Mealworm

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Mealworm
Temporal range: Holocene, 0.003–0 Ma
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Infraorder: Cucujiformia
Family: Tenebrionidae
Genus: Tenebrio
Species:
T. molitor
Binomial name
Tenebrio molitor
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 1.25 to 1.8 centimetres (0.49 to 0.71 in) in length.

The yellow mealworm beetle prefers a warmer climate and higher humidity.[1] T. molitor is dark brown or black as an adult,[2] with larvae up to 1.25 inches (3.2 cm) long and adults up to 0.75 inches (1.9 cm) long.[3]

Description

The yellow mealworm beetle can be differentiated from other beetles due to the linear grooves that run along the abdomen. The grooves are evenly divided. In addition, the beetle has only four tarsal segments on its hind legs. Most ground beetles, which are similar in size to Tenebrio molitor, have five tarsal segments.[2]

Commonly mistaken with the black mealworm beetle (T. obscurus), key variations in regard to size and shape distinguish these two. The abdomen of the adult black mealworm beetle is more rounded and ends in a pointed tip, as opposed to the more rectangular and blunt-ended abdomen of the yellow mealworm beetle.[2] Additionally, the larvae of T. molitor are lighter colored than those of T. obscurus.[3]

Distribution

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.[4]

Reproduction

Tenebrio molitor larvae eating an apple slice

A sex pheromone released by male mealworms has been identified.[5] Inbreeding reduces the attractiveness of sexual pheromone signaling by male mealworms.[6] 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.[7]

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 adult lifespan of about 6-12 months, a female will, on average, lay about 500 eggs.[8]

After 4 to 19 days the eggs hatch.[8]

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.[8]

Mate choice

Researchers examined whether female beetles preferred noninfected or infected males as mates. Virgin females were found to spend more time near and copulated more often with noninfected males in the experiment. Mating behavior was also found to be influenced by the mass of the male beetle. A larger male was preferred and mated with first compared to a smaller male mate. Overall, female beetles showed mating preferences for noninfected males who were larger in size. One explanation provided by researchers for this findings is that noninfected males who are larger may allow females to gain genetic or material benefits. [9]

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] Mealworms have generally been considered pests, because they feed on stored grains.

As feed and pet food

Mealworms are typically used as a pet food for captive reptiles, fish, birds, and some small mammals. 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.[10]

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.[11]

As food

Mealworms in a bowl

Mealworms are edible for humans, and processed into several insect food items available in food retail such as insect burgers.[12]

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.[13]

In May 2017, mealworms were approved as food in Switzerland.[14] In June 2021, dried mealworms were authorized as novel food in the European Union,[15] after the European Food Safety Authority assessed the larvae as safe for human consumption.[16][17]

Mealworm larvae contain significant nutrient content.[10] For every 100 grams of raw mealworm larvae, 206 kilocalories and anywhere from 14 to 25 grams of protein are contained.[18] Mealworm larvae contain levels of potassium, copper, sodium, selenium, iron and zinc that rival those of beef. Mealworms contain essential linoleic acids as well. They also have greater vitamin content by weight compared to beef, B12 not included.[18][19]

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.[20]

In waste disposal

In 2015, it was discovered that 100 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.[21] Microorganisms inside the mealworm's gut are responsible for degrading the polystyrene, with mealworms given the antibiotic gentamicin showing no signs of degradation.[22] Isolated colonies of the mealworm's gut microbes, however, have proven less efficient at degradation than the bacteria within the gut.[22]

See also

  • Zond 5, a 1968 space mission on which mealworms were among the first terrestrial organisms to travel to and circle the Moon[23]
  • Plastivore

Gallery

References

  1. ^ Punzo, Fred; Mutchmor, J. A. (1980). "Effects of Temperature, Relative Humidity and Period of Exposure on the Survival Capacity of Tenebrio molitor (Coleoptera: Tenebrionidae)". Journal of the Kansas Entomological Society. 53 (2): 260–270. ISSN 0022-8567. JSTOR 25084029.
  2. ^ a b c Melms, David (Spring 2010). "Mealworm Beetle". Katharine Ordway Natural History Study Area. Macalester College. Retrieved 2024-03-20.
  3. ^ a b Bennett, Stuart M. (2003). "Tenebrio molitor (Yellow Mealworm Beetle)". Stored Product Insects. Retrieved 2024-03-20.
  4. ^ Panagiotakopulu E (2001). "New records for ancient pests: archaeoentomology in Egypt". Journal of Archaeological Science. 28 (11): 1235–1246. Bibcode:2001JArSc..28.1235P. doi:10.1006/jasc.2001.0697.
  5. ^ 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.
  6. ^ 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.
  7. ^ Bernstein H, Hopf FA, Michod RE (1987). "The Molecular Basis of the Evolution of Sex". In Scandalios JG, Caspari EW (eds.). Molecular Genetics of Development. Advances in Genetics. Vol. 24. Academic Press, Inc. pp. 323–370. doi:10.1016/S0065-2660(08)60012-7. ISBN 0-12-017624-6. PMID 3324702.
  8. ^ a b c "Mealworm Beetle". Retrieved 2022-09-25.
  9. ^ Worden, Bradley D.; Parker, Patricia G. (November 2005). "Females prefer noninfected males as mates in the grain beetle Tenebrio molitor: evidence in pre- and postcopulatory behaviours". Animal Behaviour. 70 (5): 1047–1053.
  10. ^ 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.
  11. ^ Finke, M.; Winn, D. (2004). "Insects and related arthropods: A nutritional primer for rehabilitators". Journal of Wildlife Rehabilitation. 27: 14–17.
  12. ^ Ledsom, Alex (13 January 2021). "Insect Market To Explode: EU Gives Green Light To Eating Mealworm". Forbes.
  13. ^ 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.
  14. ^ "Insects as food" (in German). Bundesamt für Lebensmittelsicherheit und Veterinärwesen. 2017-04-28.
  15. ^ "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.
  16. ^ 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.
  17. ^ 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.
  18. ^ 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–.
  19. ^ 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.
  20. ^ 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.
  21. ^ Jordan, Rob (29 September 2015). "Plastic-eating worms may offer solution to mounting waste, Stanford researchers discover". Stanford News Service. Archived from the original on 20 February 2021. Retrieved 24 March 2016.
  22. ^ a b Lockwood, Deirdre (September 30, 2015). "Mealworms Munch Polystyrene Foam". Chemical and Engineering News. Retrieved 2019-02-04.
  23. ^ Madigral, Alexis C. (27 December 2012). "Who Was First in the Race to the Moon? The Tortoise". Atlantic. Retrieved 9 March 2019.

External links