LOGO IITA
Purdue Improved Cowpea
Storage (PICS) – Potential for
Application in West Africa?
Kerstin Hell, Kukom Edoh Ognakossan and
Ousmane Coulibaly
Traditional storage system
• 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
• 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
Mortality rate (%) of insects in IRRI
Super bag (ISB) on maize
Days
after
S. zeamais
storage
P. truncatus
Mixture (S. zeamais + P. truncatus)
ISB
Control
ISB
Control
ISB
Control
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
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
-
-
Infestation with 10 insects
Infestation with 25 insects
92.48 ± 6.02 Aa
60
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
6 months of
3 months of
6 months of
storage
storage
storage
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
100 ± 0.00Aa
96.43 ± 2.33Aa
11.35 ± 1.71Bb
34.05 ± 2.69Ba
(Control)
Mean (± SE) within a column (row) followed by the same uppercase letter (lowercase) are not significantly different from each other at 5% probability level
Means numbers of
holes on PICS Bag and
PPB
Treatment
PICS (natural)
PsB
PPB
3 months
0.75 ± 0.75
6 months
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
Effect of PICS & IRRI Bag on maize postharvest pest after 3- and 6-month
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
0.47
1.95
1.52
0.00
0.00
0.00
0.00
± 0.24 Aa
± 0.23 Aa
± 0.47 Aa
± 0.34 Aa
± 0.00 Aa
± 0.00 Aa
± 0.00 Aa
± 0.00 Aa
0.75
0.30
2.47
1.35
0.00
0.00
0.00
0.00
± 0.38 Aa
± 0.11 Aa
± 0.69 Aa
± 0.41 Aa
± 0.00 Aa
± 0.00 Aa
± 0.00 Aa
± 0.00 Aa
0.62
0.96
234.37
238.75
147.05
355.05
44.77
191.65
±0.27 Aa
± 0.12 Ba
± 33.28 Ba
± 2.38 Ba
± 7.82 Ba
± 14.26 Bb
± 5.18 Ba
± 6.83 Bb
PICS
PPB (Control)
• 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
Effects of PICS & IRRI Bags on maize
grain losses after 3- and 6-months
Treatments
IRRI
PICS
PPB
Months after storage
3 months
6 months
0.37±0.05 Aa
0.32 ± 0.02 Aa
0.28±0.01 Aa
0.31 ± 0.01 Aa
9.56± 0.34 Ba
17.95± 0.51 Bb
• Losses were significantly lower in PICS & IRRIbags .
• No increase of losses in PICS & IRRI with storage.
• In polypropylene bags losses increased with
storage time reaching nearly 18%.
Maize prices
threeinlocal
Maize in
prices
threemarkets
local markets
Financial
benefits of PICS
Benefit Cost Ratio of the use of PICS bags
If bags would be reused
for a second storage
season the benefit/cost
ratio would increase to
3.7, 5.0 and 6.3
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)