses (mainly in the developing
world) and what can GM plants contribute to food
security?
• How to integrate GM plants in sustainable
agricultural systems incl. organic agriculture?
• How can new technologies in agriculture get trust by
the public (not only GM plants)?
• Social sciences have to play a stronger role
Outline
• Crop loss and crop protection
• Integrated Pest Management (IPM) - a
sustainable crop protection strategy
• The ideal pest resistant GM plant?
• GM crops, IPM and the landscape
• Resistance management of IR GM crops
• Economics and social aspects
Impact on non-target pests – a meta-
analysisE
ffe
ct
siz
e
-1.6
-1.2
-0.8
-0.4
0.0
0.4
0.8
1.2
140
95
19
7
8
31
Cotton Maize Plant
bugs
Stink
bugs
Aphids Whiteflies
Courtesy of S. Naranjo 2009 Wolfenbarger et al. 2008
IPM and the concern of pest resistance
• Resistance of pests is a general concern in crop protection (>
550 arthropod pests have developed resistance to pesticides)
• Prevention measures are:
a) use of avoidance strategies (e.g. crop rotation,
resistant plants),
b) combining technologies (e.g. resistant plants,
biological control, field sanitation),
c) use of alternating chemical compounds.
Resistance management of Bt crops includes: high
dose/refuge strategy and stacked Bt genes expressing
several Cry types.
ongoing debate of evolved field resistance of Helicoverpa zea
in Bt Cry1Ac cotton (Tabashnik at al. 2008, Moar et al. 2008)
Increasing number of HT crops (with same a.i.) increases risk
of resistant weeds
Biological
control
Pest Biology
& Ecology
Cultural
control
Cross-
Commodity
AreawideHost plant
resistance
Detection
Sampling & Monitoring
Thresholds
Insecticides
Resistance Manage.
Survey of health impact of Bt cotton on
farmers in China
Number of
farmers in
survey
Pesticide
quantity
(kg/ha)
% farmers
reporting
poisoning
Bt cotton only 316 18 9
Bt and non-Bt 61 29 26
Non-Bt cotton
only
30 46 33
Hossein et al. 2004