Want his perfume? Steal one of his legs.

The art of mixing perfume has been practiced by humans for thousands of years, distilling essential oils and aromatic compounds to produce the desired scent. However, we are not the only species to indulge our sense of smell: male orchid bees (Euglossa bee) also collect scents from the environment, and each species mixes and creates its own unique "scent" to attract the hearts of females.

Orchid bee, Euglossa igniventris | Alejadro Santillana / Insects Unlocked

The insect perfumer

Orchid bees are a type of bee belonging to the subfamily Apoidea, mainly distributed in Central and South America. Most of them are brightly colored with a gorgeous metallic luster and use their long tongues to suck nectar from tubular flowers.

Orchid bees have long fascinated biologists because of the scent-collecting activities of male orchid bees and their intricate associations with the hundreds of plant species they pollinate. Male orchid bees are attracted to scents emitted by flowers and non-floral sources, such as fungi, resins, sap, and even rotten fruit and feces. They collect scent substances with their tarsal brushes and store them in specialized sac-like structures on their hind tibiae. Male orchid bees of all species have unique, specialized structures to collect and store natural chemical scents in their habitat.

Male orchid bees use "receptacles" on their thighs to store odorous substances and create "perfume" | USGS Bee Inventory and Monitoring Lab / Wikimedia Commons

About 650 orchid species are monopolinated by orchid bees; female bees are rarely seen in orchids, but they visit a variety of flowers for nectar and pollen.

The exact purpose of the "spices" collected by orchid bees has always puzzled scientists. Researchers have imagined that they are used as repellents, antibacterial agents, or to help orchid bees prolong their lifespan or increase vitality. Through observational studies, we believe that odor substances are very similar to human perfumes, and the "spices" collected by males will directly affect the choice of female mating partners. Recent evidence shows that these substances play a role in courtship, and female bees can use them to measure the quality of male bee genes.

An orchid bee visits a claw-lipped orchid, Gongora meneziana | Alex Popovkin / Wikimedia Commons

When a male orchid bee finds a scent source, it lands on its surface and secretes lipid secretions from its labial glands to dissolve the scent compounds. This process is similar to the enfleurage technique used by perfume makers to extract scents from plant materials. The drone then uses specific leg movements to transfer and store the oil-scent mixture into specialized "pockets" located on its enlarged hind leg tibia.

Male orchid bees spend most of their lives accumulating "perfumes", which include a wide variety of highly volatile aromatic compounds. During courtship displays, male bees release perfume, and female orchid bees use the chemical information contained in the male bees' perfume to judge the genetic quality of males. At the same time, different types of male bees produce different "fragrances", and female bees "recognize men by their scent" to avoid hybridization.

An orchid bee visits a bucket orchid, Coryanthes speciosa | Alex Popovkin / Wikimedia Commons

Which came first, the orchid or the bee?

Orchid bees that have collected the "perfume" need to beware of attacks from "robbers". Someone observed a male of an orchid bee, Eulaema nigrita, flying close to the ground around an insect leg. Upon closer inspection, it was discovered that it was the hind leg of a male of the same species! He attempted to obtain the "perfume" from it for his own use. On the same day, researchers observed more than one male bee obtaining the "perfume" from a torn-off leg. This brutal robbery behavior seems to be quite common among males of E. nigrita.

Marauding orchid bees. Orchid bees of the species Eulaema nigrita (sometimes classified as Apeulaema) fight over a scent substance, with one bee taking it from the other's fallen thigh | Fernando da Silva Carvalho Filho / Biota Neotrop

About 20 percent of the bee family (Apoidea) are social, meaning mothers and daughters live together, with queens and workers, and daughters cooperate to raise their sisters. Orchid bees, on the other hand, are mostly solitary nesters. But a female sometimes lives with her first daughters, even eating the eggs laid by her daughters and replacing them with her own. Male orchid bees usually leave the nest soon after emerging and never return.

Orchid bees and orchids have a close cooperative relationship. Flowers rely on bees for pollination to reproduce, and in return, bees receive compounds for making "perfume". However, male orchid bees do not rely on just one type of orchid. They can obtain fragrance from flowers of at least 10 different families of plants, as well as decayed wood, resin, fungi and other materials. From this, it can be inferred that the evolutionary trajectory of orchid bees may have strongly influenced the evolution of the orchids they visited, but the reverse may not necessarily be true.

Orchid bee, Euglossa championi | Alejadro Santillana / Insects Unlocked

In a study published in Science in 2011, biologists reconstructed the complex evolutionary history of plants and their pollinators, found out which orchid bees pollinated which orchid species, and analyzed the compounds collected by the bees. It turned out that orchids need bee visits more - orchids produce only about 10% of the compounds collected by bees. But orchids cannot reproduce sexually without bee pollination. The researchers speculate that the appearance of orchid bees predates orchids by at least 12 million years.

"Orchid bees evolved earlier and were very independent, and orchids seem to have been playing catch-up to the bees," said Santiago Ramirez, a postdoctoral fellow at UC Berkeley and the paper's lead author. As orchid bees developed a new taste for fragrance, orchids responded by producing new compounds to attract their pollinators.

Orchid bee, Euglossa mixta | Alejadro Santillana / Insects Unlocked

At a time when global biodiversity is in crisis, a decline in pollinating insects could have far-reaching consequences for plants. Many "specialized" orchids are completely dependent on the work of orchid bees and cannot attract other insects for pollination, so if one orchid bee becomes extinct, three or four species may go to the same fate. These insect perfumers play a vital role in the integrity and richness of the ecological environment.