Mealworm
Temporal range: Holocene, 0.003–0 Ma
Tenebrio molitor Linné, 1758 (32842137535).png
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Tenebrionidae
Genus: Tenebrio
Species:
T. molitor
Binomial name
Tenebrio molitor
Mealworms (larvae of Tenebrio molitor) illustrated by Des Helmore
Mealworms (larvae of Tenebrio molitor) illustrated by Des Helmore

Mealworms are the larval form of the yellow mealworm beetle, Tenebrio molitor, a species of darkling beetle. Like all holometabolic insects, they go through four life stages: egg, larva, pupa, and adult. Larvae typically measure about 2.5 centimetres (0.98 in) or more, whereas adults are generally between 1.25 to 1.8 centimetres (0.49 to 0.71 in) in length.

Reproduction

Tenebrio molitor larvae eating an apple slice

The mealworm beetle breeds prolifically. Males insert sperm packets with their aedeagus. Within a few days the female burrows into soft ground and lays eggs. Over her lifespan, a female will, on average, lay about 500 eggs.[1]

After 4 to 19 days the eggs hatch.[1]

During the larval stage, the mealworms feed on vegetation and dead insects and molt between each larval stage, or instar (9 to 20 instars). After the final molt, they pupate. The new pupa is whitish and turns brown over time. After 3 to 30 days, depending on environmental conditions such as temperature, it emerges as an adult beetle.[1]

Sex pheromones

A sex pheromone released by male mealworms has been identified.[2] Inbreeding reduces the attractiveness of sexual pheromone signaling by male mealworms.[3] Females are more attracted to the odors produced by outbred males than the odors produced by inbred males. The reduction of male signaling capability may be due to increased expression of homozygous deleterious recessive alleles caused by inbreeding.[4]

Relationship with humans

Tenebrio molitor is often used for biological research. Its relatively large size, ease of rearing and handling, and status as a non-model organism make it useful in proof of concept studies in the fields of basic biology, biochemistry, evolution, immunology and physiology.[citation needed]

As pests

Mealworms have generally been considered pests, because they feed on stored grains. Mealworms probably originated in the Mediterranean region, but are now present in many areas of the world as a result of human trade and colonization. The oldest archaeological records of mealworms can be traced to Bronze Age Turkey. Records from the British Isles and northern Europe are from a later date, and mealworms are conspicuously absent from archaeological finds from ancient Egypt.[5]

As feed and pet food

Main articles: Insects as feed and Insect based pet food

Mealworms are typically used as a pet food for captive reptiles, fish, and birds. They are also provided to wild birds in bird feeders, particularly during the nesting season. Mealworms are useful for their high protein content. They are also used as fishing bait.[6]

They are commercially available in bulk and are typically available in containers with bran or oatmeal for food. Commercial growers incorporate a juvenile hormone into the feeding process to keep the mealworm in the larval stage and achieve an abnormal length of 2 cm or greater.[7]

As food

Main articles: Insects as food and Entomophagy in humans

Mealworms in a bowl
Mealworms in a bowl

Mealworms are edible for humans, and processed into several insect food items available in food retail such as insect burgers.[8]

Mealworms have historically been consumed in many Asian countries, particularly in Southeast Asia. There, they are commonly found in food markets and sold as street food alongside other edible insects. Baked or fried mealworms have been marketed as a healthy snack food in recent history, though the consumption of mealworms goes back centuries.[9]

In May 2017, mealworms were approved as food in Switzerland.[10] In June 2021, dried mealworms were authorized as novel food in the European Union,[11] after the European Food Safety Authority assessed the larvae as safe for human consumption.[12][13]

Mealworm larvae contain significant nutrient content.[6] For every 100 grams of raw mealworm larvae, 206 kilocalories and anywhere from 14 to 25 grams of protein are contained.[14] Mealworm larvae contain levels of potassium, copper, sodium, selenium, iron and zinc that rival that of beef. Mealworms contain essential linoleic acids as well. They also have greater vitamin content by weight compared to beef, B12 not included.[14][15]

Mealworms may be easily reared on fresh oats, wheat bran or grain, with sliced potato, carrots, or apple as a moisture source. The small amount of space required to raise mealworms has made them relevant for scalable industrialized mass production.[16]

In waste disposal

In 2015, it was discovered that mealworms can degrade polystyrene into usable organic matter at a rate of about 34–39 milligrams per day. Additionally, no difference was found between mealworms fed only Styrofoam and the mealworms fed conventional foods, during the one-month duration of the experiment.[17] Microorganisms inside the mealworm's gut are responsible for degrading the polystyrene, with mealworms given the antibiotic gentamicin showing no signs of degradation.[18] Isolated colonies of the mealworm's gut microbes, however, have proven less efficient at degradation than the bacteria within the gut.[18]

See also

Gallery

  • In a bedding of bran
    In a bedding of bran
  • Mealworm detail
    Mealworm detail
  • A mealworm pupa with molted larval skin
    A mealworm pupa with molted larval skin
  • New adult
    New adult
  • Mature adult
    Mature adult

