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Adult of Plodia interpunctella. Photo; "Pudding4brains" (Public Domain) - http://en.wikipedia.org/wiki/File:Plodia_interpunctella_top_43.jpg#file
Larva of Plodia interpunctella. "Pudding4brains" (Public Domain) - http://commons.wikimedia.org/wiki/File:Plodia_interpunctella_lrv_80.jpg
Larva of Plodia interpunctella. Photo: USDA, ARS (Public Domain)
Pupa of Plodia interpunctella. Photo: USDA, ARS (Public Domain)
Plodia interpunctella adult. Photo: USDA, ARS (Public Domain)
The Indian meal moth is found in a wide range of climate throughout the world. It can infest all types of dried food such as grain products, seeds, dried fruit, dog food and spices. The larvae (caterpillars) feed externally on maize grains but most of the damage to stored products is through contamination with the massive amounts of silk spun by the moth that accumulate faecal pellets, cast skins and egg shells.
Indian meal moth, mealworm moth
Ephestia glycinivora Matsumura, 1917; Ephestia interpunctella Hübner; Plodia castaneella (Reutti, 1898); Plodia glycinivora (Matsumura, 1917); Plodia interpunctalis (Hübner, 1825); Plodia latercula (Hampson, 1901); Plodia zeae (Fitch, 1856); Tinea castaneella Reutti, 1898; Tinea interpunctalis Hübner, 1825; Tinea interpunctella Hübner, ; Tinea zeae Fitch, 1856; Unadilla latercula Hampson, 1901
Phylum: Arthropoda; Class: Hexapoda (Insecta); Order: Lepidoptera; Family: Pyralidae
The Indian meal moth originated in
The eggs are about 0.5 mm in diameter and are laid singly or in clusters. The egg surface is sculptured unlike the eggs of Coleopteran stored product pests. The young larvae are white with a brown head with older larvae usually yellowish-white with green or pink tinges depending on diet. The larvae have five pairs of prolegs. The larvae grow to about 12 mm in length at maturity. The larvae pupate in a silk cocoon or unprotected. Adults are 5–10 mm in length with a wingspan of 16–20 mm. The outer half of their forewings is bronze, copper, or dark grey in colour, while the upper half are yellowish-grey, with a dark band at the junction between the two.
The entire life cycle of this species may take between 30-300 days. Optimum conditions are 30-35° C and 25% relative humidity. Female moths lay between 60 and 400 sticky eggs on food surfaces. The eggs hatch in 2 to 14 days. The larvae , which are external feeders (i.e. they do not burrow into the grain) begin to feed within a few hours of hatching and trail a silken thread which binds food, faecal pellets and cast skins together. The larval stage lasts from 2 to 41 weeks during which there are 5-7 instars. They pupate in a thin cocoon from which they emerge after 7 days under optimal conditions. Adults do not feed and are generally short-lived (around 7 days). The adult moths fly at dusk and during the night.
This species can infest all types of dried food such as grain products, seeds, dried fruit, dog food and spices.
seeds and grain
Most of the damage to stored products occurs when the larvae spin massive amounts of silk that accumulate faecal pellets, cast skins, and egg shells in food products. The damage to stored products due to this contamination exceeds the amount of food eaten by the insects. In large grain stores feeding is concentrated at the surface as the larvae do not burrow much.
Indian meal moth larvae are much more likely to be seen than adults. The mix of webbing and excreta is characteristic and pupae can be detected in their silk cocoons on the side of bags and other surfaces.
Elimination and exclusion are key elements in controlling pest populations of this moth. If a population is discovered, all infested material should be either discarded or treated. Any susceptible food source should be placed in sealed containers. In most cases, infested materials, especially small amounts, should be discarded and removed quickly from the premises. The severity of an Indian meal moth infestation can be reduced by good store hygiene which includes cleaning the store between harvests, immersing grain sacks in boiling water and fumigating the store to eliminate residual infestations and the selection of only uninfested material for storage.
The removal of larvae from the grain by sieving can reduce populations but this is very labour-intensive. The addition of inert dusts such as ash and clay to the grain can reduce insect numbers by causing the insects to die from desiccation.
The egg parasitoid Trichogramma evanescens can be mass released to control Indian meal moth although the authors were not able to find any information on the effectiveness of this method in storage facilities.
Controlled atmosphereWhere suitable infrastructure exists, low oxygen and carbon dioxide-enriched atmospheres can be used to control stored product pests.
Freezing and HeatingWhere the infrastructure exists, freezing for several days and heating for 24 hours have proved to be effective control methods for stored product pests.
Chemical controlNumerous insecticides have been used to control Indian meal moth populations, these includes; chlorpyrifos-methyl and chlorpyrifos-methyl plus methoprene (insect growth regulator). Fumigation of grain stocks with phosphine will eliminate existing infestations but will not protect against re-infestation. Insecticide fogging at dusk and dawn (peak flying times) can control adult Indian meal moths. Pesticides are poisons so it is essential to follow all safety precautions on labels.
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PaDIL – Plant Biosecurity Toolbox. Indian meal moth Plodia interpunctella. http://www.padil.gov.au/pbt. Accessed on 12 Jun 2011.
van Rykeghem A. (2004). Stored Product Pests. In Handbook of Pest Control. Hedges SA (editor). 9th Edition. GIE Media. Cleveland. 1397 pp.
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Anne M. Akol, Makerere University; Maneno Y. Chidege, Tropical Pesticides Research Institute; Herbert A.L. Talwana, Makerere University; John R. Mauremootoo, BioNET-INTERNATIONAL Secretariat.
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).
BioNET-EAFRINET Regional Coordinator: [email protected]