Effectiveness of Eucalyptus camaldulensis and Cymbopogon citratus essential oils in protecting rice stocks from Sitophilus oryzae and Sitotroga cerealella.

A. Togola, P.A. Seck, F.E. Nwilene, I.A. Glitho et D. Chougourou

OUTLINEIntroductionMaterial & methodsResultsConclusion

INTRODUCTION Rice production

• Rice is a staple food for millions of people in Africa

• Since 2008 its cropping area and production have increased in West Africa (FAOSTAT, 2011)

• Unlike the pass , rice is more and more stored for seeds, consumption and trade

Storage issues

• Rodents, insects, fungus, abiotic factors, etc.

• Quantitative losses due to insects reach 5% and 30% in 4 and 6 month of storage.

• Qualitative losses : physical, culinary and nutritional

• Economic losses: leading to the decrease in income of the actors of rice sector

INTRODUCTION

The objective of this study is:

To develop alternative technologies (to chemical methods) for an effective integrated protection of stored rice against insects pests.

INTRODUCTION

Sitophilus oryzae (Coleoptera:

Curculionidae)

Sitotroga cerealella (Lepidoptera: Gelechiidae)

MATERIAL & METHODS

Animal material:

Larve Adulte Larve Adulte

7

Plant material: Cymbopogon citratus

(Poaceae)

Essential oil

Eucalyptus camaldulensis(Myrtaceae)

8

• Impregnation of gunny bags (sacs en jute) Eucalyptus camaldulensis

3%, 4%, 5%, untreated check, Check with alcohol alone

Cymbopogon citratus 3%, 4%, 5% , untreated check,

Check with alcohol alone

Alcohol

• Infestation method in impregnated gunny bags

20 20

Paddy rice: 100g

Replication: 4

9

• Treatment of cotton bags (sacs en cretonne)Cymbopogon + cotton bag ( dose : 0.25ml/bag)Eucalyptus + cotton bag ( dose : 0.25ml/bag)Eucalyptus + Cymbopogon + cotton bag Cymbopogon + cotton bag + plastic filmEucalyptus + cotton bag + plastic film Eucalyptus + Cymbopogon + cotton bag + plastic filmCheck with cotton bag + plastic filmCheck with cotton bag alone Rep 4

20 20

Paddy rice: 100g

• Infestation method in cotton bags

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Data collected at 90 days after treatment:

• Population of emerged adults

• Percentage of weight loss (%)

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Treatments

Emerged population of

S. oryzae

Emerged population of

S. cerealella

Untreated check 51.0 ± 6.2a 345.7 ± 24,9aCheck with alcohol

alone 48.1 ± 3.4a 329.6 ± 21,5aC. citratus 3 % 51.5 ± 8.4a 113.2 ± 9,0b

C. citratus 4 % 37.2 ± 3.4a 98.5 ± 8,8bC. citratus 5 % 21.2 ± 2.6b 88.7 ± 4,0bE. camaldulensis 3 % 20.2 ± 2.0b 263.7 ± 20,4aE. camaldulensis 4 % 15.2 ± 2.6b 280.0 ± 19,4aE. camaldulensis 5 % 9.5 ± 3.1b 266.5 ± 32,4a

Table 1: Effect of essential oils on Sitophilus oryzae and Sitotroga cerealella population emerged in stored paddy rice inside gunny bags (Sac s en jute)

RESULTS

Figure 1: weight losses recorded 90 days after storage in ganny bags impregnated withCymbopogon citratus

Untreated check

Check with Alcohol

C. citratus 3%

C. citratus 4%

C. citratus 5%

0

2

4

6

8

10 a a

b

cd

Wei

ght l

osse

s of

pad

dy ri

ce (%

)

TraitementsPertes pondéralesEnregistrées (%)

Check with cotton bag alone 8,69b

Check with cotton bag + plastic film 4,78ab

Cymbopogon + cotton bag 3,53ab

Eucalyptus + cotton bag 3,88abEucalyptus + Cymbopogon + cotton bag 4,79abCymbopogon + cotton bag + plastic film 3,14abEucalyptus + cotton bag+ plastic film 3,76ab Eucalyptus + Cymbopogon + cotton bag + PF 1,83a

Table 2: Impact of cotton bags treatment on paddy rice weight losses (Sacs en cretonne).

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CONCLUSION

The use of the essential oils of C. citratus and E.

camalsulensis appeared to be a promising method

for protecting stored rice against S. cerealella and

S. oryzae. However, the method needs some

improvement in order to make the technology

cheaper for a large access by end users.

Thank you for your kind attention