resistance is futile inevitable: integrated pest in

Rothamsted Researchwhere knowledge grows

Resistance is futile inevitable: Integrated Pest Management in oilseed rape is a need ‐ not an

option

Sam CookRothamsted Research, UK

One of the biggest challenges of our time?

Insecticide resistance ‘could make growing oilseed rape impossible’

What are the insect pests of oilseed rape?

How does the crop survive?!

What do growers do to protect yield?

Over‐reliance of insecticides for control of insect pests in OSR

Kill the pests with the cheapest available insecticide! ‐ usually pyrethroid spray(s)

‐ Since 1990’s neonicotinoid seed treatments (for autumn pests)

Resistance is inevitable

• Synthetic organic insecticides in the 1940’s• First cases of resistance detected 1947• With every new insecticide introduction… cyclodienes, organophosphates,

carbamates, formamidines, pyrethroids, Bacillus thuringiensis, spinosyns and neonicotinoids…. cases of resistance in key pests occurred 2 ‐ 20 years after their introduction

Sodiumchannels

Ach

Na +

nAChR

Cl channel

GABA

AxonNerve impulse

AChE

Mechanisms of insecticide resistance

target site resistance

P450 GSTCCE

metabolic resistance

Insecticide

Courtesy of Dr Martin Williamson , Rothamsted Research

Insecticide resistance in Peach‐potato aphid (Myzus persicae)

Damage

• Feeding damage by adults and nymphs economically minor

• Virus vector – Turnip yellows virus (TuYV)• Can reduce yield by c. 30% • C. 70% of UK Myzus population infected

• Resistance to pyrethroids widespread in UK; also resistance to pirimicarb

• Pymetrozine only viable alternative in UK (timing critical)

Dewar Crop Protection

Insecticide resistance inPollen beetle (Meligethes/Brassicogethes aeneus)

Damage

• Adult feeding damage at bud stage causes abscission ‘blind stalks’

Untreated vs. treated

Pyrethroid resistance in pollen beetle

• 1st recorded in France 1999• Resistance widespread across mainland Europe• 1st recorded in UK 2006 (Kent)• HGCA information factsheet 12/2011

• Now widespread across UK incl. Scotland

• Since c. 2013: Indoxacarb, neonicotinoids (thiacloprid acetamiprid) & Pymetrozinecurrently viable alternatives……

Insecticide resistance in Cabbage stem flea beetle (Psylliodes chrysocephala)

• Adult feeding damage may threaten establishment (100% crop loss)

• Controlled by pyrethroids to 1990s then neonicotinoid seed treatments

• Historically, larval damage more serious• Larvae cause loss of vigour, stem wilting,

delayed flowering, stem collapse; increased risk to frost and disease

• Controlled by pyrethroid sprays

Damage

Dewar Crop Protection

Pyrethroid resistance in Cabbage Stem Flea Beetle

• On 1/12/13 a 2‐year restriction on the use of the neonicotinoids: clothianidin, imidacloprid and thiamethoxam, was enforced by the European Commission.

• The 2014 winter crop was the first for which neonicotinoid seed treatments were not available to protect plants during emergence and establishment


• In autumn 2014 Pyrethroid sprays become the main (only?) control option for adults AND larvae….

• BUT pyrethroid resistance confirmed in Germany Zimmer et al., 2014 PBP 108:1‐7


• In autumn 2014 Pyrethroid sprays become the main (only?) control option….

• BUT pyrethroid resistance confirmed in Germany Zimmer et al., 2014 PBP 108:1‐7

• …and widespread in UK (Sept 2014) AHDB Project 214–0019 Courtesy of Dr Steve Foster Rothamsted Research

Cabbage stem flea beetle (Psylliodes chrysocephala)

What happened in 2014?


• Pyrethroids were repeatedly applied!


Crop sprayed: 3x vs 6x


• Pyrethroids were repeatedly applied!..... What effect on the non‐targets? this needs to be quantified urgently!


Crop sprayed: 3x vs 6x


What happened in 2014?Significant crop losses (regional; S, SE) – Growers giving up growing OSR

Growers giving up OSR is bad news for biodiversity!

Skellern & Cook in prep

Oilseed rape crops support populations of bees, butterflies & other pollinators, natural enemies of crop pests, detritivores & invertebrates used as food resources for farmland birds

British Ornithologists Union

Integrated Pest Management (IPM) of insect pests in OSR is a need not an option!

• Resistance management via use of >1 active is not an option for most pests of OSR ; there aren’t enough actives… if any!

