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Insect dynamics in agriculture can we provide ecological solutions to an ecological challenge?Toby Bruce
High yielding varieties
really ?
Split second decisions
Labandeira (2013) Curr. Opin. Plant Biol. 16: 414400 MILLION years
Toby J. A. Bruce J. Exp. Bot. 2012;63:537-541 The Author [2011]. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved. For Permissions, please e-mail: [email protected] influencing crop protection in an agro-ecosystem
Factors influencing crop protection in an agro-ecosystem. Current trends are making the system more vulnerable to pests, weeds, and diseases, but GM could provide novel resistance traits and increase crop genetic diversity.
Promoting IPM and use of alternatives2009/128/EC on the Sustainable Use of PesticidesReducing risks and impacts of pesticide use on human health and environment
Development of Alternatives is urgently needed
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Development of Alternatives is urgently needed
Why is it needed?
New directions for 21st Century AgricultureRoyal 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?
AgronomyResistant cropsEnhancing BiocontrolImproved targetingRNAi
Information and data sharingImproved targetingIntelligent agricultureCrop protection from pests new directions are needed
Finding prey in natural habitats:
Insects have evolved remarkable sensory abilities
Challenging assumptionsThe nervous system provides a simplified representation of the external environment
but perhaps it is not that simple?
Jeanine Linz et al. Proc. R. Soc. B 2013;280:20130626
Challenging assumptionsInnate responses of insects to odors can be exploited for pest management
but to what extent are responses innate?
should cues be associated with fitness?
https://thelifeofyourtime.wordpress.com/2011/11/13/plant-insect-interaction-parasitoid-wasps-on-goldenrod/
Split second decisions
Insects have sharp spatio-temporal resolution of olfactory signals
How a chemical is perceived depends on space & timeBruce et al. (2005) TRENDS in Plant Science 10: 269
Ratio matters
7ng a-pinene5ng 6-methyl-5-hepten-2-one10ng 3-carene 4ng acetophenone4ng 2-dodecanone7ng a-pinene15ng 6-methyl-5-hepten-2-one10ng 3-carene 4ng acetophenone4ng 2-dodecanone7ng a-pinene10ng 3-carene 4ng acetophenone4ng 2-dodecanone
**
caryophyllenehumulene4-allylanisolecinnamaldehydelinalool(E)-ocimenelimonenemyrcene
Ratio matters
*
A = unbaitedB = 3-comp blend (natural ratio)C = 3-comp blend (1: 1: 1, low)D = 3-comp blend (1: 1: 1, high) Linalool (600ul/thin/100G)17.7mg/dayCinnamyl alcohol (500ul/thin/500G)0.4mg/dayCinnamylaldehyde (300ul/thin/2000G)0.77mg/day
Ratio matters
Attraction!Blend makes a difference
Webster et al. (2010) Animal Behaviour 79: 451
Insects have exquisite spatio-temporal resolution of olfactory signals
Insects have exquisite spatio-temporal resolution of olfactory signalsBruce & Pickett (2011) Phytochem. 72: 1605
Riffell et al. (2013) Science 339: 200-204Adaptability in a changing environmentManduca sexta hawkmoths have innate preference for night blooming flowers like jimsonweed
Adaptability in a changing environment !Switch to Agave palmeri if there is a shortage
Disease influences outcomeVolatiles from Fusarium graminearum infested wheat are repellent to grain aphid, Sitobion avenae
EAG active compounds: 2-pentadecanone, 2-heptanone, phenyl actetic acid, -gurjunene, 2-tridecanone, -cedrene
The Challenge:
Rachel Carson in Silent SpringA truly extraordinary variety of alternatives to the chemical control of insects is available. Some are already in use and have achieved brilliant success. Others are in the stage of laboratory testing. Still others are little more than ideas in the minds of imaginative scientists, waiting for the opportunity to put them to the test. All have this in common: they are biological solutions, based on the understanding of the living organisms they seek to control and of the whole fabric of life to which these organisms belong. Specialists representing various areas of the vast eld of biology are contributingentomologists, pathologists, geneticists, physiologists, biochemists, ecologistsall pouring their knowledge and their creative inspirations into the formation of a new science of biotic controls.
Carson, 1962
OWBM Resistant varietiesFemales lay eggs, but larvae die when they start to feed
A wound plug is formed at the feeding site due to lignification
Resistant varieties
Now approx. 60% of UK wheat is resistant
Bruce et al. (2007) Pest Man. Sci. 63: 49
pheromone traps are now commercially available to wheat growers in the UK
Monitoring systems
Can we do this?repel pests
attract their enemies
Can pest management become symbiotic?From an ecological and evolutionary point of view, perhaps easier to work with beneficial insects than against pest insects?
Biological control of pests - either by release in glasshouses or encouraging natural populations outside.
Aphidius
Aphelinus
Dendrocerus
Alloxysta
Pachyneuron
Asaphes
Praon
4th trophic level pests of the pests of the pests
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BiocontrolProven success in greenhouses with artificial release
Conservation biocontrol strategies needed in outdoor cropping environmentsGrowth rate and arrival rate slower than pestsCan arrival be speeded up?
Conservation biocontrol - preserving what is already out there
1= (E)--ocimene; 2= -terpinolene; 3= -caryophyllene; 4= humulene; 5= (E)-4,8-dimethyl-1,3,7-nonatriene; 6= -cedrene; 7= hexanal; 8= (E)-2-hexenal; 9= (Z)-3-hexen-1-ol; 10= (Z)-3-hexen-1-yl acetate ; 11= 5,7,2,4-tetrahydroxy-6-(3-methylbut-2-enyl)isoflavanone (uncinanone A); 12= 4,5-dihydro-5,2,4-trihydroxy-5-isopropenylfurano-(2,3;7,6)-isoflavanone (uncinanone B); 13= 4,5-dihydro-2-methoxy-5,4-dihydroxy-5-isopropenylfurano-(2,3;7,6)-isoflavanone (uncinanone C), and 14= di-C-glycosylflavone 6-C--L-arabinopyranosyl-8-C--D-glucopyranosylapigenin.
Khan et al. (1997) Nature 388: 631-632Khan et al. (2010) J. Exp. Bot. 61: 4185
Classic example: Effective recruitment of biocontrol in Push-pull
significantly longer time spent on induced plants
0510152025TreatedControlmin
Aphidius ervi foraging on cis-Jasmone treated wheat
Reduction in aphid numbers
Pheromone impact period
Aphid load reduced by half
Aphid load reduced by half
Pheromone impact period
JuneJulyAug
p