Mealworms are a popular pet food, but they are more than just pet food. These worms are larvae of the mealworm beetle, which goes by the scientific name Tenebrio Molitor and is a species of the darkling beetle.
Like all holometabolic bugs, mealworm beetles have four stages of life: larva, egg, pupa, and adult.
Mealworms typically measure about 2.5 cm or slightly more, whereas fully developed bugs are generally between 1.25 and 1.8 cm long.
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Tenebrionidae
- Genus: Tenebrio
- Species: T. Molitor
- Binomial name: Tenebrio monitor
The mealworm beetle mating and reproduction
For these Beatles, mating is a three-step process involving the male mealworm beetle chasing a female, mounting the female, and inserting his aedeagus to inject a sperm packet.
After the sperm packets are released, within a few days, the female mealworm Beatles burrows into soft soil to lay around 500 eggs.
The eggs take between four to 19 days to hatch, and they quickly become the target of many predators, including reptiles.
At the larval stage, mealworm is known to only feed on vegetation and dead insects. And they molt between each larval stage, or instar (9 to 20 instars). After the last molt, the larva becomes a pupa.
Once a pupa emerges, it appears whitish and turns brown over time. Depending on environmental conditions like temperature, after 3 to 30 days, it changes into an adult beetle.
Sex pheromones
A sex pheromone has been identified to be released by male mealworms. However, inbreeding reduces the attractiveness of the sex pheromones that are released by male mealworms.
The female mealworms are more attracted to outside breeders because their sex pheromones seem to smell stronger to the females. The unattractiveness of male signaling of inbreeds may be due to increased expression of homozygous deleterious recessive alleles that are caused by inbreeding.
Relationship with humans
Mealworms and Mealworm beetles are often used for studies and biological research. The relatively large size and ease of rearing and handling, coupled with its status as a non-model organism, are the qualities that make it useful in the proof of concept studies in biochemistry, basic biology, evolution, physiology, and immunology.
As pests
Mealworms are generally considered pests because their larvae eat stored grains. There is a possibility that mealworms originated in the Mediterranean region but later spread to many areas of the world due to human trade and colonization.
Hence their presence in almost every part of the world. The oldest archaeological records of this species can be traced to the Bronze Age, Turkey. There are also records from the British Isles and northern Europe from a later date.
However, mealworms are entirely absent from all archaeological findings from ancient Egypt.
As food
Mealworms are known as pet food, but they are edible for humans and are popularly consumed in practice called entomophagy.
There are historical records of the consumption of mealworms in many Asian countries, especially in Southeast Asia. Mealworms are commonly found sold in food markets and sold can be bought from street food sellers, alongside other edible insects.
Quite tasty and nutritious, baked or fried mealworms have been sold around the world as a healthy snack food in recent times, though the consumption of mealworms is not a recent development.
Mealworms can be reared easily on wheat bran, fresh oats, or grain, with carrots, sliced potato, or apple as a source of moisture. The little amount of space needed to raise mealworms is what has made them famous in many parts of Southeast Asia.
Mealworms have been introduced into the production of tequila-flavored novelty candies. However, mealworms are not served in tequila traditionally, and the “tequila worm” in some mezcals is mostly the larva of the moth Hypopta agavis.
Asides from food for humans, mealworms are typically used as food for pets such as captive reptiles, birds, and fish. They are also given to wild birds as food in bird feeders, especially during the nesting season.
Indeed, mealworms are considered useful because of their high protein content. Mealworms are also used as bait for fishing.
Mealworms are commercially available for bulk purchases and are usually available in containers with oatmeal or bran for food. Commercial mealworm growers include a juvenile hormone into feeding their mealworms to keep them permanently in the larval stage and get them to grow to an abnormal length of 2 cm or greater.
In waste disposal
In 2015, studies revealed that mealworms could quickly degrade polystyrene into the reusable organic matter at an unbelievable rate of about 34-39mg per day.
Also, there was no difference found between mealworms that were fed only styrofoam and those fed with conventional foods, during the one month, the experiment was carried out.
Microorganisms present inside the mealworm’s gut has been identified to be responsible for degrading the polystyrene, with a group of mealworms given the antibiotic gentamicin exhibiting no signs of degradation.
However, Isolated colonies of the microbes present in the mealworm’s gut, have proven to be less efficient at polystyrene degradation than the bacteria within their gut. At present no attempts have been made to commercialize this discovery.