• Full IPM strategies needed to reduce further selection for insecticide resistance and provide alternatives for control

Integrated Pest Management (IPM) of insect pests in OSR is a need not an option!

• IPM is an effective and environmentally sensitive approach to pest management that relies on a combination practices (including the judicious use of pesticides)

• 4 usual steps in IPM programmes:1. Set action threshold2. Monitor pest density & assess risk3. Prevention – cultural methods e.g. crop rotation, use of pest‐

resistant cultivars, semiochemical e.g. pheromone repellents, habitat diversification intercropping, trap cropping

4. Control – mechanical (e.g. trapping), biological, conservation biocontrol, botanical insecticides, synthetic pesticides

1. Set Action Thresholds

Action thresholds refer to the number of pests or level of pest damage above which require control measures.

Based on:Pest biologyEffects of damage on yieldResponse of pests to insecticides

Expressed as:Number of pests per plant or per unit area of crop Amount of damage seen on plants

1. Set Action Thresholds

• Defined for each pest species (but few supported recent research!)Pest UK threshold

CSFB Emergence: No threshold!Coteleydon‐ 2 leaf stage: >25% of leaf area eaten3‐4 leaf stage: >50% of leaf area eatenOR if the crop us growing more slowly than it is being destroyed

5 larvae /plant

Peach‐potato aphid As soon as detected in crop

pollen beetle Varies with plant density (average c. 15 adults / plant)<30 plants/m2 = 25 beetles/plant30‐50 plants/m2 = 18 beetles/plant50‐70 plants/m2 = 11 beetles/plant>70 plants/m2 = 7 beetles/plant

Cabbage seed weevil 0.5 adults/plant in north; 1/plant elsewhere

Pod midge Treat for cabbage seed weevil

2. Monitor pest density & assess risk

• Monitoring is necessary to determine the level of pest infestation and/or damage

• Informs when control threshold for a pest has been reached

• Helps to assess efficacy of control measures

• Methods based on understanding of pest life cycle, phenology, crop location behaviour, immigration behaviours and spatio‐temporal distributions


Monitoring ‐ adult pest aphidsSuction traps


Monitoring methods – adult pest counts

• Count adult pests on plants (pollen beetle)‐ Plant beating 10 plants along 30m transect when >15˚C


Making monitoring easier: Pollen beetle trap

‐ Developed at RRes through understanding of host plant location processes (colour & odour)

‐Should be placed downwind of prevailing wind

‐ Provides good understanding of when beetles are moving locally

• Needs calibrating to relate numbers in crop to numbers on trap

Available commercially from Oecos www.oecos.com

VOLUNTEERS NEEDED!

If you have an OSR field close to home/office/dog walking route…

…and can monitor traps & perform a transect at least 3/week

Please get in touch! [email protected]

All materials provided!

Special need of sites in Scotland, Wales, Cornwall/Devon, North‐East & North‐west!

AHDB Project 214005 Validating an IPM strategy for pollen beetles in OSR


Monitoring methods: CSFB – adult damage

• Assess % feeding damage to leaves


Monitoring methods : CSFB – larval damage

• Count larvae in plant petioles and stems (from at least 25 plants/field) ; threshold = average 5/plant

• Count stem/petiole damage; >50% relates to c. 2‐5 larvae/plant

Dewar crop protection


Monitoring methods : CSFB – larval damage

• Water traps (4/field)• 2 in headland and 2 in‐field • Threshold: mean total>96/trap over period Sept. to end Oct. • But timing of larval sprays critical; this measure is rather crude• Where best to trap?

Warner et al., (2003) Ent. Exp. Appl. 109:225‐234


ProPlantexpert.com on‐line risk assessment tool for: Cabbage stem flea beetle, rape stem weevil, pollen beetle, cabbage stem weevil, cabbage seed weevil, brassica pod midge

• proPlant DSS developed in Germany, used widely in Europe• Based on phenological models of pest immigration and life cycle

development parameters • Uses local weather conditions (temperature, sunshine h,

windspeed & rainfall) • Predicts pest parameters up to 3d in advance• Uses traffic light warning system


• Trapping data from 178 crops across UK over 4 years • proPlant can accurately forecast start, peaks (risk periods) and end of immigration; • Focussing monitoring effort to when it is most needed, reducing it by half cf. rule based

advice

Ferguson et al.& Cook , (2016) Pest Management Science 72:609‐617


ProPlant tool now available free to UK growers via Bayer Pollen Beetle Predictor www.bayercropscience.co.uk/

