Evaluating PICS for Groundnut

H. Sudini 1, C.L.L. Gowda 1, V. Margam 2 and L.L. Murdock 3

1 International Crops Research Institute for the Semi-Arid Tropics, Patancheru, India

2 Computational Biosciences Research Center, KAUST, Saudi Arabia3 Dept. of Entomology, Purdue University, West Lafayette, IN, USA

Purdue Improved Crop Storage Workshop, April 10-12, 2012, Accra, Ghana

Groundnut (Arachis hypogaea)

Groundnut (Peanut) is an important food legume in semi-arid tropical countries

Grown in more than 100 countriesIndia alone ~5.6 M tons (FAOSTAT

2010)Important post-harvest constraints

Aflatoxin contaminationBruchid infestation

• Mycotoxins, the secondary metabolites of Aspergillus, Fusarium, and Penicillium, are among the most common natural contaminants of foods and feeds

Mycotoxins

Factors affecting aflatoxin contamination during post-harvest

Abiotic•Water activity•Temperature•Gas composition

Biotic•Storage insect pests

Groundnut Bruchid

Caryedon serratus (olivier) is the most important storage pest

The adult is reddish brown beetleFemale beetle attaches its eggs to the pod wallThe eggs are small and milky-white in color and

hatch about 8 daysGrubs are stout and fleshy and they complete

four instars in about 23 daysFull grown grub makes a round hole on the pod

wall through which it leaves the pod and pupate at the bottom. Pupal period ranges between 14 and 16 days

Grubs bore through the pod wall, feed on the internal contents of the seed and make them hollow

EggPupa

Linkage

Venu Margam from Purdue visited ICRISAT during late 2010

Capacity building Introduced to Dr. MurdockDeveloped a proposal to test the

efficacy of PICS bags for Groundnut storage

Subsequently Purdue provided financial assistance

PICS experiment on Groundnut @ ICRISAT

Important underlying goalsTo check bruchid damage levelsTo monitor aflatoxin contamination levelsTo test seed viability (Germination)

Two independent experiments with different moisture levelsIst Batch experiment- 4 months storageApproximately 8% MC

Methodology

•A generalized experiment with 3 replications

•25kg unshelled pods•5% Groundnut Bruchid infestation (approximately 1.25 kg of infested pods)

•On an average 6-8 adults per every 100 grams of pod

Methodology

Observations recorded onGas composition at

regular intervals (O2/CO2 Analyzer-Mocon)

Germination percentage (seed viability before and after the experiment)

Aflatoxin levels before and after the experiment (indirect competitive ELISA)

Sample Processing Representative sample 100 g of subsample

made into powder 20g of powder added to

100ml of 70% methanol Shake it for 30 min. After filtration, the

methanol extracts were stored at 4oC till they used

ELISA Plate Design

• Read the plate at 405 nm• Higher toxin concentration confer light color that leads to

low OD value and vice versa

Results-Gas composition

O2 Level CO2 Level

Infested PICS 1 9.22 7.04PICS 2 12.17 5.65PICS 3 6.79 8.27Gunny Bag 1 20.18 0.15Gunny Bag 2 20.31 0.13Gunny Bag 3 20.30 0.17

Uninfested PICS 4 6.15 8.84PICS 5 5.41 8.32PICS 6 10.80 4.94Gunny Bag 4 20.07 0.15Gunny Bag 5 20.13 0.13Gunny Bag 6 20.19 0.12

Results-Insect damage levels after opening the bagsRep 1 Rep 2 Rep 3

InfestedDamaged pod

Un damaged pod

Damaged pod

Un damaged Pod

Damaged pod

Un damaged Pod

PICS Bag 1 16 84 12 88 19 81PICS Bag 2 56 44 62 38 55 45PICS Bag 3 20 80 24 76 22 78

Gunny Bag 1 73 27 72 28 74 26Gunny Bag 2 86 14 92 8 89 11Gunny Bag 3 87 13 83 17 82 18

Uninfested/ControlPICS Bag 4 3 97 5 95 3 97PICS Bag 5 7 93 6 94 4 96PICS Bag 6 4 96 2 98 3 97

Gunny Bag 4 79 21 82 18 72 28Gunny Bag 5 38 62 43 57 48 52Gunny Bag 6 24 76 25 75 33 67

Results-Germination levels

Before starting the experiment

After the experiment

InfestedPICS 1 94% 92 %PICS 2 95% 91%PICS 3 98% 95%Gunny Bag 1 90% 94%Gunny Bag 2 97% 95%Gunny Bag 3 97% 94%Uninfested/ControlPICS 4 94% 93%PICS 5 97% 96%PICS 6 93% 92%Gunny Bag 4 95% 97%Gunny Bag 5 92% 92%Gunny Bag 6 98% 91%

Results-aflatoxin levels

Before the experiment

Aflatoxin content in ppb after the experiment

Sample 1 Sample 2

Sample 1 Sample 2

InfestedPICS 1 1.4

18.11.7 0.0

PICS 2 823.8 1526.4

0.0 4.0

PICS 3 1.7 0.0

0.0 2.5

Gunny Bag 1 33.6 11.8

0.0 1.5

Gunny Bag 2 0.0 0.0

0.0 2.3

Gunny Bag 3 5.6 0.0

0.0 5.3

Uninfested/ControlPICS 4 25.3

46.80.0 1.6

PICS 5 0.0 0.0

0.0 0.0

PICS 6 15.5 23.4

0.0 0.0

Gunny Bag 4 0.0 18.3

0.0 0.0

Gunny Bag 5 80.0 52.9

0.0 0.0

Gunny Bag 6 168.7 78.5

0.0 0.0

Visibility of bruchid damage

Conclusions

Large air spaces in the PICS bags with unshelled pods could affecting the gas composition

Since aflatoxin contamination is also a pre-harvest issue, any toxin produced remains in the produce

Sampling variation is a huge factor in assessing aflatoxin levels

Activity2 – Farmer Trials

As part of an IFAD project a group of groundnut farmers and extension agents visited ICRISAT on April 4th, 2012.

Conducted a demonstration of PICS bag usage.

Activity2 – Farmer Trials

Showed them the trials setup in the laboratory and difference in the control vs PICS stored groundnut.

Convinced, the farmers requested bags for testing. Feedback will be obtained from them after 4 months.

Lessons learned/Way Forward

Micro scale level studies are to be conducted to understand the exact relationship between hermetic storage principle (gas composition) and Aspergillus flavus growth and subsequent aflatoxin contamination

The Groundnut material representing different components of resistance to aflatoxin contamination need to be studied separately (circumstantial evidence for varietal differences)

Thank you