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AB 2111 POSTHARVEST BIOLOGY

RICE WEEVILSitophilus oryzae

ByW.A.G.E.WIJELATH (AG/12/FT/024)

N.H.G.T.MADUSHANI (AG/12/FT/012)Department of Food Science and Technology

Faculty of AgricultureUniversity of Peradeniya

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Content

• Taxonomy• Life cycle• Morphology• Behaviour• Habitat• Signs of infestation• Damages• Control

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Taxonomy

Kingdom : AnimaliaPhylum : ArthropodaClass : InsectaOrder : ColeopteraFamily : CurculionidaeSubfamily : DryophthorinaeGenus : Sitophilus Species : S. oryzae

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Life Cycle

Consists of four stages

• Egg stage

• Larval stage

• Pupa stage

• Adult stage

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eggs

larva

pupa

adult

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Morphology

Larvae

•White to creamy white• Legless• Humpbacked• Fleshy grub• Soft

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Pupa

• White• Black, hard head• Movable segments

Adult

• 2-3 mm in length• Reddish brown to black in colour• 4 light yellow or reddish spots on elytra• Long, slender snout

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• Irregularly shaped pits on thorax

• Smooth, narrow strip extending down the middle of the back

• Fully developed wings

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Behaviour

• Internal feeders

• Active fliers

• Attracted to lights

• When disturbed, adults pull in their legs, fall to the ground, and

feign death

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Habitat

Usually found in

• Grain storage facilities

• Food processing plants

• Food markets

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They usually infest

• Stored rice

• Wheat

• Corn

• Rye

• Barley

• Sorghum

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Signs of Infestation

• Heating at the surface

• Increased moisture levels

• Seeds with round holes

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Damages

• Larvae develop within the seeds consuming the

endosperm• Adults feed on whole seeds or flour• The adult leaves a large, ragged exit hole in the kernel • Feeding contributes to heating and infested grain is often

damp due to moisture added by the insects’ respiration

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Control

• Preventing the insects from entering the storage

• Pest-proof containers

• Proper bin sanitation before introduction of new grain

• Cleaning bins regularly

• Addition of dry ice

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• Fumigation

• Application of insecticide

• Use of natural repellents

• Locating and removing all potentially infected food sources

• Repackaging products in new uninfected packages

• Freezing infected food below -17.7°C (0°F) for three days

• Heating to 60°C (140°F) for 15 minutes

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Reference• Public Health Vectors and Pests (2013) Rice Weevil [online] Available from:

http://www.kznhealth.gov.za/environ/vector/riceweevil.htm [Accessed on: 05/05/2015]

• The Pennsylvania State University (2015) Weevils on Stored Grain [online] Available from: http://ento.psu.edu/extension/factsheets/weevils-on-stored-grain [Accessed on: 05/05/2015]

• Canadian Grain Commission (2013) Rice weevil [online] Available from: https://www.grainscanada.gc.ca/storage-entrepose/pip-irp/rw-cr-eng.htm [Accessed on: 05/05/2015]

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Thank You