DNA Testing Yields Unexpected Results

Mezcal Bottle Worm

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A research revealed in PeerJ Life & Environment analyzed the species of larvae present in bottles of Mezcal, a distilled alcoholic beverage produced from agave. Somewhat unexpectedly, the research discovered that every one the larvae have been of a single moth species, C. redtenbacheri, which is likely one of the mostly consumed edible bugs in Mexico.

A brand new research revealed in PeerJ Life & Environment regarded to establish the 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 DNA-based identification analysis of larvae inside 21 commercially available mezcals to determine their identity.

Mezcal Bottle

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.
DNA Sequenced Mezcal Worms

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.

Mezcal Worm

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