Plodia interpunctella (Hubner, 1813) - Indian Meal Moth

Summary

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.

Common Names

Indian meal moth, mealworm moth

Synonyms

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, [1813]; Tinea zeae Fitch, 1856; Unadilla latercula Hampson, 1901

Taxonomic Position

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

Origin and Distribution

The Indian meal moth originated inAsia but is now found in stored products and food storage facilities in a wide range of climates around the world.

Description

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.

Similar Species

Larvae resemble the larvae of Cadra cautella. The adult is distinctive from other moths infesting stored grain.

Life Cycle

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.

Pest Destructive Stage

Larva

Host Range

This species can infest all types of dried food such as grain products, seeds, dried fruit, dog food and spices.

Host Lifestage Affected

Post-harvest

Host Plant Part Affected

seeds and grain

Damage Symptoms

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. 

Pest Management

Detection methods

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.

Cultural practices

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.

 

Physical control

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.

Biological control

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 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
Numerous 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.

Sources of Information and Links

Arthur F.H., Highland H.A. and Mullen M.A. (1991). Efficiency and longevity of two commercial sex pheromone lures for Indian meal moth and almond moth (Lepidoptera: Pyralidae). Journal of Economic Entomology 26: 64-68.

Arthur F. (1989). Pest of stored peanuts: toxicity and persistence of chlorpyrifos-methyl. Journal of Economic Entomology 82: 660-664.

Arthur F, Halliday W.R. and Zettler J.L. (1988). Insecticide resistance among populations of almond moth and Indian meal moth (Lepidoptera: Pyralidae) in stored peanuts. Journal of Economic Entomology 81: 1283-1287.

Arthur F.H., Simonaitis R.A., Throne J.E. and Zehner J.M. (1990). Evaluation of chlorpyrifos-methyl and chlorpyrifos-methyl plus methoprene as protectants of stored corn: small bin tests. Journal of Economic Entomology 83: 1114-1121.

Beeman R.W. and McGaughey W,H. (1988). Resistance to Bacillus thuringiensis in colonies of Indianmeal moth and almond moth (Lepidoptera: Pyralidae). Journal of Economic Entomology 81: 28-33.

Bongers A.J., Brandi D.G., Hinsch R.T., Hoogendorn H. and Soderstrom E.L. (1987). Detecting adult Phyctinae (Lepidoptera: Pyralidae) infestations in a raisin-marketing channel. Journal of Economic Entomology 80: 1229-1232.

Brower J.H. (1988). Population suppression of the almond moth and the Indian meal moth (Lepidoptera: Pyralidae) by release of Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) into simulated peanut storages. Journal of Economic Entomology 81: 944-948.

Brower J.H. and Press J.W. (1990). Interaction of Bracon hebetor (Hymenoptera: Braconidae) and Trichogramma pretosium (Hymenoptera: Trichogrammatidae) in suppressing stored-product moth populations in small in-shell peanut storages. Journal of Economic Entomology 83: 1096-1101.

Dowdy A.K., Hagstrum D.W. and Lippert G.E. (1994). Early detection of insects in stored wheat using sticky traps in bin headspace and prediction of infestation level. Environmental Entomology 23: 1241-1244.

McGaughey W.H. and Tabashnik B.E. (1994). Resistance risk assessment for single and multiple insecticides: responses of Indian meal moth (Lepidoptera: Pyralidae) to Bacillus thuringiensis. Journal of Economic Entomology 87: 834-841.

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.

Smith E.H. and Whitman R.C. (1992). Field Guide to Structural Pests. National Pest Management Association, Dunn Loring, VA.

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