Considerations for appropriate assessment of efficacy of biopesticides in the field

The OECD Seminar on Different aspects of efficacy evaluation of biopesticides, held on 28-29 June 2021, covered the similarities and differences of the efficacy evaluation of the different categories of biopesticides, new application techniques, efficacy evaluation of biopesticides based on plant defence inducers (PDI), comparison of efficacy requirements for biostimulants vs. biopesticides, how to evaluate different Integrated Pest Management (IPM) modules, and registration pathways with limited or no evaluation of efficacy. The event facilitated exchanges between policy makers, academia, and industry.

1. Stakeholder’s Experience and Perspective:
Considerations for appropriate assessment
of efficacy of biopesticides in the field
11
th
OECD Expert Group on BioPesticides
Seminar on “Different aspects of efficacy evaluation of biopesticides"
Edith Ladurner
Senior R& D Specialist
CBC (Europe) –BIOGARD Division
Denise Manker
Senior Science Fellow, Biologics
Bayer Crop Science

2. PolicydiscussionsinOECDcountriesareleadingtomoredemandforbioprotectantproducts.
Thiswillrequire:
•ConsistentadoptionofEPPOguidancebyOECDmembercountries
•Flexibilityinefficacyprotocols,includingintheareasof
•ModeofActionsconsiderationforEfficacytrials(appropriatetimingapplications,etc.)
•Appropriatestandardsforcomparison(UntreatedControl,referenceproduct,
referencestrategy,etc.)
•EfficacyevaluationwithinIntegratedprograms,asbioprotectantswillbeusedin
practice
11th OECD Expert Group on BioPesticidesSeminar2

3. Consistent adoption of EPPO guidance by OECD member countries
•SeveralgeneralEPPOstandards,supportingregulatory
authoritiesintheirconsiderationofefficacydataofbioprotectants
(andnotonly),alreadyexist.
•ThisEPPOguidanceshouldbeutilizedbyregulatoryauthoritiesin
theirregulatoryreview.
•SomeOECDmembercountrieshavealreadytakenonboardthe
principlesoutlinedintheEPPOguidance,butthereisaneedfor
thisguidancetoberoutinelyreflectedinregulatorydecisions.
•MostspecificEPPOstandardshavebeendevelopedfor
conventionalchemicalpesticides.
•DuetotheirModeofActions,bioprotectantsneedmoreflexibility
inefficacytestprotocoldevelopmentandtrialset-upinorderto
appropriatelydemonstrateefficacyandvalueinsustainable
practices.
EPPO PP1/276(1)
Principlesfor efficacyevaluationof
microbialplantprotectionproducts
EPPO PP 1/296(1)
Principles of efficacy evaluation for
low-risk plant protection products
EPPO PP 1/214(4)
Principles of acceptable efficacy
11th OECD Expert Group on BioPesticidesSeminar3

4. Consistent adoption of EPPO guidance by OECD member countries
Adoption of EPPO PP1/214(4) Principles of acceptable efficacy:
Balance between direct effectiveness & indirect positive effects
Root-knot nematodes on vegetables
11th OECD Expert Group on BioPesticidesSeminar4
Direct efficacy:
Root Galling Severity (Zeck’sscale: 0 –10)
over time (transplanting –harvest)
Indirect positive effect:
Total Yield (kg/plant, plot or ha)
= total amount of fruits harvested over time
RGS = 4
RGS = 8

5. Consistent adoption of EPPO guidance by OECD member countries
Adoption of EPPO PP1/214(4) Principles of acceptable efficacy:
Balance between direct effectiveness & indirect positive effects
Bioprotectant: garlic extract
Root Galling Severity at end of crop cycle & Total Yield
11th OECD Expert Group on BioPesticides Seminar5

6. ModeofActions:BeauveriabassianastrainATCC74040
•Primarymodeofactionagainstmosttargets:typicalcontactactionofan
entomopathogenicfungus
•PrimarymodeofactionagainstTephritidflies(e.g.Ceratitiscapitata):
ovipositiondeterrentactivityduetohydrophobinsonconidiacreatinga
hydrophobiclayeronfruitsurface.
Significantreductioninnumberofvisits,ovipositionpuncturesandeggslaid
ontreatedfruitscanbeachieved,butrequires:
•Appropriatetimingofapplications(beforefruitfliesstartlayingeggs)
•Appropriateapplicationintervals(7-10days)
•Adequatenumberofapplications(dependingontargetspecies)
Mode of Actions consideration for efficacy trials
11th OECD Expert Group on BioPesticidesSeminar6

