| Euglossini | |
|---|---|
 | |
| female Euglossa (carrying pollen) | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Apidae |
| Clade: | Corbiculata |
| Tribe: | Euglossini Latreille, 1802 |
| Genera | |
| Diversity | |
| c. 200 species | |
The tribe Euglossini, in the subfamily Apinae, commonly known as orchid bees or euglossine bees, are the only group of corbiculate bees whose non-parasitic members do not all possess eusocial behavior.
Most of the tribe's species are solitary, though a few are communal, or exhibit simple forms of eusociality. [1] There are about 200 described species, distributed in five genera: Euglossa , Eulaema , Eufriesea , Exaerete and the monotypic Aglae . All exclusively occur in South or Central America (though one species, Euglossa dilemma , has become established in the United States). The genera Exaerete and Aglae are kleptoparasites in the nests of other orchid bees. All except Eulaema are characterized by brilliant metallic coloration, primarily green, gold, and blue.
Females gather pollen and nectar as food from a variety of plants, and resins, mud and other materials for nest building. Some of the same food plants are also used by the males, which leave the nest upon hatching and do not return. [2]
Male orchid bees have uniquely modified legs which are used to collect and store different volatile compounds (often esters) throughout their lives, primarily from orchids in the subtribes Stanhopeinae and Catasetinae, where all species are exclusively pollinated by euglossine males. These orchids do not produce nectar, and hide the pollen on a single anther under an anther cap; orchids are not visited by females, as females require both nectar and pollen as food provisions for their offspring, and visit other types of plants to obtain these resources. The whole pollinarium becomes attached to the male as it leaves the flower. Several flowers from other plant families are also visited by the bees: Spathiphyllum and Anthurium (Araceae), Drymonia and Gloxinia (Gesneriaceae), Cyphomandra (Solanaceae), and Dalechampia (Euphorbiaceae) contain one or more species that attract male euglossines. [2]
The chemicals are picked up using special brushes on the forelegs, transferred from there by rubbing the brushes against combs on the middle legs, and finally these combs are pressed into grooves on the dorsal edge of the hind legs, squeezing the chemicals past the waxy hairs which block the opening of the groove, and into a sponge-like cavity inside the hind tibia. [3]
The accumulated "fragrances" are evidently released by the males at their display sites in the forest understory, where matings are known to take place. [4] [5] The accumulated volatiles were long believed to be used by males as a pheromone to attract females; however, female attraction to male odors or to orchid fragrances has never been demonstrated in behavioral experiments. Instead, it is now thought that the function of the male odors is to signal male 'genetic quality' to females, [6] [7] because great effort must be expended by males to collect orchid fragrances and thus only the most fit males could gather complex odor mixes. This would constitute an unusual example of Zahavi's handicap principle, analogous to the male peacock's tail. [8] The relationship between male euglossine bees and volatile chemicals is essentially unique in the animal kingdom.
Scientists use single synthetic compounds as bait to attract and collect males for study; among them are many familiar flavorings and odors considered appealing to humans (e.g., methyl salicylate, eugenol, cineole, benzyl acetate, methyl benzoate, methyl cinnamate), and others which are not (e.g., skatole). [9]
It is also important to note that resource 'hot spots' wax and wane throughout the year as plants bloom and die, largely due to temporal changes, particularly between the changing of seasons. This often shifts euglossine bee preferences for certain chemicals over others. For Euglossa imperialis , studies have shown that there is a significant trend in chemical preference for cineole during later times in the year as opposed to methyl salicylate. In the local fragrance environment, a shift in the wind direction is another factor which may also cause another fragrance 'hot spot' to be included in the odor plume for euglossine bees. [10]
Neotropical orchids themselves often exhibit elaborate adaptations involving highly specific placement of pollen packets (pollinia) on the bodies of the male orchid bees; the specificity of their placement ensures that cross-pollination only occurs between orchids of the same species. Different orchid bee males are attracted to different chemicals, so there is also some specificity regarding which orchid bees visit which types of orchid. The early description of this pollination system was by Charles Darwin, though at the time, he believed the bees were females. [11] Not all orchids utilize euglossines as pollen vectors, of course; among the other types of insects exploited are other types of bees, wasps, flies, ants, and moths.
The male of Eufriesea purpurata is highly unusual among insects in seeking out and collecting large quantities of insecticide. Dressler (1967) discovered E. purpurata collecting aldrin [12] and Roberts (1982) observed them collecting DDT [13] [14] [12] in huge amounts from houses in Brazil, amounting to several percent of the bee's weight, without suffering any harm from the activity. [12] [13] [14]
Stanhopea is a genus of the orchid family (Orchidaceae) from Central and South America. The abbreviation used in horticultural trade is Stan. The genus is named for the 4th Earl of Stanhope (1781-1855), president of the Medico-Botanical Society of London (1829-1837). It comprises 55 species and 5 natural hybrids. These epiphytic, but occasionally terrestrial orchids can be found in damp forests from Mexico to Trinidad to NW Argentina. Their ovate pseudobulbs carry from the top one long, plicate, elliptic leaf.
