Many, see text
The Indian mealmoth (Plodia interpunctella), alternatively spelled Indianmeal moth, is a pyraloid moth of the family Pyralidae. Alternative common names are weevil moth, pantry moth, flour moth, or grain moth. The almond moth (Cadra cautella) and the raisin moth (Cadra figulilella) are commonly confused with the Indian mealmoth due to similar food source and appearance. It is also not to be confused with the Mediterranean flour moth, another common pest of stored grains.
P. interpunctella larvae (caterpillars) are commonly known as waxworms, though they are not the particular waxworms often bred as animal feed. They are a common grain-feeding pest found around the world, feeding on cereals and similar products. Substantial efforts have been taken in the United States to control the moth's damage to grain crops.
The larvae of the Indian mealmoth has the ability to bite through plastic and cardboard. Thus, even sealed containers may be infested. Once found, the moths are difficult to eradicate. The last instar larvae are can travel long distances before they pupate. Thus, the source of the infestation may not be located near pupation sites and can be far from their surroundings.
- 1 Distribution and habitat
- 2 Taxonomy and etymology
- 3 Description
- 4 Food resources
- 5 Life history
- 6 Enemies
- 7 Mating
- 8 Pest status and pest control
- 9 References
- 10 External links
Distribution and habitat
Plodia interpunctella has been found on every continent, excluding Antarctica. Within America, the moth is most commonly found in Florida, where it thrives in the tropical habitat. The moth lives in a wide range of conditions, making it a persistent pest. It is often found at food storage facilities worldwide, specifically, in grain bins or grain storage buildings .
Taxonomy and etymology
The Indian mealmoth is the only known living species of the genus Plodia. It is closely related to the (doubtfully distinct) genera Cadra and Ephestia which include other pest species like E. kuehniella, which is colloquially called the "flour moth".
- Ephestia glycinivora Matsumura, 1917
- Ephestia glycinivorella Matsumura, 1932 (unjustified emendation)
- 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
The common name for this species was coined by Asa Fitch, an entomologist employed by the state of New York in the 19th century. In a report published in 1856, Fitch discussed the species, noting the larvae infest stores of cornmeal, which was then called "Indian meal".
Adults are 8–10 mm in length with 16– to 20-mm wingspans (c. 3⁄4 of an inch). The distal two-thirds of their forewings are generally reddish brown with a copper luster. They can also be bronze or dark gray. The more proximal parts of the wings are yellow gray or white gray, with a dark band at the intersection between the proximal and distal regions. The hindwings are normally uniformly gray.
The eggs of the Indian mealmoth are white, ovate, and very small. It is difficult to see them with the naked eye. Newly-hatched larvae are equally difficult to see. They are off-white with brown heads and develop through five to seven larval instars. When these larvae mature, they measure to about 12 to 14 mm long. Larvae also have three sets of legs near the head and five sets of prolegs protruding from the abdomen. The legs help the larvae move over long distances in order to find pupation sites.
Indian mealmoths feed on a large range of plants, grains, and other human food products.
Moths feed on many plant-based foods. These foods include dry pet food (plant based), birdseed, cereal, soup mixes, bread, pasta, rice, flour, spices, dried fruits and nuts. There is strong evidence that the northern Manitoba wheat supports the speeding up of development. Other optimal diets include sultanas, American yellow corn and almonds. Groundnuts and maize meal, on the other hand, result in a longer development time for the moths.
Indian mealmoths are also known to cannibalize larvae. However, this often leads to viral granulosis infections spreading through an Indian mealmoth population, even though healthy larvae are picked more often than unhealthy larvae for cannibalism. Typically cannibals do not eat closely related individuals who might share genetic traits with them, but when given the choice between siblings and unrelated individuals, mealmoths tend to cannibalize their siblings.
Though Indian mealmoths do not undergo whole scale migration over long distances, they do engage in long distance foraging flights. These flights take place during the twilight hours during which blue light (400 to 475 nm) rather than UV light (10 to 400 nm) is dominant and attracts the moths. To add to this, blue light's role in the Indian mealmoth foraging behavior has recently been developed as a form pest control since it is attractive to the moth.
Usually, the life cycle of an Indian mealmoth colony starts in a location where grain is present. The temperature within a grain bin must exceed fifty degrees Fahrenheit (10 °C). The eggs of the moth are grayish white and have a length between 0.3 and 0.5 mm. Eggs can be laid directly on the food source either singly or in groups of between 12 and 30. A mature female may lay between 100 and 300 eggs at a time.
