Flour beetle

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Flour beetle
Flour beetle (Tenebrio molitor)

Flour beetle ( Tenebrio molitor )

Systematics
Class : Insects (Insecta)
Order : Beetle (Coleoptera)
Subordination : Polyphaga
Family : Black beetle (Tenebrionidae)
Genre : Tenebrio
Type : Flour beetle
Scientific name
Tenebrio molitor
Linnaeus , 1758

The meal beetle ( Tenebrio molitor ) is a beetle from the family of black beetles (Tenebrionidae).

Its larvae are known as mealworms because of their worm-like appearance . Beetles and larvae are storage pests ; the larvae are also bred as food insects for terrarium animals and as food insects for human consumption.

features

The beetles grow to be 10 to 18 millimeters long and have a somewhat elongated body. Your head is flat. Shortly after hatching, they are brightly colored, after a short time they are already reddish-brown, gradually becoming darker and finally turning black all over the body. Longitudinal grooves run on the slightly curved upper wings . The underside of the body, legs and antennae are reddish brown in color.

Occurrence

The beetles are spread all over the world and are among the most common culture followers . In the open air, like their larvae, they inhabit sludge , rotting wood and bird nests. They live in flour and other cereal products around people and prefer to stay in dark and warm places.

Way of life

The nocturnal adults feed on grain, flour, baked goods and other substances that contain starch . This is why flour beetles are often found in bakeries, but this does not necessarily have to be an indication of poor hygiene. They also eat other insects and sometimes their own larvae. Since they hide in dark cracks during the day, they draw attention to themselves primarily through the damage that occurs. The beetles can fly, but rarely do so. Like the beetles, the larvae feed primarily on starchy substances, but also cannibally on their own conspecifics. They also consume the stripped skins of the larvae and pupae.

development

During their three to four months of life, the females lay 100 to 150 eggs individually or in small groups, usually in sheltered places. The eggs are sticky, white, about 1.5 millimeters long and oval. Dust and the like adhere to them, which gives them good camouflage. The larvae that hatch are initially about two millimeters long and whitish in color. Their body soon has a golden brown color, after each moult they are light whitish again and only gradually turn golden brown again. They become about 40 millimeters long and pupate in the food substrate.

  • Larva before (above) and after moulting (below)

  • Pupa and newly hatched beetle. In the background you can see the stripped doll skin (Exuvie)

  • Macro shot of a mealworm

  • Mealworms in bran

Use by humans

Mealworms as animal feed

Mealworms are bred as feed insects for insectivorous birds and as bait for anglers . Bat protectors also feed bats in need of care with mealworms. Furthermore, mealworms, their pupae and also the adult beetles are a good source of protein for rodents such as mice , hamsters , lemmings etc. They are eaten alive by many animals. In terrariums, too, mealworms are often fed to lizard species or ants, and the high fat and protein content can quickly lead to overfeeding. Many terrarium owners therefore use mealworms primarily to feed and strengthen their animals.

In addition to the pet and hobby area, mealworms are used in livestock husbandry. Mealworms have been approved in the EU for use as feed in aquaculture since July 2017 .

Mealworms as food

Freeze-dried mealworms as food

The larvae of black beetle species such as flour beetles, large black beetles or grain mold beetles are bred as food insects for human consumption and use in processed foods, in Europe primarily in the Netherlands and Belgium, but also in Germany.

Insect burger made from mealworms

While insects are traditionally used in much of the world as food, they are considered in Europe as novel foods ( Novel Food ) and require approval. In Switzerland , mealworms in the larval stage have been permitted as food since May 1, 2017 - alongside house crickets ( Acheta domesticus ) and European migratory locusts ( Locusta migratoria ). Under certain conditions, they may be given to consumers as whole animals, chopped or ground, for food purposes. In August 2017, the Swiss retailer Coop launched a hamburger patty and meatballs made from mealworms. In the EU, insects as food come under the so-called Novel Food Regulation , which has been in force since January 1, 2018. For insects and processed products made from or with insects, an application for approval must be submitted to the European Commission. The safety is checked by the European Food Safety Authority (EFSA). By March 2020, the EU Commission had received four applications for meal beetles as a food. On January 13, 2021, EFSA published a risk assessment in which it assessed the consumption of mealworms by humans as safe, both as a whole dried insect and in powder form. On May 4, 2021, the EU countries confirmed their approval to the EU Commission and released yellow mealworms as the first food insects for consumption. The application for approval was made by a French company that has now had the sole (with exceptions) right to sell this novel food for five years . The mealworms should contribute to a more sustainable food system in the EU. According to the EU Commission, mealworms can be used as a snack or ingredient, for example in protein and pasta products or in biscuits.

