Purdue Improved Cowpea Storage (PICS) – Potential for Application in West Africa?

Kerstin Hell, Kukom Edoh Ognakossan and Ousmane Coulibaly

LOGO IITA

• Environmental conditions, traditional farming methods, improper grain drying and storage practices facilitate quality reduction and insect infestation in African Post-harvest systems

• Grain losses due to Insects in West-Africa– >30% in maize stores infested with Prostephanus truncatus– 10-12 % in maize infested with Sitophilus zeamais

Traditional storage system

• Several African staple commodities are affected by high losses due to insects – maize, millet, groundnut, rice, sorghum and processed yam and cassava products

• Post-harvest Loss Network determined losses for cereals of 17.4% to 14.3% (2003 till 2008)

Hermetic storage trials at IITA-Benin• Testing of IRRI Superbags (‘09) and

PICS-Bags (‘09) for control of P. truncatus & S. zeamais on maize

• Testing of PICS Bags for control of insects in maize (’10 & ’12) and cassava chips (’11 & ‘12)

• Destructive sampling• Moisture content, insect species,

grain losses, holes on bags, CO2 and O2 levels

• Cost/benefit analysis to determine financial profitability PICS bag

Days after

storage

S. zeamais P. truncatus Mixture (S. zeamais + P. truncatus)

ISB Control ISB Control ISB Control

Infestation with 10 insects

60 96.30 ± 3.70 Aa 5.28 ± 0.19 Ab 83.45 ± 8.31 Aa 7.74 ± 1.14 Ab 92.05 ± 1.45 Aa 7.90 ± 1.98 Ab

90 98.04 ± 1.96 Aa 7.94 ± 2.98 Ab 92.70 ± 7.29 Aa 10.80 ± 2.38 ABb 87.80 ± 6.76 Aa 9.06 ± 2.04 Ab

120 100 Aa 10.38 ± 1.24 Ab 85.06 ± 5.24 Aa 24.29 ± 5.76 Bb 92.63 ± 7.36 Aa 19.82 ± 1.86 Bb

150 100 Aa 10.64 ± 3.05 Ab 100 Aa 25.51 ± 5.43 Bb 100 Aa 24.13 ± 2.15 Bb

Infestation with 25 insects

60 92.48 ± 6.02 Aa 7.59 ± 0.84 Ab 99.52 ± 0.47 Aa 7.77 ± 0.66 Ab 92.75 ± 4.46 Aa 9.70 ± 1.42 Ab

90 100 Aa 10.93 ± 0.13 Bb 87.97 ± 6.03 Aa 10.51 ± 1.47 Ab 50.08 ± 7.78 Ba 16.32 ± 1.26 Bb

120 100 Aa 14.01 ± 0.99 Cb 73.04 ± 16.33 Aa 19.41 ± 1.82 Bb 90.81 ± 9.18 Aa 22.27 ± 2.00 Bb

150 100 Aa 17.74 ± 1.16

Db

82.92 ± 14.38 Aa 21.83 ± 1.57 Bb - -

Mean (± SE) within a column (row) followed by the same uppercase letter (lowercase) are not significantly different from each other at 5% probability level

Mortality rate (%) of insects in IRRI Super bag (ISB) on maize

Mean (± SE) within a column (row) followed by the same uppercase letter (lowercase) are not significantly different from each other at 5% probability level

Mortality rate (%) of insects in IRRI Super bag and PICS on maize

Mortality rate (Mean % ± SE)a

Treatments P. truncatus S. zeamais

3 months of

storage

6 months of

storage

3 months of

storage

6 months of

storage

IRRI 100 ± 0.00Aa 100 ± 0.00Aa 90.97 ± 4.40 Ab 100 ± 0.00Aa

PICS 100 ± 0.00Aa 100 ± 0.00Aa 95.83 ± 4.16Aa 100 ± 0.00Aa

PPB

(Control)

100 ± 0.00Aa 96.43 ± 2.33Aa 11.35 ± 1.71Bb 34.05 ± 2.69Ba

Means numbers of holes on PICS Bag and

PPB Treatment 3 months 6 months PICS (natural) 0.75 ± 0.75

0.50 ± 0.50

PICS (artificial)

0.00 ± 0.00 1.25 ± 0.75

PPB (natural) 308.50 ± 36.39

322.25 ± 19.74

PPB (artificial)

344.25 ± 40.53 350.75 ± 25.38

PsB PPB

Effect of PICS & IRRI Bag on maize post-harvest pest after 3- and 6-month

• Pest densities were significantly reduced in hermetic bags compared to control polypropylene Bags (PPB) (P=0.018)

• In control bag insect densities increased significantly with storage time (P < 0.0001)

• In hermetic storage, P. truncatus was found ONLY when maize was artificially infested whereas in the control it all bags had this species

Number of adult insects per kg of maize grains (Mean ± SE)a

P. truncatus S. zeamais C. quadricolis Tribolium spp.

Treatments 3 months of storage 6 months of storage 3 months of storage 6 months of storage 3 months of storage 6 months of storage 3 months of storage 6 months of storage

IRRI 0.62

± 0.24 Aa

0.47

± 0.23 Aa

1.95

± 0.47 Aa

1.52

± 0.34 Aa

0.00

± 0.00 Aa

0.00

± 0.00 Aa

0.00

± 0.00 Aa

0.00

± 0.00 Aa

PICS 0.75

± 0.38 Aa

0.30

± 0.11 Aa

2.47

± 0.69 Aa

1.35

± 0.41 Aa

0.00

± 0.00 Aa

0.00

± 0.00 Aa

0.00

± 0.00 Aa

0.00

± 0.00 Aa

PPB (Control) 0.62

±0.27 Aa

0.96

± 0.12 Ba

234.37

± 33.28 Ba

238.75

± 2.38 Ba

147.05

± 7.82 Ba

355.05

± 14.26 Bb

44.77

± 5.18 Ba

191.65

± 6.83 Bb

Effects of PICS & IRRI Bags on maize grain losses after 3- and 6-months

• Losses were significantly lower in PICS & IRRI-bags .

• No increase of losses in PICS & IRRI with storage. • In polypropylene bags losses increased with

storage time reaching nearly 18%.

Treatments Months after storage 3 months 6 months

IRRI 0.37±0.05 Aa 0.32 ± 0.02 Aa PICS PPB

0.28±0.01 Aa 9.56± 0.34 Ba

0.31 ± 0.01 Aa 17.95± 0.51 Bb

Financial benefits of PICS

If bags would be reused for a second storage season the benefit/cost ratio would increase to 3.7, 5.0 and 6.3

Maize prices in three local marketsMaize prices in three local markets

Benefit Cost Ratio of the use of PICS bags

Efficacy of PICS on cassava chips

• Number of P. truncatus was not significantly different between treatments

• Losses were beyond economical levels, exceeding 8% after 6 months of storage

• Oxygen levels in both treatments reached 18.69% and 19.12% after 8 months of storage.

What have we learned?• Hermetic storage technology effective for maize, • In regions with high levels of P. truncatus (more

than 1 Pt per kg) precaution about technology• High moisture content of grains in PICS bags can

reduce germinability and lead to quality loss • Bags are penetrated from

inside to outside• Technology not effective

for traditional cassava and yam chips

What R&D is missing• Need for low-cost energy efficient dryers to improve

grain drying to avoid mycotoxins & moisture meters• Potentially increase effectiveness of PICS bags by

including another technology to reduce insect attack (oils, natural substances, ???)

• Test PICS bags for other commodities and include further quality parameters (nutrition, processing characteristics, toxins)

• All stakeholders need to address the persistent high post-harvest losses (advocacy)