Larvae begin to hatch in approximately two to fourteen days. The larvae have between five and seven instars. Newly-hatched larvae feed on grain while more mature larvae feed on grain germ. The larvae are an off-white color, but can be pink, brown, or greenish. They are about 12 mm long and have prolegs for movement purposes. Fully-grown larvae will spin a web and leave silk threads in their path of travel.
Mature larvae make silk threaded cocoons. The pupae are often seen on grain surfaces and on the walls of grain bins. The adults emerge in four to ten days. They then mate and the cycle begins again. The entire life cycle of this species may take 30 to 300 days. A typical life cycle takes 50 days. Under optimal conditions a life cycle can be as short as 28 days but cooler winter months prohibit this from happening. There is a potential for seven to nine generations of moths to live in a year .
Diapause is defined as a delay in animal development due to certain external factors. It can end once the adverse environmental conditions wear off. This kind of behavior is witnessed in Indian mealmoths. It is especially prevalent late in the breeding season. During the egg stage, if the temperature of the moth's environment exceeds 25 degrees Celsius (77 °F), it can cause a delay in hatching. Additionally, in the moth's early larval stage, temperatures of below 20 degrees Celsius (68 °F) can cause a similar diapause. Different strains of Plodia interpunctella have differing tendencies to enter diapause.
Larva on sprinkles
- Nocturnal insectivores: birds, bats, and owls
- Lizards (Lacertilia)
- Bears (Ursidae)
- Cats (Felis catus)
- Dogs (Canis lupus familiaris)
- Rodents (Rodentia)
- Other cannibalistic Indian mealmoths
- Habrobracon hebetor is a parasitoid wasp that is commonly used in biological control. The gut enzymes that are released by this parasite into the Indian mealmoth larvae denature blood proteins. This leads to the death of the moth.
- Baculoviruses are double-stranded DNA viruses which are commonly used as biological control agents for the Indian mealmoth and are considered parasites. They come from a family of viruses that are limited to insects as hosts. Baculovirus isolates have been often isolated from other Lepidoptera. At sub-lethal dosages, baculoviruses decrease reproductive capacity in terms of egg viability and production.
Indian mealmoths are gradually developing resistance to Bacillus thuringiensis, a Gram-positive bacterium which lives in the soil and is widely used as a biological pesticide, among other pesticides. Since there are regulations preventing the use of many pesticides near food sources, these pests are highly suitable for control with natural predators.
Indian mealmoths are also developing a resistance to many kinds of biological agents that are used such as the granulosis virus. Use of such pest control agents can cause the resistance to these agents to be selected for in populations of Indian mealmoths. In populations that were exposed to the granulosis virus, it was found that the moths were 96 times more resistant to the virus. This led to the prohibition of many such biological agents.
Females of the species mate multiple times, meaning sperm competition is an important aspect of male-male competition for being reproductively successful. Additionally, males have a very limited number of sperm and therefore allocate it depending on various factors. Male Indian mealmoths ejaculate a greater amount of sperm to females that had previously mated multiple times. This is predicted to ensure a greater chance of success in sperm competition in the females' storage organs. Males also ejaculate more sperm when mating with a younger female.
Food and pupation site competition
The most common type of competition in Indian mealmoths is due to a lack of sufficient food. This competition can change the timing of male and female emergence reducing the chance of early males finding females to mate with, which could encourage emigration. This is considered a form of male-male competition because the males that emerge at an appropriate time are more likely to be reproductively successful with the surrounding females.
Males are also involved in finding pupation sites. If the larvae do not find pupation sites in the food layer, they may wander long distances to find one. Though this competition to find a pupation site affects males more than it does females, it indirectly impacts them as well because it results in a delayed population of males to mate with.
In the Indian mealmoth, mating occurs a few days after the adult moth emerges from the silk cocoon. Mating rituals are largely limited to pheromones release by the female. There are four primary pheromones that have been identified (via mass spectrometry techniques) in the female pheromone blend: (Z,E)-9,12-tetradecadienyl acetate, (Z,E)-9,12-tetradecadienal, (Z,E)-9,12-tetradecadienol, and (Z)-9-tetradecenyl acetate. The pheromone is an attractant to male Indian mealmoths. Removing any one component of the blend reduces the activity of the pheromone and the number of males attracted. Though other components of the pheromone blend are also known, their functions are unclear. It has been suggested that the reason for having so many components to the pheromone is that it ensures species specificity.