7. Modeofactions:BeauveriabassianastrainATCC74040
•consistentand significant reduction in fruit damage compared to UTC, but efficacy depends on pest pressure
•high number of applications acceptable for authorization, but not feasible in practice
UntreatedControl BbATCC 74040
Efficacy
Mode of Actions consideration for efficacy trials
11th OECD Expert Group on BioPesticides Seminar7

8. •Demonstrationofminimumeffectivedosemaybeappropriatefor
conventionalchemicalpesticides
•Bioprotectants,inparticularMicrobialPestControlAgents
(MPCAs),areknowntohavedifferentdoseresponsecurves(non-
sigmoidalorother,ifany)
•TheeffectofMPCAsisrelatedtoinfectivity,pathogenicity,
antagonism,etc.,makingdose-responsecurvesaninvalid
indicator
•ExcessivelyhighratesornumberofapplicationsofB.
amyloliquefaciens/subtilisstrainsmayevenresultinreduced
diseasecontrol
•Appropriatetimingofapplicationsforsuccessfulandtimely
establishmentoftheMPCAonplantpartsthatmustbeprotected,
maybemuchmoreimportant
Mode of Actions consideration for efficacy trials
MPCA
Efficacy
(%)
Appliedrate
ConventionalPPP
Lag
Time
N.
viable
cells
LogStationaryDecline
Phase
surfactins
fengystatins
iturins
11th OECD Expert Group on BioPesticidesSeminar8

9. Comparison to UTC in absence of standard: Alternaria alternata(Black heart) on pomegranate
Appropriate standards for comparison
•Recentstrongincreaseinareacultivatedwithpomegranatein
MediterraneancountriesandconsequentlylimitednumberofPPPs
authorizedforuseonthecrop
•SymptomsofBlackheart:internalblackrotofarilsandmembranes
•SporesofA.alternataentertheflowersduringthefloweringperiodand
startinfection
•Veryhazardousdiseaseonpomegranate,causingproductionlossesof
upto30%
•Tothebestofourknowledge,noreferenceproductcurrently
authorizedagainstBlackrotonpomegranateinconcernedEU
MemberStates
11th OECD Expert Group on BioPesticides Seminar9

10. Comparison to UTC in absence of standard: Alternaria alternata(Black heart) on pomegranate
•Standardusedinthetrialsauthorizedon
pomegranateagainstBotrytiscinereawith
emergencyuseauthorizationthepreviousyear,
butnottheyearthetrialswereperformed.
•Modeofactiondiffersfromthatofbioprotectant
BacillusamyloliquefaciensstrainD747.
•CropdestructionmandatoryalsoforStandard
withoutanyguaranteeofacceptableefficacy.
•ComparisontoUTCshouldbeconsidered
acceptable.
Appropriate standards for comparison
11th OECD Expert Group on BioPesticidesSeminar10

11. Reference product vs. reference strategy: woolly apple aphid (Eriosiomalanigerum) on apple
Woollyappleaphid:
8 or more
generations per year
Migration of aphidsonto
new shootsin spring
Overwinteringaphidson roots and underneathbark
Aphelinusmali overwintersin parasitzedaphids
Parasitized
coloniesregain
activity
Winterapplications
Late-summer
applications
Appropriate standards for comparison
Delayedemergence
of A. mali from
diapause
11

12. “The reference product should be a product known to be satisfactory in practice and,
preferably, with a mode of action the same as or similar to that of the test product.”
•Woollyappleaphid:usuallymajorpestonlyinOrganicFarming
•NoreferenceproductavailableinOrganicFarmingforspring-summerapplicationsexceptfor
bioprotectantsbasedonFattyacidsC7-C18andC18unsaturatedpotassiumsalts
•NoreferencewithsimilarmodeofactionavailableinOrganicFarmingorIPM(testedbioprotectant:
entomopathogenBeauveriabassianastrainATCC74040)
•ReferenceproductsavailableinIPM:mostlysystemicinsecticides
•ReferenceactuallyusedinIPM:combinationofdifferentPPPs
Appropriate standards for comparison
Reference product vs. reference strategy: woolly apple aphid (Eriosiomalanigerum) on apple
11th OECD Expert Group on BioPesticides Seminar12

13. InfestationIndex = Σni*vi
ni=n. colonieswithineachInfestationclass vi;
vi = 1 (1-5 aphids), 2 (6-20 aphids), 3 (>20 aphids)
Appropriate standards for comparison
Reference product vs. reference strategy: woolly apple aphid (Eriosiomalanigerum) on apple
11th OECD Expert Group on BioPesticidesSeminar13