References

  1. ^ a b c "Mealworm Beetle". Retrieved 2022-09-25.
  2. ^ Bryning GP, Chambers J, Wakefield ME (2005). "Identification of a sex pheromone from male yellow mealworm beetles, Tenebrio molitor". Journal of Chemical Ecology. 31 (11): 2721–30. doi:10.1007/s10886-005-7622-x. PMID 16273437. S2CID 28709218.
  3. ^ Pölkki M, Krams I, Kangassalo K, Rantala MJ (2012). "Inbreeding affects sexual signalling in males but not females of Tenebrio molitor". Biology Letters. 8 (3): 423–5. doi:10.1098/rsbl.2011.1135. PMC 3367757. PMID 22237501.
  4. ^ Bernstein H, Hopf FA, Michod RE (1987). "The molecular basis of the evolution of sex". Molecular Genetics of Development. Advances in Genetics. Vol. 24. pp. 323–70. doi:10.1016/S0065-2660(08)60012-7. ISBN 978-0-12-017624-3. PMID 3324702.
  5. ^ Panagiotakopulu E (2001). "New records for ancient pests: archaeoentomology in Egypt". Journal of Archaeological Science. 28 (11): 1235–1246. doi:10.1006/jasc.2001.0697.
  6. ^ a b Ravzanaadii, Nergui; Kim, Seong-Hyun; Choi, Won-Ho; Hong, Seong-Jin; Kim, Nam-Jung (2012-09-30). "Nutritional Value of Mealworm, Tenebrio molitor as Food Source". International Journal of Industrial Entomology. 25 (1): 93–98. doi:10.7852/ijie.2012.25.1.093. ISSN 1598-3579.
  7. ^ Finke, M.; Winn, D. (2004). "Insects and related arthropods: A nutritional primer for rehabilitators". Journal of Wildlife Rehabilitation. 27: 14–17.
  8. ^ Ledsom, Alex (13 January 2021). "Insect Market To Explode: EU Gives Green Light To Eating Mealworm". Forbes.
  9. ^ Master, The Party (2022-06-28). "EDIBLE MEALWORMS: EVERYTHING You Need to Know!". Party Bugs – Seasoned party snacks made from edible insects (crickets and mealworms). Retrieved 2022-09-30.
  10. ^ "Insects as food" (in German). Bundesamt für Lebensmittelsicherheit und Veterinärwesen. 2017-04-28.
  11. ^ "Commission Implementing Regulation (EU) 2021/882 of 1 June 2021 authorising the placing on the market of dried Tenebrio molitor larva as a novel food under Regulation (EU) 2015/2283 of the European Parliament and of the Council, and amending Commission Implementing Regulation (EU) 2017/2470". EU Commission. 2 June 2021.
  12. ^ Turck, Dominique; Castenmiller, Jacqueline; De Henauw, Stefaan; Hirsch‐Ernst, Karen Ildico; Kearney, John; MacIuk, Alexandre; Mangelsdorf, Inge; McArdle, Harry J.; Naska, Androniki; Pelaez, Carmen; Pentieva, Kristina; Siani, Alfonso; Thies, Frank; Tsabouri, Sophia; Vinceti, Marco; Cubadda, Francesco; Frenzel, Thomas; Heinonen, Marina; Marchelli, Rosangela; Neuhäuser‐Berthold, Monika; Poulsen, Morten; Prieto Maradona, Miguel; Schlatter, Josef Rudolf; Van Loveren, Henk; Ververis, Ermolaos; Knutsen, Helle Katrine; Knutsen, H. K. (13 January 2021). "Safety of dried yellow mealworm (Tenebrio molitor larva) as a novel food pursuant to Regulation (EU) 2015/2283]". EFSA Journal. 19 (1): 6343. doi:10.2903/j.efsa.2021.6343. PMC 7805300. PMID 33488808.
  13. ^ Boffey, Daniel (2021-01-13). "Yellow mealworm safe for humans to eat, says EU food safety agency". The Guardian. ISSN 0261-3077. Retrieved 2021-01-15.
  14. ^ a b "6. nutritional value of insects for human consumption" (PDF). Edible insects: future prospects for food and feed security (PDF). FAO FORESTRY PAPER. Vol. 171. FAO. 2013. pp. 67–.
  15. ^ Schmidt, Anatol; Call, Lisa; Macheiner, Lukas; Mayer, Helmut K. (2018). "Determination of vitamin B12 in four edible insect species by immunoaffinity and ultra-high performance liquid chromatography". Food Chemistry. 281: 124–129. doi:10.1016/j.foodchem.2018.12.039. PMID 30658738. S2CID 58651702.
  16. ^ Rumbos, Christos I.; Athanassiou, Christos G. (March 2021). "Insects as Food and Feed: If You Can't Beat Them, Eat Them!'—To the Magnificent Seven and Beyond". Journal of Insect Science. 21 (2): 9. doi:10.1093/jisesa/ieab019. PMC 8023366. PMID 33822126.
  17. ^ Jordan, Rob (29 September 2015). "Plastic-eating worms may offer solution to mounting waste, Stanford researchers discover". Stanford News Service. Stanford News Service. Retrieved 24 March 2016.
  18. ^ a b Lockwood, Deirdre (September 30, 2015). "Mealworms Munch Polystyrene Foam". Chemical and Engineering News. Retrieved 2019-02-04.
  19. ^ Madigral, Alexis C. (27 December 2012). "Who Was First in the Race to the Moon? The Tortoise". Atlantic. Retrieved 9 March 2019.