Male Indian mealmoths also release pheromones. After approaching the female from the back, the male releases a pheromone from wing glands which are located at the base of each forewing. These pheromones induce the female to remain stationary in the acceptance posture (raised abdomen between wings) which facilitates copulation.
Copulation and multiple mating
Indian mealmoths are known to mate multiple times. For males, it is vital to ensure paternity after copulation. To ensure this trait, males who mate with a female first (before any other males) will insert a large package of spermatophore, accessory gland fluids, and nutrients into the bursa copulatrix of the female during copulation. Other donations after the first mating are smaller in size. Even so, there is no change in postcopulatory behavior in females after this large donation (with respect to pheromone production and calling behavior).
Changes in fecundity
It has been observed in many insects that vital resources are tracked using odor plumes. However, for the Indian meal moth, such odors have other effects as well. The Indian mealmoth's fecundity and fertility was found to be enhanced in the presence of the odor of vital nutrients. This effect is thought the be genetic since it is not related to parental generations or previous experiences in the lifetime of the moth. Females also show a strong preference towards laying their batches of eggs near the site of the odor. It was observed that without antennae, this effect is lost, suggesting that there are olfactory receptors in the antennae.
The Indian mealmoth often takes part in interspecific courtship especially with the almond moth (Cadra cautella). However, successful mating between the species does not happen due to multiple isolation mechanisms. The main mechanism that has been identified is the male sex pheromone. This pheromone is a strong species recognition signal. It allows the almond moth to differentiate between members of its own species and members of the Indian mealmoth species. There are also mechanical barriers to insemination that render the species incompatible. Their courtship behaviors are also relatively incompatible. Thus, copulation rarely occurs.
Even when courtship does continue to a later stage, the female of the other species rejects the male due to the wrong pheromone being released at the wrong time from scent scales. Even with these fail safes, some male almond moths are still excited by Indian mealmoth females. They may be able to successfully copulate, but insemination is not possible.
Pest status and pest control
Indian mealmoth larvae can infest a wide range of dry foodstuffs of vegetable origin, such as cereal, bread, pasta, rice, couscous, flour, spices, dried fruits, and nuts. More unusual recorded foods include crushed red pepper, chocolate and cocoa beans, coffee substitute, cookies, dried mangelwurzel, and even the toxic seeds of jimsonweed (Datura stramonium). They have also been known to infest commercial pet food, such as cracked corn used for bird feed. They often leave webbing in the food they infest.
After larvae or moths have been found, it is important to throw out all food sources not in very tightly sealed containers. Moth larvae can chew through plastic bags and thin cardboard, so even unopened packages may become infested. They are also notoriously difficult to get rid of, and can crawl on ceilings and spin cocoons in rooms other than the kitchen or pantry where they hatched. Last instar larvae are able to travel significant distances before they pupate. When seeking the source of an infestation, the search thus cannot be limited to the immediate area where pupae are discovered.
None of the stages of the organism (eggs, larvae, adults) are very temperature tolerant and all can be killed by a week of freezing or by brief heating in a microwave or conventional oven when such treatment is practical. Scrubbing infested areas with a mixture of soap and water or vinegar is also effective.
Nontoxic traps are also available to monitor outbreaks. One type of trap is a triangular box with a pheromone lure and sticky walls inside. These traps are generally known as pheromone traps. In this case, male moths are attracted inside by the female pheromone (the lure) and then get stuck against the sticky walls inside the box.
Moths often do not even need a lure, as common glue traps sometimes work well to reduce the number of adults. However, the efficiency of such traps is highly doubtful as they only capture males, and usually only a fraction of them, while adult females, eggs and larvae are unaffected, enabling a possible reinfestation. Moths can be deterred from an area by using essential oils and nontoxic pantry moth spray. It is most effective to treat the infestation by eliminating the source and any affected food items, interrupting their mating processes, and repelling them from the areas where dried food and grains are kept. Thus it is recommended to first eliminate the source of infestation followed by larvae, eggs, and eventually moths.
Additionally, blue to violet light can be very effective in drawing moths, which suggests that the deployment of violet light could become yet another pest control tactic for Indian mealmoths.
