Sitotroga cerealella Olivier, 1789 - Angoumois Grain Moth

Summary

The grain moth is found throughout the warmer parts of the world. It is a pest of stored maize and a very broad range of other stored products. The grain moth has a very broad host range. The larvae (caterpillars) feed internally on maize grains

Common Names

English: Angoumois grain moth, grain moth, rice grain moth, rice moth

Local name: Tanzania, kipepeo wa mahindi

Synonyms

Alucita cerealella Olivier, 1789;Epithectis palearis Meyrick, 1913;Gelechia arctella Walker , 1864;Gelechia melanarthra Lower, 1900;Syngenomictis aenictopa Meyrick, 1927;Tinea hordei Kirby & Spence, 1815

Taxonomic Position

Phylum: Arthropoda; Class: Hexapoda (Insecta); Order: Lepidoptera; Family: Gelechiidae

Origin and Distribution

The grain moth is found throughout the warmer parts of the world and has even been found in the UK but has not established there.

Description

The adult grain moth is small (5-7 mm long with its wings folded) with a wingspan of 10-20 mm. The head, thorax and thin and thread-like (filiform) antennae are pale brown. The forewings are elongate, pale brown/golden yellow with a few blackish tinges. The hind wings are light greyish-brown with long lashes along the edges. The abdomen is brown. Its eggs which are oval but flattened at one end are white when laid but they quickly change to a reddish colour. The larva completes its development within a single grain so is rarely seen. Its body is yellowish-white and its small head , which is retracted into its body, is yellowish-brown. The pupa is reddish-brown.

Life Cycle

The adult lives for up to 15 days during which the female may lay up to 200 eggs although 40 is a more average number. The eggs are laid singly or in clumps of variable numbers. The newly emerged larvae bore into the grain where they will complete their development. The rate of development is dependent on temperature, humidity and the host. At 25°C and a relative humidity of 70% larvae take about 30 days to develop in maize. The pupal stage lasts about 10 days but can be as quick as 5 days. The newly emerged adult pushes through the window of the seed coat, leaving a small, but characteristic, round hole, usually in the crown end of the grain. Adults are strong fliers and can disperse easily. However, they are not strong and are can only infest the outermost layers of stored grain if it is closely packed.

Pest Destructive Stage

Larva or caterpillar

Host Range

Major crops affected by the grain moth include maize, oats, barley, rice, pearl millet, rye, sorghum and wheat.

Host Lifestage Affected

Post-harvest and storage although some plants can be attacked at the fruiting stage

Host Plant Part Affected

Seeds and grains

Damage Symptoms

Damage is initially difficult to detect as the larvae complete their development within a single grain. The larva or caterpillar produces a visible ‘window’ just below the surface of the grain when it constructs the chamber in which it pupates. Flour dust from internal feeding can spill from the grain once the grain moth has emerged.

Pest Management

Detection methods
Because the grain moth develops within a single grain it is difficult to detect damage until the characteristic ‘window’ is produced. Visual inspection can be used and the adults can be trapped using food-bait traps and pheromone traps.
 
Cultural practices
Late planting and early harvest is a potentially useful method for reducing pre-harvest losses caused by the grain moth. Methods of reducing humidity in grain stores such as plastering the walls with mud can reduce or help minimise infestation levels. Periodic inspection and removal of infestations can be effective especially if the grain is closely packed so that infestations are limited to the outermost layers. The use of resistant varieties can be effective for some crops.
 
Biological pest control
The grain moth is affected by a variety of parasites, parasitoids and predators that affect it at all stages. The editors could not find information on the effectiveness of these species as grain moth control agents.
 
Controlled atmosphere
Where suitable infrastructure exists, low oxygen and carbon dioxide-enriched atmospheres can be used to control stored product pests.

Freezing and Heating
Where the infrastructure exists, freezing for several days and heating for 24 hours have proved to be effective control methods for stored product pests.

Chemical Control
Standard fumigation and insecticide treatments can be effective against grain moth. For example, for maize stored on the husk a combination of fumigation with phosphine and treatment with methacrifos has been found to be effective. However, grain moths appear to have developed resistance to some insecticides in some parts of the world. Pesticides are poisons so it is essential to follow all safety precautions on labels.
 
Natural Products
Natural products including biogas derived from cattle manure and dried leaves of wild sage (Lippia geminata) have been found to be effective repellents against the grain moth.

Sources of Information and Links

CABI. (2007). Sitotroga cerealella (Angoumois grain moth) datasheet. Crop Protection Compendium, 2010 Edition. CAB International Publishing. Wallingford, UK.

Dent D. (2000). Insect pest management.CAB International Wallingford, UK

Infonet-biovision. http://www.infonet-biovision.org/default/ct/91/pests. Accessed on 28 Jan 2010.  

Gaby S. (1988). Natural crop protection in the tropics. Margraf Publishers Scientific books, Germany. 

Krischik V.A., Cuperus G. and Galliart D. (1995). Stored Products Management, 2nd Ed. Oklahoma State Univ. 204 pp.

http://www.grainscanada.gc.ca/storage-entrepose/pip-irp/lgb-ppg-eng.htm#d accessed on 15/5/2010.

Youdeowei A. (1993). Pest and vector management in the tropics, Longman group Ltd., England .

 

Editors

Anne M. Akol, Makerere University; Maneno Y. Chidege, Tropical Pesticides Research Institute; Herbert A.L. Talwana, Makerere University; John R. Mauremootoo, BioNET-INTERNATIONAL Secretariat.

Acknowledgments

We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke