The term “pheromone” was defined by the German biochemist Peter Karlson and Swiss entomologist Martin Lüscher in 1959. The word has two Greek roots: “pherein” (transport) and “hormone” (excite). Thus, pheromones were defined as substances secreted by individuals that received by other individuals of the same species, cause a specific reaction, behavior or biological change.
The first sex pheromone was discovered in 1959 by Adolf Butenandt (who won the Nobel Prize for Chemistry in 1930), after 20 years of work. From 500 000 females of silkworm (Bombyx mori), he received 6.4 mg of purified attractive sex pheromone: the bombykol (which is actually an alcohol). Adolf Butenandt was not the only one to question the role of these odors. For over 50 years, biologists have been interested in the role of odor emissions in animals and discovered that most living organisms produce substances they release into the environment. Wilson’s article in 1963 entitled “Pheromone “was a trigger for many biologists. Many scientists noticed that the topics they were studying could be reread in light of these new concepts. In 1960, Jeanine Barbier and Michel Pain isolated and identified the queen substance of bees, which inhibits the development of the ovaries of the workers. This was the first pheromone amending known to date.
Since then, progress in the field has been enormous. Numerous pheromones are now known in insects even though the early work of isolation and purification was slow at times. Few pheromones identified in aquatic organisms, however, were reported in brown algae in mold lakes and rivers. Some pheromones were discovered in fungi, one of them producing a sex pheromone: the female gamete secretes a substance that attracts the male gametes. This was the first isolated pheromone from a plant.
In vertebrates, the term pheromone is more elusive and there are many examples. Pheromones have also been identified in rodents, carnivores and monkeys. In these mammals, pheromones are generally secreted by glands near the sexual organs or the head.
Different types of pheromones
There are many kinds of pheromones and they can be divided into two major categories: incentive pheromones that affect the behavior of animals and modifying pheromones that act on the biology of animals.
Pheromones of territory are hormones that animals (e.g. canids) use to mark their territory. Trace pheromones have been identified as bile acid derivatives. The animals use them to trace their tracks (e.g. ants). The alarm pheromones are volatile (or very soluble in water for fish) and they are released by an animal in case of injury or attack by a predator, and that triggers the leak or aggression in other individuals of the same species. Sex pheromones indicate the availability of females to be fertilized. Depending on the type of reproductive cycle of the insect, pheromones play different roles. However, the coupling always takes place at a well-defined life cycle of the insect, and even at a specific time of day sometimes. Sex pheromones are by definition created to ease communication with each other in order to ensure the sustainability of the species.