Ferguson et al., accepted Pest Management Science

Improved risk assessment for CSFB IPM

ProPlantexpert.com On‐line risk assessment tool

1. Indicates start & end of adult migration and highlights risk of migration

2. Warns of start of egg laying, intensity & larval development predictions

Low risk (moderate conditions) Treatment against adults to prevent egg laying still possible

Risk medium (good conditions) Treat later against larval hatching

Risk high (optimal conditions)Risk of high proportion of larvae hatching before winter. Important to monitor plants for larval symptoms

Improved risk assessment for CSFB IPM

ProPlant expert.com On‐line risk assessment toolValidating the proPlant phenological model for CSFB under UK conditions 3 field seasons: 2013‐2016

Preliminary results

1. Earlier migration in UK

2. 2015 larvae found very early (9th Oct!) – way before spray based on adults in traps would have been applied‐ Accurately forecasted by proPlant!

3. Larval development forecasts could help to time spray applications… (if we have any actives!)

3. Prevention

Cultural methods e.g. • Crop rotation• Use of pest‐resistant cultivars• Habitat diversification : intercropping, cover crops,

mixed cropping, trap cropping

Semiochemical e.g. • pheromone repellents

3. Prevention: Use of pest resistant cultivars

Resistant cultivars available for diseases (Light leaf spot, Stem canker)

No commercial cultivars resistant to any insect pest!


Exciting genetic breakthrough by Limagrain:

cv. Amelie ‐ resistant to TuYVtransmitted by Myzus persicae

• Important IPM tactic ; timely given ban on neonicotinoid seed treatments and resistance in aphids to pyrethroids


Exciting genetic breakthrough by Limagrain:

cv. Amelie ‐ resistant to TuYVtransmitted by Myzus persicae

• But resistance based on virus not against the host insect• Plant resistance to insect pests still in research pipeline

3. Prevention

Development of preventative methods (and alternative control options) often relies on understanding (then disruption) of host‐plant location and selection processes

Visual cues e.g. plant colour

Williams & Cook (2010) in Biocontrol –based IPM of oilseed rape pests

3. Prevention


Olfactory cues e.g. plant volatiles

3. Prevention


Gustatory cuesglucosinolates ? (specific defence compounds found in all Brassicaceae)


Pollen beetle Visual cues

• Attracted to ‘yellow’; Cultivars with petal colour other than yellow would be less attractive! Cook et al (2013) Arthropod‐Plant Interactions 7:249–258


Pollen beetle Olfactory cues

• Attracted to host plant volatiles including isothiocyanates (breakdown products of glucosinolates)

Cultivars which produce lower amounts of ITC are less attractive to pollen beetle

low % alkenyl GS high % alkenyl GS

Cook et al (2006) Ent. Exp. Appl. 119:221‐9


Pollen beetle Gustatory cues

Hervé et al (2014) J Chem Ecol 40:1220‐1231; 2014 APIS 8:383‐392

• Variation in feeding damage between cv • + relationship with sucrose in bud wall

(no relationship with glucosinolate profile)


Breeding pest resistant/tolerant traits into OSR

• Resynthesised lines?

B. oleracea × B. rapa partial resistance to Ceutorhynchspallidactylus Eickermann et al J. Appl Ent. (2010) 134:542‐550; Bull. Ent. Res 101:287‐294

B. napus x S. alba resistance to Ceutorhynchus obstrictusMcCaffrey et al. (1999) J. Ag Sci. 132 289‐295Tansey, Dosdall et al (2010) Canadian Entomologist 142:212‐221; APIS 4:95‐106

3. Prevention: Habitat diversification (intercropping, cover crops, mixed cropping, trap cropping)

Turnip rape (Brassica rapa)More attractive than OSR for pollen beetles and seed weevils

Turnip rape trap crops can reduce populations to below spray thresholdCook et al., 2006; Ent. Exp. Appl. 119:221‐9

Cook et al., 2007 Arthropod‐Plant Interactions 1:57‐67

… But cost:benefit analysis at full field scale revealed current system NOT currently economically viable for conventional growers (UK)


Cook et al (in prep)


• Turnip rape (Brassica rapa) is more attractive than OSR to CSFB Barari, Cook, Clark & Williams (2005) BioConrol 50: 69‐86Döring, Mennerich & Ulber (2014) Bulletin IOBC/wprs

• In field plot experiments (2005), TR borders significantly reduced no. CSFB in main OSR crop vs controls