Mealworms, like many edible insects, are rich in nutrients, but use fewer resources compared to many types of meat. The larvae can be used as a source of high-quality protein , as can other animal foods from mammals, birds or edible fish . They contain omega-3 fatty acids , are at the same time very low in fat and rich in high-quality proteins (around 45 grams of protein per 100 grams of freeze-dried mealworms) and other nutrients. Ecological reasons are also given as an argument for using mealworms as food. In a study from the University of Wageningen in 2012, for example, mealworms require only 43 percent of the land required for milk to produce one kilogram of edible protein and only ten percent of the land used for beef production . The consumption of mealworms is rated as safe, but can lead to allergic reactions, especially in people with house dust mite allergies or an allergy to crustaceans such as shrimp, which is why allergen labeling must be carried out.

Mealworms as vectors of disease

Mealworms can transmit dwarf tapeworms ( Hymenolepis nana and Hymenolepis diminuta ) to humans. Both types of tapeworm are parasites in the intestines of rats, with faecal arthropods as intermediate hosts. If children in particular accidentally ingest an intermediate host such as the beetle, they can become infected. However, cases are very rare in industrialized nations. Hymenolepis nana can also be transmitted directly from person to person without an intermediate host.

Possible use as a plastic recycler

In 2015, researchers at Stanford University discovered that mealworms are able to consume polystyrene and break it down into CO 2 and rotting feces . A hundred worms consumed 35–39 mg daily. After the month-long experiment, no difference could be found between the health status of mealworms that ate exclusively on polystyrene and those that ate conventional food. The digestive process has not yet been researched in detail.

literature

  • Jiři Zahradník, Irmgard Jung, Dieter Jung: Beetles of Central and Northwestern Europe. Parey, Berlin 1985, ISBN 3-490-27118-1 .
  • Karl G. Lutz (ed.), Edmund Reitter : Fauna Germanica. The beetles of the German Empire. Volume 3. Lutz, Stuttgart 1911, p. 347.
  • Edmund Reitter: Fauna Germanica. The beetles of the German Empire. Directmedia Publishing, Berlin 2006, ISBN 3-89853-534-7 (new sentence and facsimile of the five-volume edition Stuttgart 1908-1916).
  • Folke Dammann, Nadine Kuhlenkamp: The insect cookbook. Kosmos, Stuttgart 2015, ISBN 978-3-440-14846-4
  • Christian Bärtsch, Adrian Kessler: Grilling, Insects & Co. AT Verlag, Aarau 2016, ISBN 978-3-03800-923-8

Web links

Commons : Flour beetle ( Tenebrio molitor )  - Album with pictures, videos and audio files