- "Indian Meal Moth (Department of Entomology)". Department of Entomology (Penn State University). Retrieved 2 October 2017.
- "National Pesticide Information Centre". Retrieved 1 September 2016.
- Fasulo, Thomas R. & Knox, Marie A. (2009): University of Florida Featured Creatures – Indianmeal moth, Plodia interpunctella Hübner. Version of December 2009.
- Mohandass, S; Arthur, F; Zhu, K; Throne, J (2007). "Biology and management of Plodia interpunctella (Lepidoptera: Pyralidae) in stored products" (webpage). Journal of Stored Products Research. Manhattan, Kansas, United States of America: Elsevier. 43 (3): 302–311. doi:10.1016/j.jspr.2006.08.002. ISSN 0022-474X. Retrieved 10 November 2017.
- Fasulo, Thomas; Knox, Marie (November 2015). "indianmeal moth". Featured Creatures. university of Florida. Retrieved 10 November 2017.
- Horak, M. (1994). "A Review of Cadra Walker in Australia: Five New Native Species and the Two Introduced Pest Species (Lepidoptera: Pyralidae: Phycitinae)". Australian Journal of Entomology. 33 (3): 245. doi:10.1111/j.1440-6055.1994.tb01226.x.
- References in Savela, Markku (2009): Markku Savela's Lepidoptera and Some Other Life Forms – Plodia. Version of 9 April 2010. Retrieved 10 April 2010.
- Fitch, Asa (1856) First and Second Report on the Noxious, Beneficial and other Insects of the State of New York. C. Van Benthuysen, Albany, USA.
- Lyon, William F. (2006): Ohio State University Insect and Pest Fact Sheets – HYG-2089-97: Indianmeal Moth. Version of 31 August 2006.
- Williams, Gwyneth (June 1964). "The life-history of the Indian meal-moth, Plodia interpunctella (Hübner) (Lep. Phycitidae) in a warehouse in Britain and on different foods". The Annals of Applied Biology. 53 (3): 459–475. doi:10.1111/j.1744-7348.1964.tb07259.x. Retrieved 25 September 2017.
- Boots, Michael (1 May 1998). "Cannibalism and the stage-dependent transmission of a viral pathogen of the Indian meal moth, Plodia interpunctella". Ecological Entomology. 23 (2): 118–122. doi:10.1046/j.1365-2311.1998.00115.x. ISSN 1365-2311.
- Boots, M. "Kinship and cannibalism in the Indian meal moth, Plodia interpunctella: No evidence of kin discrimination". Evolutionary Ecology Research. 2: 119–128.
- Cowan, Thomas; Gries, Gerhard (1 May 2009). "Ultraviolet and violet light: attractive orientation cues for the Indian meal moth, Plodia interpunctella". Entomologia Experimentalis et Applicata. 131 (2): 148–158. doi:10.1111/j.1570-7458.2009.00838.x. ISSN 1570-7458.
- Frederick), Chapman, R. F. (Reginald (1998). The insects : structure and function (4th ed.). Cambridge, UK: Cambridge University Press. ISBN 0521570484. OCLC 37682660.
- Tzanakakis, M. E. (1 November 1959). "An ecological study of the Indian-meal moth Plodia interpunctella (Hübner) with emphasis on diapause". Hilgardia. 29 (5): 205–246. doi:10.3733/hilg.v29n05p205. ISSN 0073-2230.
- "Biological Control of Stored-Product Pests" Midwest Biological Control News (University of Wisconsin)
- Sait, Begon (July 1994). "The Effects of a Sublethal Baculovirus Infection in the Indian Meal Moth, Plodia interpunctella". Journal of Animal Ecology. 63 (3): 541–550. doi:10.2307/5220. Retrieved 25 September 2017.
- McGaughey, W. H.; Beeman, R. W. (February 1988). "Resistance to Bacillus thuringiensis in Colonies of Indianmeal Moth and Almond Moth (Lepidoptera: Pyralidae)". Journal of Economic Entomology. 81 (1): Pages 28–33. Retrieved 25 September 2017.
- du Rand, Nicolette (July 2009). Isolation of Entomopathogenic Gram Positive Spore Forming Bacteria Effective Against Coleoptera (PhD thesis). Pietermaritzburg, South Africa: University of KwaZulu-Natal. hdl:10413/1235.[page needed]
- Boots, M.; Begon, M. (1993). "Trade-Offs with Resistance to a Granulosis Virus in the Indian Meal Moth, Examined by a Laboratory Evolution Experiment". Functional Ecology. 7 (5): 528–534. doi:10.2307/2390128.
