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New approaches to breeding,
targeting increased pest
resistance
Toby BruceSCI meeting, 15 May 2014
Modern agriculture:
High yielding varieties (?)
High yield –
only if there is adequate crop
protection against pests
Overview of talk:
• Vulnerability of agro-ecosystems to pest attack
Implications for Food Security
• Insect-plant interactions
• Plant genetics for managing pests
• Conclusions
Vulnerability of agro-ecosystems to
pest attack
Lush monocultures of high yielding varieties grown with fertiliser and irrigation are often more susceptible to pests
Bruce (2011) J. Exp. Bot. 63: 537-541
fewer effective
pesticides
legislation
reduced discovery
and approval of new
products
rapid evolution
and spread of resistant
biotypes
short generation
time
high reproductive
rate
easy dispersal
global trade
consumer demand to
replace pesticides
fewer effective
pesticides
reduced genetic diversity in crops
THRIVING PESTS AND HIGH CROP
LOSSES
climate change can make conditions better for pests
less intrinsic resistance to insects and
pathogens, and less competitiveness with
weeds
fertilised crops more nutritious to insects
and pathogens
broad spectrum pesticides kill
natural enemies of pests
Bruce (2011) J. Exp. Bot. 63: 537-541
Impact of Pests, Weeds & Diseases
1965 – staple cereals
1992 – staple cereals
42%
lost
36%
lost
SOURCE: Oerke & Dehne (2004) Crop Prot 23:275–285
Crop losses caused by pests have not decreased since the
1960s, even with use of pesticides
Resistance to agrochemicals worldwide
EC Directive 2009-128
A framework “Promoting the use of IPM and of alternative approaches”
Research on “Alternatives” is urgently needed
Promoting
IPM and use
of
alternatives
2009/128/EC on the
Sustainable Use of Pesticides
Reducing risks
and impacts of
pesticide use on
human health
and environment
Research on “Alternatives” is urgently needed
“Impacts of pesticides on human
health and the environment”
… BUT WAIT, some impacts are positive
Human health
► increased affordability of
healthy food (e.g. fruit &
veg)
► less mycotoxin
contamination
Environment
► more food can be
produced on less land
with less water and
fertiliser
► more efficient production
– less GHG
• EU yields decline
• Increased selection pressure for resistance to
remaining pesticides
• Food price increase
• Food production companies move out of Europe
• More land used for agriculture
Unintended consequences
0
1000000
2000000
3000000
4000000
5000000
6000000
7000000
8000000
9000000
10000000
1961 1966 1971 1976 1981 1986 1991 1996 2001 2006 2011 2016 2021 2026 2031 2036 2041 2046
Po
pu
lati
on
(10
00
s);
Ce
re
al
Pr
od
uc
tio
n (
x 5
00
to
nn
es
)
Will future demand be met?
Source: FAOSTAT
Bruce (2010) Food Security 2: 133-141
To keep pace with
growing demand,
global food
production needs
to increase by an
estimated 70% by
2050 [United
Nations]
New directions for Agriculture in the 21st
Century
Royal Society: “There is a pressing
need for the ‘sustainable
intensification’ of global agriculture in
which yields are increased without
adverse environmental impact and
without the cultivation of more land”.
Royal Society (2009) Policy document 11/09
A second green revolution which is knowledge intensive rather than input intensive?
