The Predator's Trap Was the "Scent of Love" – First Identification of "Airborne Sex Pheromones" in Nematodes

Overview

A joint international research team, including Professor Ryoji Shinya of Meiji University's Faculty of Agriculture and Professor Paul W. Sternberg of the California Institute of Technology, has discovered that male nematodes Caenorhabditis remanei*1 release "airborne sex pheromones"*2 that attract females.

The compound identified by the research team is methyl 3-methyl-2-butenoate (MMB)*4. Male C. remanei release MMB into the air, and females are strongly attracted to this scent. This research is the first to identify a volatile sex pheromone*3 in nematodes.

Surprisingly, MMB was already known as a compound released by the nematode-predatory fungus Arthrobotrys oligospora*5 to attract prey. In other words, the "scent of love" found for the first time in nematodes was also the "scent of a trap" used by predators to lure their prey.

Previously, MMB had been suggested as a potential chemical mimicry substance*6 that imitates nematode sex pheromones. This study clarifies that MMB is indeed a sex pheromone derived from male nematodes, strongly supporting the view that predatory fungi use this scent to deceive their prey.

This research was published on July 1, 2026, in the international academic journal "Communications Biology" from Nature Portfolio.

Background

Organisms exchange information about food, natural enemies, and mates using chemical substances such as scents and pheromones. Among these, sex pheromones are crucial signals for finding the opposite sex and have been extensively studied in insects for a long time.

Nematodes are small animals that inhabit diverse environments such as soil, water, plants, and animal bodies on Earth. Pheromone-based communication is known in nematodes, including the well-known model organism Caenorhabditis elegans. However, the sex pheromones primarily known in nematodes until now were compounds that diffuse through water or culture media. Whether nematodes, like insects, also search for mates using airborne scents, and their chemical identity, remained unknown.

On the other hand, the nematode-predatory fungus Arthrobotrys oligospora is known to release a scent that attracts nematodes. This fungus lures nematodes and nourishes itself by capturing them with specialized trapping organs. Previous research showed that a compound called MMB, released by this fungus, strongly attracts female and hermaphrodite*7 Caenorhabditis nematodes.

Therefore, MMB was thought to be a chemical mimicry substance imitating nematode sex pheromones. However, it was not known whether nematodes themselves use MMB as a sex pheromone.

Research Results

The research team then set out to identify the "airborne sex pheromone" released by male nematodes to attract females.

As a result, MMB was detected from male hermaphroditic nematodes C. remanei. In contrast, MMB was not detected from female C. remanei or male and hermaphrodite C. elegans. This indicated that MMB is a scent component specifically released by males, at least in C. remanei.

Furthermore, behavioral studies using synthesized MMB revealed that female C. remanei were strongly attracted to MMB. Conversely, male C. remanei were not attracted to MMB and tended to avoid it at certain concentrations.

These results clarified that MMB is a volatile sex pheromone released by male C. remanei to attract females.

Particularly significant is that the MMB identified in this study was the same scent substance used by the nematode-predatory fungus A. oligospora to attract prey. The "scent of love" found for the first time in nematodes was also the "scent of a trap" for predators to deceive their prey.

This research not only identified a volatile sex pheromone in nematodes for the first time but also demonstrated that predators utilize scents involved in the mating behavior of their prey. It is thought that in nature, a sophisticated "deception game" mediated by scents is being played out, unseen by us.

Future Prospects

This study has revealed that nematodes also possess intersexual communication using airborne sex pheromones. If the identification of pheromones progresses in plant-parasitic nematodes that damage crops and trees, it could lead to the development of new control methods utilizing artificial manipulation of nematode behavior, such as attraction, capture, or mating disruption.

Furthermore, by comparing scent substances released by nematodes and nematode-predatory fungi across various species, it is expected that the complex interspecies interactions mediated by chemical signals in nature will be elucidated. In particular, "chemical mimicry" and "deception games" where predators imitate prey sex pheromones to lure them offer a new perspective for understanding the invisible soil ecosystem.

Social Significance

In nature, organisms engage in complex information exchange using scents and chemical substances. This research suggests the possibility that sex pheromones used by nematodes to find mates are exploited as a "trap" by predators.

This indicates that chemical signals are not merely means of communication but can also serve as weapons to deceive others. Understanding interspecies interactions mediated by scent is crucial for elucidating the mechanisms of ecosystems.

Additionally, many nematodes are plant-parasitic and cause severe damage to crops and trees. Understanding the mechanisms of scents and pheromones that control nematode behavior could lead to the development of new control technologies in the future, such as attracting and capturing harmful nematodes or disrupting their behavior. From this perspective, the research team is currently searching for similar pheromone substances in parasitic nematodes.

Supplementary Explanations

*1 Nematode A multicellular animal belonging to the phylum Nematoda. Most are small, around 1 mm in body length, and inhabit diverse environments such as soil, water, plants, and animal bodies. They are considered one of the most abundant animal groups on Earth.

*2 Sex Pheromone A chemical substance that elicits reproductive behaviors, such as attraction and mating behavior, in individuals of the same species of the opposite sex.

*3 Volatile Sex Pheromone A sex pheromone that volatilizes into the air and is perceived as a scent by distant individuals. Unlike water-soluble pheromones, it acts via air, without relying on diffusion in culture media or water.

*4 MMB Abbreviation for methyl 3-methyl-2-butenoate. In this study, it was identified as a volatile sex pheromone released by male C. remanei that attracts females.

*5 Nematode-predatory fungus A general term for fungi that capture and feed on nematodes. Arthrobotrys oligospora is a representative nematode-predatory fungus that attracts nematodes, forms trapping organs, and preys on them.

*6 Chemical Mimicry A phenomenon where one organism produces or utilizes a substance that mimics the chemical signal of another organism, thereby manipulating the other's behavior. In this study, the possibility was shown that predatory fungi use nematode sex pheromones to attract prey.

*7 Hermaphrodite A reproductive mode in which an individual can produce both female and male gametes. In C. elegans, hermaphrodites typically reproduce through self-fertilization.

Publication Information

Journal: Communications Biology Paper Title: A male-derived volatile sex pheromone in Caenorhabditis nematodes identified through its mimicry by a predator Authors: Matthew R. Gronquist, Xuan Wan, Daniel Leighton, Yuki Togawa, Marika Sagawa, Paul W. Sternberg, Frank C. Schroeder, Ryoji Shinya DOI: https://doi.org/10.1038/s42003-026-10575-4

Research Funding

This research was supported by grants such as the Japan Science and Technology Agency (JST) "Emerging Research Grant" JPMJFR210A (Representative: Ryoji Shinya) and the Japan Society for the Promotion of Science (JSPS) "Grant-in-Aid for Early-Career Scientists" 17H07161 (Representative: Ryoji Shinya).