14. •Especiallyneededfordifficultand‘long-season’targetpestsanddiseases,whichareusually
controlledbyapplyingseveraldifferentPPPswithdifferentMoAsincombinationand/oralternation
•Possibleoptionsfortrialdesign:
•selectionofapplicationwindow(s),e.g.particularlydelicatephenologicalstage,suchasflowering
orharvestingperiod;periodsofhigh-lowriskofinfection;oneormoreoutofseveralpest
generations,etc.
•replacementofapplicationswithinsprayprogram
CompletelyandpartiallyUTCshouldbeincludedintrialdesign!
Efficacy evaluation within Integrated Programs
11th OECD Expert Group on BioPesticidesSeminar14

15. Selection of application window(s): brown spot of pear
•Causal agent: Stemphiliumvesicarium. Once conidia germinate, host-
specific toxins are produced, which cause symptoms.
•Common IPM practices: preventative sprays every 7-14 days from flower-
ingup to harvest, for a total of up to 20 (and sometimes more) sprays per
season. Curative fungicides are not effective!
•Organic farming: extremely limited number of authorized PPPs
•Economic importance: up to 10% losses of total production, in spite of
control measures applied. Levels of disease (5-10%) one year may be
followed by up to 90% infected fruit the following year.
•Possible application windows:
•during flowering
•during fruit development (period of highest risk of infection)
•close to harvest
Efficacy evaluation within Integrated Programs
11th OECD Expert Group on BioPesticidesSeminar15

16. Selection of application window(s): brown spot of pear
Bioprotectant: Bacillus amyloliquefaciensstrain D747
8 additionalfungicide sprays in alltreatedplots,
partiallyUTC included.
Efficacy evaluation within Integrated Programs
17 additionalfungicide sprays from 16 March to 7 Julyin
alltreatedplots, partiallyUTC included.
11th OECD Expert Group on BioPesticides Seminar16

17. 0
10
20
30
40
50
60
70
80
90
15 DA-A13 DA-B7 DA-C14 DA-C14 DA-D7 DA-E5 DA-F13 DA-F6 DA-G13 DA-G
% Leaf Severity
–
Powdery Mildew
UTC Standard Program SERENADE Program Skipped Applications
a
c
cd
b
1
st
Bs QST 713 App. 2
nd
QST 713 App.
A Trifloxystrobin
B Quinoxyfen
C Trifloxystrobin
D Quinoxyfen
E No application
F Trifloxystrobin
G No application
A Trifloxystrobin
B Quinoxyfen
C Trifloxystrobin
D Quinoxyfen
E Bs QST 713
F Trifloxystrobin
G Bs QST 713
A Trifloxystrobin
B Quinoxyfen
C Trifloxystrobin
D Quinoxyfen
E Triflumizole
F Trifloxystrobin
G Triflumizole
Disease control in grapes comparing an integrated program to a chemical program
Efficacy evaluation within Integrated Programs
Replacement of applications within spray program: powdery mildew on grapevine
Bioprotectant: Bacillus subtilis strain QST 713
11th OECD Expert Group on BioPesticidesSeminar17
QST 713 Program

18. Concluding remarks
•InmanyOECDcountriestherearepolicydiscussionsthatareleadingtothecallfortheadditionofmore
bioprotectantsforpestanddiseasemanagementtobeemployedinagriculture.
•Thereisaneedforappropriateregulationsforbioprotectantswithpredictablepathsandreasonable
timelineforreview.
•Thereisaneedforabetterunderstandingofthemodeofactionofbioprotectantsinordertoprepare
protocolsforefficacyevaluationwhichallowforobservationoftheeffectivenessbasedonappropriate
uses.Thisrequiresaflexibilityinmethodologytosuittheproductandcorrectlyconsideritsmodeof
action.
•Makingimprovementstotheregulatoryreviewandapprovalprocessforbioprotectants–includinginthe
considerationofefficacydata–willbeanimportantaspectofachievingthispolicygoal.
11th OECD Expert Group on BioPesticides Seminar18

19. Acknowledgements
•DrRomaLGwynn,IBMAGlobal
•DrUlfHeilig,IBMAGlobal
•DrGregWatson,BayerU.S.–CropScience
•DrSergioFranceschini,CBC(Europe)S.r.l.–BIOGARDDivision
•Growers
•Fieldadvisors,technicians,testingfacilities
11th OECD Expert Group on BioPesticides Seminar19