So we need to new ways to control
pests…
…there are opportunities via plant breeding
Insect-plant interactions
The different timescales associated
with insect-plant interactions
Bruce (2014) JXB in press
DNA code has evolved over millions of years - subject to mutations that are deleterious or advantageous according to context
- gene expression is modulated by epigenetic ‘stress imprints’
Insect effectors supress or induce
plant defence (depending if insect or plant is
‘ahead’)
(image courtesy of Saskia Hogenhout)
Plant defence changes over time
(image courtesy of Jurriaan Ton and Marieke van Hulten)
Host location: Rapid decisions by insects about
plant colonisation, made in flight
Bruce (2014) JXB in press; Bruce et al. (2005) TRENDS in Plant Science 10: 269
Insect responses change over time
(image courtesy of Patrizia d'Ettorre and Mauro Patricelli)
Plant genetics for managing pests
ORANGE WHEAT BLOSSOM MIDGE
Orange wheat blossom midge
• varies from year to
year
• was difficult to decide
in time which fields
needed treating
• difficult to control with
insecticide
• Females lay eggs, but
larvae die when they start
to feed
• A wound plug is formed at
the feeding site due to
lignification
Resistant varieties
Resistant varieties
Oakley et al 2005 HGCA Project Report No. 363
Resistance found in ‘Welford’ - 2004
Now approx. 60% of UK wheat is resistant
Dam
age s
core
Monitoring systems: sex pheromone traps
Bruce et al. (2007) Pest Man. Sci. 63: 49
• Allow rational use of pesticides
• Need based applications save
costs and importantly slow
down the development of
resistance
• sex pheromone traps:
- provide a solution to the
detection problem
- enable more accurate and
effective spray timing
OCOC3H7
OCOC3H7
Decision support system for OWBM
Bruce & Smart (2009) Outlooks Pest Management 20: 89-92
Yellow rust on wheat OWBM resistant cultivar (Robigus)
Need for multiple resistance
CIS-JASMONE
Bruce et al. (2003) Pest Management Science 59: 1031 – 1036
Field plot trial: spray applicationO
0
0.2
0.4
0.6
0.8
1
1.2
28-May 8-Jun 16-Jun 24-Jun 6-Jul
Me
an
No
. A
ph
ids
/ T
ille
r
*
*
control
cis-jasmone
P = 0.036
Bruce et al. (2003) Pest Management Science 59: 1031 – 1036
Wheat Field Trial
Response to cis-jasmone: Solstice >
Consort > Hereward > Welford
3. Hereward
0
50
100
150
200
250
01-Jun 7 12 20 29 06-Jul
tota
l a
ph
ids
/40
0 t
ille
rs
control
CJ
4. Welford
0
20
40
60
80
100
120
140
160
180
200
01-Jun 7 12 20 29 06-Jul
tota
l a
ph
ids
/40
0 t
ille
rs
control
CJ
1. Solstice
0
50
100
150
200
250
300
350
01-Jun 7 12 20 29 06-Jul
tota
l a
ph
ids
/40
0 t
ille
rs
control
CJ
2. Consort
0
20
40
60
80
100
120
140
160
01-Jun 7 12 20 29 06-Jul
tota
l a
ph
ids
/40
0 t
ille
rs
control
CJ
significantly longer time spent on
induced plants
0
5
10
15
20
25
Treated Control
min
Aphidius ervi foraging on cis-Jasmone
treated wheat
Pest Management
repel pests
attract their enemies
GM WHEAT EMITING APHID ALARM PHEROMONE
1 6 . 0 0 1 8 . 0 0 2 0 . 0 0 2 2 . 0 0 2 4 . 0 0 2 6 . 0 0 2 8 . 0 0 3 0 . 0 0 3 2 . 0 0 3 4 . 0 0 3 6 . 0 0 3 8 . 0 0
5 0 0 0 0 0
1 0 0 0 0 0 0
1 5 0 0 0 0 0
2 0 0 0 0 0 0
2 5 0 0 0 0 0
3 0 0 0 0 0 0
3 5 0 0 0 0 0
4 0 0 0 0 0 0
4 5 0 0 0 0 0
T i m e - - >
A b u n d a n c e
T I C : 1 0 - 0 0 0 6 1 . D
1 6 . 0 0 1 8 . 0 0 2 0 . 0 0 2 2 . 0 0 2 4 . 0 0 2 6 . 0 0 2 8 . 0 0 3 0 . 0 0 3 2 . 0 0 3 4 . 0 0 3 6 . 0 0 3 8 . 0 0
5 0 0 0 0 0
1 0 0 0 0 0 0
1 5 0 0 0 0 0
2 0 0 0 0 0 0
2 5 0 0 0 0 0
3 0 0 0 0 0 0
3 5 0 0 0 0 0
4 0 0 0 0 0 0
4 5 0 0 0 0 0
T i m e - - >
A b u n d a n c e
T I C : 1 0 - 0 0 0 1 1 . D
4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0 1 4 0 1 5 0 1 6 0 1 7 0 1 8 0 1 9 0 2 0 0 2 1 00
5 0 0 0 0
1 0 0 0 0 0
1 5 0 0 0 0
2 0 0 0 0 0
2 5 0 0 0 0
3 0 0 0 0 0
3 5 0 0 0 0
4 0 0 0 0 0
4 5 0 0 0 0
5 0 0 0 0 0
5 5 0 0 0 0
m / z - - >
A b u n d a n c e
A v e r a g e o f 2 5 . 6 1 9 t o 2 5 . 6 4 8 m i n . : 1 0 - 0 0 0 6 1 . D6 9
9 3
4 1
1 3 3
7 91 2 0
1 6 1
5 5
1 0 7
2 0 4