Barari, Cook, Clark & Williams (2005) BioConrol 50: 69‐86

Plot centres Plot borders


• PhD studentship Duncan Coston ‘’Quantifying the impacts of the Neonicotinoid restriction on Oilseed Rape’’ Supervised by RRes (Sam Cook, Lin Field) & University of Reading (Tom Breeze & Simon Potts)

• Initial results looked promising but by Christmas ALL OSR plants were gone


• Work from France shows that intercropping or undersowing OSR with legume mixtures can reduce CSFB infestation

• Farmers are trying this in UK because they are desperate!• Researchers must co‐innovate; reduce the risk taken by farmers by

providing science behind the claims!• NIAB trial comparing 4 cover crop mixtures on CSFB damage


• Work from France shows that intercropping or undersowing OSR with legume mixtures can reduce CSFB infestation

• Farmers are trying this in UK because they are desperate!• Researchers must take the risk from farmers by providing science

behind the claims!• NIAB trial comparing 4 cover crop mixtures on CSFB damage

• Initial results looked promising but by January most OSR plants were gone

3. Prevention: Use of semiochemicals

• Non‐host volatiles as repellents e.g. Lavendula angustifoliaEssential oil

Mauchline et al., 2005. Ent. Exp. Appl 114: 181‐188.Mauchline, Cook, Powell & Osborne (2013) Ent. Exp. Appl 146:313‐320. Mauchline & Cook in prep

3. Prevention: Use of semiochemicals

• Pheromones• Evidence for production of sex pheromone (Bartlet et al (1994) Phys. Ent. 19: 241–250)• Looking again (2015‐16): Vutz, Birkett & Cook (RRes)

4. Control: Mechanical trapping

http://www.csalomontraps.com/

Mechanical e.g. trapping

Mass trapping kit for pollen beetles commercializedProbably not practical in OSR due to sheer abundance of pests?

4. Control

• Mechanical e.g. trapping

• Botanical insecticides

• Rock dusts

• GM

• RNAi’s

• Conservation biocontrol

• Synthetic insecticide spays as a last resort

} in research pipeline

4. Control: Conservation biocontrol

Use of agronomy & habitat management methods to conserve the natural enemies of crop pests in the agro‐environment to improve biocontrol

• Field margins can support populations of natural enemies of crop pests

• Commercial mixtures for birds, bees/butterflies but none for biocontrol!


Designing field margins for biodiversity & biocontrol across the crop rotation www.rothamsted.ac.uk/field‐margins

• Grassy margins support generalist natural enemies of aphidse.g. Holland et al., 2012 Ag. Ecosyt. Env. 155:147‐152

• Nectar‐rich mixtures can attract other generalists


Designing field margins for biodiversity & biocontrol across the crop rotation www.rothamsted.ac.uk/field‐margins

Most efficient natural enemies of the brassica specialist pests of OSR are the brassica specialist parasitoids • Parasitism rates up to 80% in untreated crops• Many overwinter as cocoons in soil; susceptible to tillage

• Undisturbed field margins could boost populations• But they need Brassicas to reproduce and most commercial

mixtures do not contain brassicas!


Forage rape ‘banker plants’ for use in field margins for biocontrol across the crop rotation

14 Brassica types screenedBrassica napus subsp. Biennis Forage rapebest ‘all‐rounder’ ‐ Good for parasitoids of:

Pollen beetle

Seed weevil

Pod midge


Do margins containing brassicas improve biocontrol in crops of the rotation?

• Abundance of biocontrol agents was increased in margins

• Abundance decreased with distance into the field

• Little evidence of signficant biocontrol effects

• Challenge for future:‐move biocontrol agents into the open field‐show positive effects on yield

Conclusions

• Oilseed rape crops are great for invertebrate biodiversity

• IPM tools are available for monitoring and risk assessment• IPM tools for prevention and alternatives for control still have

some way to go!

1. Set action threshold2. Monitor pest density & assess risk3. Prevention 4. Control

Further development of ecological approaches to IPM of OSR pests will ensure insecticides are used only when necessary; prolonging their active life, safeguarding the environment, maximising profitibility & contributing towards sustainable intensification of the crop

Acknowledgements

Rothamsted Researchwhere knowledge grows

Project partnersRothamsted ColleaguesJohn PickettIngrid WilliamsMatthew SkellernAndrew FergusonNigel WattsLesley SmartChristine WoodcockJanet MartinLucy Nevard Judith Pell (JK Pell Consulting)

Thank you for listening!

resistance is futile inevitable: integrated pest in

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