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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: journals.permissions@oup.comFactors 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

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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