1 4 8 1 8 91 7 5
transgenic line
wild type
Wheat transformed with targeted synthase gene
emits (E)-ß-farnesene
Aphids repelled by volatiles of transformed wheat
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Tim
e (
min
s)
Rhopalosiphum padi
0
1
2
3
4
5
Tim
e (
min
s)
Sitobion avenae
P = 0.010P < 0.001
treated treatedcontrol control
Parasitoid wasps spend longer foraging
on transformed plants
0
100
200
300
400
500
600
700
800
B2803 B2812 CADENZA
Tim
e (
se
c)
*
transgenic lines wild type
Field trial
Field trial
RESISTANCE FROM WILD RELATIVES
Resistance to insect pests
Gia Aradottir, Janet Martin and Lesley Smart
Screening wheat lines
against cereal aphids
• >500 lines tested on both
aphid species
▫ Watkins Core Collection plus
~150 extra lines
▫ Gediflux Collection 63 lines
▫ Aegilops speltoides
▫ Triticum monococcum
▫ CIMMYT Synthetic x Paragon
▫ W141 x Paragon mapping
population
0
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
0 50 100 150 200 250 300
g
number of lines
Sitobion avenae nymph weight after 7 days
Ae. speltoides
T. monococcum
NIAB CIMMYT SxPar
Watkins
Gediflux
Paragon
Solstice
tetraploids
W141xPar
0
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0 50 100 150 200 250 300
g
number of lines
Rhopalosiphum padi nymph weight after 7 days
Ae. speltoides
T. monococcum
NIAB CIMMYT SxPar
Watkins
Gediflux
Paragon
Solstice
tetraploids
W141xPar
Introgressing resistance?
at least 10,000 years ago
wild einkorn wheat (Triticum urartu)
wild goat grass related to Aegilopsspeltoides
Triticum diccocoides, wild emmer wheat
prehistoric times
goat grass (Aegilopstauschii)
Bread wheat, Triticumaestivum
Blight resistant potato +Rpi-vnt1
5 fungicide sprays to protect
No pesticide needed
(image courtesy of Jonathan Jones)
• 10 wild potato lines tested for
resistance to Myzus persicae and
Macrosiphum euphorbiae
• 10 plants of each line were grown and
5 aphids were placed in a clip cage on
each plant in a no choice test
• Two lines had high resistance with 0%
aphid survival after 7 days
Aphid resistance in
wild potato
Aphid resistant wild potatoes
0102030405060708090
100% Nymph
survival(after 7 days)
0
2
4
6
8
10
12 Nymphs produced
(after 24h)
00.5
11.5
22.5
33.5
44.5
5Adults settled
(after 24h)
Two of the ten lines tested were very
resistant with 0% aphid survival after 7 days.
EGG ALERT
Stemborers
(E)-caryophyllene
(E)-4,8-dimethyl-1,3,7-nonatriene
Collecting volatiles from plants with
eggs
Bioassay
• insect released in the centre
• time spent in treated arm compared
with time spent in control arms
Response to volatiles collected from plants with and
without eggs?
Maize landrace lines
Tamiru et al. (2011) Ecology Letters 14: 1075
Parasitoid response - landraces
Attracted to plants with eggs
Volatile profiles - landraces
(a) (E)-ocimene, (b) (R)-linalool, (c) (E)-4,8-dimethyl-1,3,7, nonatriene (DMNT), (d) methyl salicylate, (e) decanal, (f) methyleugenol, (g) (E)-(1R,9S)-caryophyllene, (h) (E)-β-farnesene, (i) (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT).
Tamiru et al. (2011) Ecology Letters 14: 1075
Diverse seeds
HIPV induced by eggs in improved line
Improved maize line CKIR12001 emits DMNT when
stemborer eggs are laid on it.
Conclusion
Intensified agriculture is more
dependent on crop protection
Lush monocultures of high yielding varieties grown with fertiliser are often more susceptible to pests
Value of Crop Protection – UK wheat
Oerke EC (2006) Crop losses to pests. The Journal of Agricultural Science 144:31-43.
Value of UK wheat production in 2011
(Defra - Agiculture in the UK dataset) £ 2 210 million
Crop losses with no crop protection
(from Oerke 2006) %
weeds 23 £ 508 million
pests 8.7 £ 192 million
diseases 18.1 £ 400 million
TOTAL £1100 million
Lesley Smart
Janet Martin
Christine Woodcock
Keith Chamberlain
Barry Pye
Michaela Matthes
Ian Prosser
Mike Birkett
Abdul Mohib
John Pickett
Johnathan Napier
Lester Wadhams
Emma Smith
Carol Moraes
Questions… ?