Individual evidence

  1. ↑ Regulation (EU) 2017/893 of the Commission of 24 May 2017 amending Annexes I and IV of Regulation (EC) No. 999/2001 of the European Parliament and of the Council as well as Annexes X, XIV and XV of the Regulation (EU ) No. 142/2011 of the Commission regarding the provisions on processed animal protein , on eur-lex.europa.eu, accessed on February 18, 2019
  2. ↑ Spiegel Online / Lara Janssen (August 24, 2017): Insects as food: How mealworms got into Swiss burgers .
  3. ^ FSVO (April 28, 2017): Insects as food .
  4. ↑ Horizont / Eva-Maria Schmidt (August 14, 2017): Coop launches insect burger with Essento .
  5. ↑ a b Hamburger Abendblatt / Susanne Zahn (December 27, 2017): Insect Burger for the New Year .
  6. ↑ FAQ on Novel Food. BVL , accessed on January 8, 2018 .
  7. ↑ Meal beetle larvae as food. Insektenwirtschaft.de, accessed on March 20, 2020 .
  8. ↑ Deutschlandfunk Kultur / Daniela Siebert (August 14, 2018): Crickets and worms as food - insect burgers made from beetle larvae .
  9. ↑ EFSA (January 13, 2021): Safety of dried yellow mealworm (Tenebrio molitor larva) as a novel food pursuant to Regulation (EU) 2015/2283 .
  10. ↑ Insektenwirtschaft.de (January 13, 2021): EFSA rates mealworms as food as positive .
  11. ↑ Yellow mealworm approved as a new type of food. However, the Federal Office points out possible allergic reactions. May 4, 2021, accessed May 6, 2021 .
  12. ↑ EU Commission: Approval of first insect as novel food .
  13. ↑ a b Mealworms are now food , Tagesschau, May 4, 2021.
  14. ↑ Federal Center for Nutrition (BZfE) (2017): Insects - (K) an everyday food .
  15. ↑ Der Spiegel / Irene Habich (May 20, 2018): Grilling a barbecue. Insects as an alternative to fish and meat .
  16. ↑ WELT (December 29, 2012): Mealworms better than cattle, pigs and chickens .
  17. ↑ Dennis GAB Oonincx, Imke JM de Boer, Gregory A. Sword: Environmental Impact of the Production of Mealworms as a Protein Source for Humans - A Life Cycle Assessment. In: PLoS ONE. 7, 2012, p. E51145, doi : 10.1371 / journal.pone.0051145 .
  18. ↑ Myrna Apel: The allergy potential of edible insects should not be underestimated. April 17, 2018, accessed on March 10, 2020 (German).
  19. ↑ Henrike Broekman, Kitty C. Verhoeckx, Constance F. den Hartog Jager, Astrid G. Kruizinga, Marieke Pronk-Kleinjan: Majority of shrimp-allergic patients are allergic to mealworm . In: Journal of Allergy and Clinical Immunology . tape 137 , no. 4 , April 1, 2016, ISSN  0091-6749 , p. 1261–1263 , doi : 10.1016 / j.jaci.2016.01.005 , PMID 26944404 ( jacionline.org [accessed March 10, 2020]).
  20. ↑ What consumers need to know about insects as a snack. April 27, 2018, accessed March 10, 2020 .
  21. ↑ Massimo Marangi, Barbara Zechini, Angelica Fileti, Giorgio Quaranta, Antonio Aceti (2003): Hymenolepis diminuta Infection in a Child Living in the Urban Area of ​​Rome, Italy. Journal of clinical Microbiology 41 (8): 3994-3995.
  22. ↑ Y. Yang, J. Yang et al .: Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 1. Chemical and Physical Characterization and Isotopic Tests. In: Environmental Science & Technology. Volume 49, Number 20, October 2015, pp. 12080-12086, doi : 10.1021 / acs.est.5b02661 , PMID 26390034 .
  23. ↑ Y. Yang, J. Yang et al .: Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 2. Role of Gut Microorganisms. In: Environmental Science & Technology. Volume 49, number 20, October 2015, pp. 12087-12093, doi : 10.1021 / acs.est.5b02663 , PMID 26390390 .
  24. ↑ Rob Jordan: Plastic-eating Worms May Offer Solution to Mounting Waste, Stanford Researchers Discover. In: Stanford News. Stanford, September 29, 2015, accessed January 12, 2019.
  25. ↑ SS Yang, AM Brandon et al .: Biodegradation of polystyrene wastes in yellow mealworms (larvae of Tenebrio molitor Linnaeus): Factors affecting biodegradation rates and the ability of polystyrene-fed larvae to complete their life cycle. In: Chemosphere. Volume 191, January 2018, pp. 979-989, doi : 10.1016 / j.chemosphere.2017.10.117 , PMID 29145143 .