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Mezcal Worm in a Bottle: DNA Testing Yields Unexpected Results

A study published in PeerJ Life & Environment analyzed the species of larvae found in bottles of Mezcal, a distilled alcoholic beverage made from agave. Somewhat unexpectedly, the study found that all the larvae were of a single moth species, C. redtenbacheri, which is one of the most commonly consumed edible insects in Mexico.

A new study published in PeerJ Life & Environment looked to identify the speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>species of larva found in bottles of Mezcal. Mezcal is a distilled alcoholic beverage made from any type of agave. It is often served with a slice of orange and a dusting of worm salt, which is a mixture of ground-up chili peppers, salt, and ground-up larvae of a moth species called Hypopta agavis.

Are people consuming larvae of the skipper butterfly Aegiale hesperiaris, or the larva of the moth Comadia redtenbacheri, the latter of which is thought to be declining in numbers in recent years? Or is the worm the larva of a weevil, or another unidentified insect species? Researchers used DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>DNA-based identification analysis of larvae inside 21 commercially available mezcals to determine their identity.

Mezcal is a type of distilled alcoholic beverage that is made from the agave plant, which is native to Mexico. It is similar to tequila but is made from a wider variety of agave plants and is typically produced using traditional methods such as underground pit ovens and stone mills.

Specimens were obtained from mezcal bottles that were purchased between 2018 and 2022.

  • All larvae appeared superficially very similar, with a distinct head capsule and prolegs that are characteristic of lepidopteran larvae.
  • Some specimens were white, others were pinkish-red.
  • Of the 21 larvae subjected to DNA extraction, 18 yielded DNA sequences that were suitable for analysis.

Maximum likelihood tree showing the placement of the 18 successfully sequenced mezcal worms (in bold and red) in relationship to publicly available COI sequences of Comadia redtenbacheri (Hammerschmidt) and related Cossidae species. Scale bar = number of substitutions/site. Credit: Photo by Jose I. Martinez

The results were somewhat unexpected. Historically there are about 63 species of larvae or “worms” that are consumed in Mexico, including the Tequila giant skipper (A. hesperiaris) which, given its name, implies that it is included in tequila and other mezcals.

The study found that all larvae are a single moth species affirming the importance of C. redtenbacheri for the mezcal industry. Larvae of C. redtenbacheri are one of the most popular edible insects in Mexico.

Closeup image showing a worm inside a bottle of “Lajita Reposado” mezcal. Credit: Photo by Akito Y. Kawahara

Adding larvae to Mexican beverages and foods (salts, garnishes, powders, etc.) is driven by health benefits and by beliefs that these larvae contain aphrodisiac properties (Contreras-Frias, 2013). This trend is resulting in greater demand that is applying pressure to local larval populations.

In response to the declining number of mezcal larvae, researchers have begun to develop methods to cultivate these larvae in captivity.

Reference: “Mezcal worm in a bottle: DNA evidence suggests a single moth species” 8 March 2023, PeerJ.
DOI: 10.7717/peerj.14948

Source: SciTechDaily