Potential of PICS Bag for the Control of Larger Grain Borer (Prostephanus truncatus) - An Integrated Approach

Affognon H., A. Njoroge and L. Murdock

Presented at Purdue Improved Crop Storage Workshop: Lessons Learned in Developing and Implementing

Hermetic Storage

April 10-12, 2012 Accra, Ghana

MaizeMost important staple in SSA

Post-harvest losses of maize in SSA are substantial

Mainly due to insect pests among which the invasive Prostephanus truncatus (LGB)

Introduction

LGB was accidentally introduced into Africa some 30 years ago

The pest is present in 18 SSA countries

National losses of around 40% of the weight of stored grain,

In individual households this can reach as high as 100%

Control strategies - synthetic insecticides and fumigants

Chemical control - not widely adopted - socio-economic reasons

Eradication of the pest failed - beetle had already established itself in its natural forest habitat

A classical biological control campaign was launched in 1991 and Teretrius nigrescens was released as a bio-control agent

Introduction

Objective: To assess the potential of PICS bag for controlling LGB at farm level using an integrated approach

Components of the integrated approach

Disinfestation of maize grains with solar energy

Storing the maize in the PICS bags after the solar disinfestation

Methodology

Testing the integrated approach

Assessing the thermal death point of adults Prostephanus truncatus with oven in laboratory

Assessing the performance of PICS bag. A total of six (6) treatments were tested

T1: PICS bag + solar disinfested maize (25 kg)

T2: PICS bag + solar disinfested maize (25 kg) + 100 LGB (here the maize was infested and left for 4 days

before solar disinfestation)

T3: PICS bag + solar disinfested maize (25 kg) + 100 LGB

Methodology

C1: Ordinary woven polypropylene bag + solar disinfested maize (25 kg)

C2: Ordinary woven polypropylene bags + solar disinfested maize (25 kg) + 100 insects in each bag

C3: Ordinary woven polypropylene bag +Non solar disinfested maize (25 kg)

Parameters measured: Moisture content - Oxygen and Carbon dioxide in PICS bags – Weight loss – Number of live adults and larvae of LGB – Number of live adults of

Sitophilus – Germination – Aflatoxin contaminations

Methodology

Results

Grain borer mortality curves

Temperature (degrees celcius)

Cu

mm

ula

tive

pro

po

rtio

n m

ort

alit

y

50 55 60 65 70

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

30 minutes60 minutes90 minutes120 minutes

Grain borer mortality curves

Temperature (degrees celcius)

Cu

mm

ula

tive

pro

po

rtio

n m

ort

alit

y

50 55 60 65 70

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

30 minutes60 minutes90 minutes120 minutes

Thermal death point of adults Prostephanus truncatus Thermal death point of adults Prostephanus truncatus

Results

January moisture content (%)T1 12.39aT2 12.30aT3 12.39aC1 12.68aC2 13.31bC3 12.48a

March moisture content (%)T1 11.97aT2 12.22aT3 12.25aC1 11.98aC2 12.12aC3 12.16a

February moisture content (%)T1 12.03abT2 12.31bT3 12.46bC1 11.75aC2 12.07abC3 12.09ab

Performance of PICS bag

Results

Gas (O2 and CO2) evolution in PICS bagsGas (O2 and CO2) evolution in PICS bags

Performance of PICS bagPerformance of PICS bag

Results

Treatments LGB adults per 500g of

maize

LGB larvae per 500g of maize

Sitophilus adults per

500g of maizeMarch (60 days after)T1 0.00a 0.00a 0.00aT2 0.00a 0.00a 0.00aT3 1.00a 0.00a 0.00aC1 2.00a 0.00a 28.00cC2 11.33b 17.67b 20.00bC3 1.67a 0.00a 26.00c

Performance of PICS bag

Results

Weight lossWeight loss

Performance of PICS bagPerformance of PICS bag

Way forward

It is early to draw a conclusion, however, so far PICS bag seems to perform well

The monitoring will continue

Baseline data were collected on germination and aflatoxin contaminations

Germination tests and aflatoxin contaminations analysis will be performed after 3, 6 and 9 months

Economic analysis will be performed at the end of the experiment with price differential information that will

be collected in different zones in the country

Thank you for your attention