- Cook, Penny A.; Gage, Matthew J. G. (1995). "Effects of Risks of Sperm Competition on the Numbers of Eupyrene and Apyrene Sperm Ejaculated by the Moth Plodia interpunctella (Lepidoptera: Pyralidae)". Behavioral Ecology and Sociobiology. 36 (4): 261–268. doi:10.2307/4601073. Retrieved 30 September 2017.
- Podoler, H. (1974). "Effects of Intraspecific Competition in the Indian Meal-Moth (Plodia interpunctella Hubner) (Lepidoptera: Phycitidae) on Populations of the Moth and its Parasite Nemeritis canescens (Gravenhorst) (Hymenoptera: Ichneumonidae)". Journal of Animal Ecology. 43 (3): 641–651. doi:10.2307/3528.
- Zhu, Junwei; Rikard Unelius, C.; Ryne, Camilla; Valeur, Peter G.; Löfstedt, Christer (August 1999). "Reidentification of the female sex pheromone of the Indian meal moth, Plodia interpunctella: evidence for a four-component pheromone blend". Entomologia Experimentalis et Applicata. 92 (2): Pages 137–146. doi:10.1046/j.1570-7458.1999.00533.x. Retrieved 25 September 2017.
- Grant, G. G.; Brady, U. E. (1 June 1975). "Courtship behavior of phycitid moths. I. Comparison of Plodia interpunctella and Cadra cautella and role of male scent glands". Canadian Journal of Zoology. 53 (6): 813–826. doi:10.1139/z75-095. ISSN 0008-4301.
- Ryne, Camilla; Zhu, Jun-Wei; Van Dongen, Stefan; Christer, Löfstedt (2001). "Spermatophore Size and Multiple Mating: Effects on Reproductive Success and Post-Mating Behaviour in the Indian Meal Moth". Behaviour. 138 (8): 947–963. doi:10.1163/156853901753286506. Retrieved 30 September 2017.
- Cardé, Ring T.; Willis, Mark A. (1 July 2008). "Navigational Strategies Used by Insects to Find Distant, Wind-Borne Sources of Odor". Journal of Chemical Ecology. 34 (7): 854–866. doi:10.1007/s10886-008-9484-5. ISSN 0098-0331.
- Deseő, K.V. (1 January 1976). "The Oviposition of the Indian Meal Moth (Plodia Interpunctella Hbn., Lep., Phyticidae) Influenced by Olfactory Stimuli and Antennectomy". The Host-Plant in Relation to Insect Behaviour and Reproduction. Springer US: 61–65. Retrieved 2 October 2017.
- Grant, G. G.; Smithwick, E. B.; Brady, U. E. (1 June 1975). "Courtship behavior of phycitid moths. II. Behavioral and pheromonal isolation of Plodia interpunctella and Cadra cautella in the laboratory". Canadian Journal of Zoology. 53 (6): 827–832. doi:10.1139/z75-096. ISSN 0008-4301.
- Grabe, Albert (1942): Eigenartige Geschmacksrichtungen bei Kleinschmetterlingsraupen ["Strange tastes among micromoth caterpillars"]. Zeitschrift des Wiener Entomologen-Vereins 27: 105–109 [in German]. PDF fulltext
- "How to Get Rid of Pantry Moths". Learn to Get Rid Of... 19 February 2015. Retrieved 27 March 2015.
- Klass, Carolyn (2009) Pesticide Management Education Program – Indian Meal Moth. Version of February 2009.
- Cranshaw, Whitney (2011): Indian Meal Moth. Colorado State University Extension. Version 4/03. Reviewed 3/08.
- Phillips, Tom (1995) Biological Control of Stored-Product Pests Archived 15 June 2010 at the Wayback Machine.. Midwest Biological Control News Online 2(10).
|Wikimedia Commons has media related to Plodia interpunctella.|
- Indian Meal Moth Fact Sheet featuring information on habits, habitat and pictures
- Scarabogram Bug of the Month: Indianmeal Moth
- Home and Garden: Indianmeal Moth
- OzAnimals – Indianmeal Moth
- University of California Integrated Pest Management: – Pantry Pests