biocontrol of aflatoxins exists as a practical tool ... · 2 percent of a. flavus 0 10 20 30 40 50...
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di Aspergillus flavus e festione della filiera, un future per maiscoltura e “latte italiano di qualità” 9 febbraio, 2017, Universita Cattolicà del Sacro Cuore, Piacenza
di Aspergillus flavus e festione della filiera, un future per maiscoltura e “latte italiano di qualità” 9 febbraio, 2017, Universita Cattolicà del Sacro Cuore, Piacenza
Peter J. Cotty,Agricultural Research Service, U.S. Department of AgricultureSchool of Plant Sciences, University of Arizona, Tucson
Peter J. Cotty,Agricultural Research Service, U.S. Department of AgricultureSchool of Plant Sciences, University of Arizona, Tucson
1970s, Arizona
1980s, ArizonaFirst Tests
1988
Vegetative Compatibility Analyses
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CAP = Cluster Amplification Pattern
Simple Sequence Repeat Analyses
First Patent Application: 1989 First Conference with Environmental Protection Agency: 1992 Used on commercial crops in US since 1996. Three Products Currently Registered Over 1 Million Acres Treated Annually Registered Target Crops: Maize Grain, Maize Silage,
Pistachios, Cottonseed, Peanut (Almond & Fig in registration process).
Aflatoxin Biocontrol in the US
Biocontrol in Africa There is Severe Human Exposure to Aflatoxins in Several
African Nations. Products registered for use in Nigeria, Kenya,
Senegal/Gambia. Target Crops: Maize & Groundnut.
The Wall Street JournalTuesday March 16, 1993
The Wall Street JournalTuesday March 16, 1993
Biocontrol of aflatoxins exists as a practical tool because of farmers.
Genotypes of Aspergillus flavus, an important cause of aflatoxin contamination, vary widely in ability to
produce aflatoxins.
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Per
cent
of
A. f
lavu
s
0
10
20
30
40
50
60
1 2 3 4 5 6
Field 1 Field 2
Aflatoxin Produced in Culture (log ppb)
Aflatoxin-ProducingPotential
Aflatoxin-ProducingPotential
Field 1 = Low,3,400 ppb
Field 1 = Low,3,400 ppb
Field 2 = High,54,000 ppb
Field 2 = High,54,000 ppb
Aflatoxin Production by A. flavus from Two Fields
Fungi Vary Across Areas in Aflatoxin-Producing Ability
Farmers apply atoxigenic strains to reduce the average aflatoxin-producing potential of fungi on farms & this reduces vulnerability of crops to aflatoxin contamination
Fungi Vary Across Areas in Aflatoxin-Producing Ability
Farmers apply atoxigenic strains to reduce the average aflatoxin-producing potential of fungi on farms & this reduces vulnerability of crops to aflatoxin contamination
Mycological Research 101:698-704; 1997.
As Applied After Fungal Growth
The atoxigenic fungi are applied on non-viable grain (sorghum, wheat, and barley are used).
Biocontrol Products: AF36, Prevail™, Aflaguard™, AflaSafe™, AF-X1™, FourSure™
As AppliedAs Applied
J F M A M J J A S O N DMonth
0
100
200
300
400
500
=total crop biomass=total crop biomass=total A. flavus=total A. flavus=soil A. flavus=soil A. flavus
Aspergillus Populations Rapidly Increase with Crop BiomassFounder Effects Drive Shifts in Population Structure.
Aspergillus Populations Rapidly Increase with Crop BiomassFounder Effects Drive Shifts in Population Structure.
Properly timed applications of atoxigenics can direct population shifts
to improve the safety of Aspergillus populations associated with crops
Afl
ato
xin
B1
(ng
/g X
10,
000)
Isolates (%) in Applied Atoxigenic Strain
0
1
2
3
4
5
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9
0 20 40 60 80 100
Dots Represent Values for Replicate Plots
Aflatoxin in Crop versus Atoxigenic Incidence
Cotty, 1994. Phytopathology:1270-1277.
Aflatoxin (ppb)
Area Samples (#) AF36 (%) Mean Range
GraysonNorth
17 96 a 12 a 0 to 48
GraysonSouth
16 98 a 15 a 0 to 38
GraysonControl
8 24 b 230 b 5 to 530
Commercial Maize: North Central Texas 2008
Means in the same column with different letters are significantly different by Tukey’s HSD test, P < 0.001.
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Fungi move between fields and across areas.
Take a bigger view: Not just one field, one farmer, one crop.
We can protect whole agricultural systems from aflatoxins including all affected industries and improve the environment.
57% AF36
92% AF3660% AF36
42% AF36
1% AF364% AF36
3% AF36
0% AF36
Blue dots represent the percent of the A. flavus
community composed of AF36
Soil Community Before Treatment Community on Crop After Ginning
Application Rate = 10 lb/acre
0.5 miles
Treated Field Treated Field
Application of Atoxigenic Strain AF36 in Commercial Cotton Influences the Composition of Fungi on Crops in both Treated and Nearby Fields
Data from 564 vegetative compatibility analyses.
Field Fields
AF36
(% A. flavus)
S strain
(% A. flavus)
A. flavus
(CFU/gram)
type (#) 1996 1997 1996 1997 1996 1997
Treated 3 4% ab 85% a 52% a 4% d 582 a 365 a
Adjacent 4 2% b 48% b 41% a 18% c 411 a 157 a
Diagonal 4 2% b 16% c 52% a 33% b 61 a 100 a
Other 4 9% a 9% c 43% a 50% a 109 a 98 a
Composition of Aspergillus flavus Communities in Soil of Treated and Nearby Fields in May 1996 Prior to Application of AF36 and
in May 1997 One Year After Application
TreatedAdjacentOther
Diagonal DiagonalOther Other Other
OtherOtherAdjacent
Adjacent
82%
53%
96%100%
0% 0% 0% 1% 17% 11%
77%74%
0%
20%
40%
60%
80%
100%
Pa
rha
mS
oil
Ru
the
rfo
rdS
oil
Pa
rha
mC
orn
Ru
the
rfo
rdC
orn
Pa
rha
mC
orn
Ru
the
rfo
rdC
orn
2008 2008 2008 2008 2009 2009
Per
cen
t o
f A
sper
gil
lus
flav
us
Grayson County, Texas: Carry Over to the Second Year Crop
= Atoxigenic isolate AF36
= S Strain, produces very high aflatoxins
Crop Treatment Year
Crop Year After Treatment
Soil Before Treatment
Percent AF36™
Percent Aflaguard™
Percent other A. flavus
Not Treated in 2015 Atoxigenic Biocontrol Agents on Harvested Corn
From Commercial Field Northcentral Texas
Area-Wide & Multi-Year Effects in Commercial AgriculturePie charts indicate percent A. flavus composed of the two EPA registered
active ingredients on maize harvested from the indicated spots. Values in each pie result from Vegetative Compatibility Analyses on 16 isolates (160 total).
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Equator
15° N
30° N
Equator
30° S
15° S
Wuhan(37 m)
Nanning(80 m)
Nampula(431 m)
Machakos(1,138 m)
Kaolack(26 m)
Phoenix(331 m)
Peanut
Corn
Dallas(131 m)
Pistachio
Corn
ACRPC, Phoenix
IITA, Ibadan
KALRO Katumani, Machakos
Italy
Cotton
During Crop DevelopmentIrrigation, Weed Control, Fertilize
Best cultivars, Insect Control
During transportRapid, Dry, No Damage
During ProcessingSort, Cull, Discard, Add binders.
During StorageDry, prevent moisture, cool
Prevent damage: insects, rodents
Prevent Formation of Dangerous Aflatoxin Levels
Protect Crops From Field…
…to Mouth
Since 2009 thousands of farmer’s fields have been treated in Nigeria, Kenya, Senegal, Burkina Faso, Zambia, Tanzania, and Ghana.
Reductions in aflatoxin contamination consistently average over 80% both at harvest and after storage.
Single applications are made at 10 kg/hectare
Nigeria
Senegal
As in the US, in Africa the biocontrol fungi survive between seasons allowing
for long-term and cumulative benefit.
“Emerging Risks in the Global Food System”
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74 ppb - Treated1,133 ppb - Control
93.5% Reduction
Mutomo, Kitui County, Kenya: 2012 TestsShort Rain Season Farmer Field Trials
DeadlyAverage 2,750 ppb!
Range 1,790 ppb to 3,710 ppb.
Safe Food
510 ppb
Aflatoxin Content(ppb)
Selection of atoxigenics for Kenya: Probst, et al. 2011. Plant Disease 95:212-218.
0
100
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400
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700
Not Treated Treated
20 ppb
µg/
kg (
ppb)
Tot
al A
flato
xins
Nigeria: Treated and control crops were harvested and stored under poor conditions for four months.
Atoxigenics stay with the crop from treatment, ………through harvest, storage, and consumption.
Atehnkeng, et al. 2014. Biological Control 72:62-70.
Area-wide Programs provide efficacy across cropping systems and additional health benefits. Area-wide Programs are less expensive (per hectare), provide for long-term commitment to aflatoxin elimination, protect all crops and remediate the area’s reputation.
Biocontrol fungi move from treated fields across areas
Multiple Crops Benefit From the Same Biocontrol Fungus
Biocontrol is Area-wide Management Area-wide Aspects can be Optimized
Atoxigenics persist in soils, on crop debris, on non-crop plants
Manufacture is easy. Biocontrol products like AF-X1 are made by a Farmer Organization in Arizona, and in a factory in Nigeria. Factories to make biocontrol products are under construction in Kenya and Senegal. manufacturing under construction at Katumani Station of KALRO in Machakos, Kenya. The facility will make Aflasafe KE01
December 2014
April, 2016
Producing the Biocontrol Product:
Manufacturing
Agricultural Research Service, USDASchool of Plant Sciences, University of Arizona
Work in Africa led by: Dr. Ranajit Bandyopadhyay Int. Institute Tropical AgricultureIbadan, Nigeria
Work on Tree Crops led by: Dr. Themis Michailides
University of California, DavisParlier, California
Work in Italy led by: Dr. Paola Battilani Universitá Cattolica del Sacro CuorePiacenza, Italy
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Agricultural Research Service, USDASchool of Plant Sciences, University of Arizona
There are many atoxigenic strainsSelect strains best adapted to rotations, ecosystems, & climates
Crops are infected by complex communities of diverse fungiWe can influence aflatoxin-producing ability of fungal communities resident in production areas
through crop rotations, agronomic practice, and by applying atoxigenic strains
Atoxigenics are Already Present on the CropJust increasing the frequency of endemic strains & natural interference with contamination
Treatments have Long-Term Influences & Cumulative Benefits
All Crops in an Area May Benefit From Applications
Atoxigenic Strains can be Applied Without Increasing Infectionand without increasing the overall quantity of A. flavus on the crop & throughout the environment