Eucalyptol is a monoterpenoid colorless liquid, and a bicyclic ether. It has a fresh camphor-like odor and a spicy, cooling taste. It is insoluble in water, but miscible with organic solvents. Eucalyptol makes up about 70–90% of eucalyptus oil. Eucalyptol forms crystalline adducts with hydrohalic acids, o-cresol, resorcinol, and phosphoric acid. Formation of these adducts is useful for purification.
Methyl benzoate is an organic compound. It is an ester with the chemical formula C6H5CO2CH3. It is a colorless liquid that is poorly soluble in water, but miscible with organic solvents. Methyl benzoate has a pleasant smell, strongly reminiscent of the fruit of the feijoa tree, and it is used in perfumery. It also finds use as a solvent and as a pesticide used to attract insects such as orchid bees.
Vanilla planifolia is a species of vanilla orchid native to Mexico, Central America, Colombia, and Brazil. It is one of the primary sources for vanilla flavouring, due to its high vanillin content. Common names include flat-leaved vanilla, and West Indian vanilla. Often, it is simply referred to as "the vanilla". It was first scientifically named in 1808. With the species' population in decline and its habitats being converted to other purposes, the IUCN has assessed Vanilla planifolia as Endangered.
Eufriesea is a genus of euglossine bees. Like all orchid bees, they are restricted to the Neotropics.
Euglossa is a genus of orchid bees (Euglossini). Like all their close relatives, they are native to the Neotropics; an introduced population exists in Florida. They are typically bright metallic blue, green, coppery, or golden.
Eulaema is a genus of large-bodied euglossine bees that occur primarily in the Neotropics. They are robust brown or black bees, hairy or velvety, and often striped with yellow or orange, typically resembling bumblebees. They lack metallic coloration as occurs in the related genus Eufriesea.
Exaerete is a genus of euglossine bees found from Mexico to northern Argentina. Like all orchid bees, they are restricted to the Neotropics. All but one species is metallic green, and they are cleptoparasites in the nests of other euglossines in the genera Eufriesea and Eulaema. It contains the following species:
Aglae is a genus of euglossine bees, with the only described species Aglae caerulea. Like all orchid bees, it is restricted to the Neotropics. They are metallic blue. This species, like the genus Exaerete, is a nest parasite on free-living Euglossini. A. caerulea lays its eggs in the nests of Eulaema nigrita, and possibly other Eulaema species.
Euglossa hyacinthina, is a species of the orchid bee tribe Euglossini in the family Apidae. With a tongue that can get up to as long as 4 cm, this orchid bee species is found in Central America. Living in a neotropical climate, E.hyacinthina has adapted to hot and humid weather. The bee has darkly shaded, translucent wings and a metallic, glossy blue skeleton.
Euglossa dilemma, the green orchid bee or dilemma orchid bee, is a species of solitary euglossine bee native to a broad area of Central America, and recently introduced to Florida in the United States. It was first detected in Broward County, Florida in 2003, and initially identified as Euglossa viridissima, but further study revealed that E. viridissima as previously defined consisted of two cryptic species, and the one present in Florida was new to science.
Eulaema meriana is a large-bodied bee species in the tribe Euglossini, otherwise known as the orchid bees. The species is a solitary bee and is native to tropical Central and South America. The male collects fragrances from orchid flowers, which it stores in hollows in its hind legs. Orchids can be deceptive by mimicking the form of a female and her sex pheromone, thus luring male bees or wasps. Pollination will take place as the males attempt to mate with the labellum, or the tip petal of the flower. Male E. meriana are territorial and have a particular perch on a tree trunk where it displays to attract a female. After mating, the female builds a nest with urn-shaped cells made with mud, feces, and plant resin, and provisions these with nectar and pollen before laying an egg in each. These bees also have complex foraging and wing buzzing behaviors and are part of a mimicry complex.
Pollination traps or trap-flowers are plant flower structures that aid the trapping of insects, mainly flies, so as to enhance their effectiveness in pollination. The structures of pollination traps can include deep tubular corollas with downward pointing hairs, slippery surfaces, adhesive liquid, attractants, flower closing and other mechanisms.
Exaerete smaragdina is a species of kleptoparasitic euglossine bees.
Euglossa cordata is a primitively eusocial orchid bee of the American tropics. The species is known for its green body color and ability to fly distances of over 50 km. Males mostly disperse and leave their home nests, while females have been observed to possess philopatric behavior. Because of this, sightings are rare and little is known about the species. However, it has been observed that adults who pollinate certain species of orchids will become intoxicated during the pollination.
Exaerete frontalis is a kleptoparasitic species of euglossine bees.
Eufriesea surinamensis belongs to the tribe of euglossine bees and as such is a species of orchid bee. This should not be mistaken with the species group surinamensis, which includes Ef. surinamensis among other Eufriesea species.
Euglossa imperialis is a bee species in the family Apidae. It is considered to be one of the most important pollinators to many Neotropical orchid species in mainland tropical America. It is also one of the most common non-parasitic euglossine species in lowland Panama. E. imperialis, unlike many other bee species, is not a social bee in the sense that there is no apparent morphological or physiological division within the species to distinguish individual bees to be part of a worker or reproductive caste.
Euglossa mixta is a species of orchid bee native to Central America and South America, it is a member of the genus Euglossa a group of brilliant green and blue bees specialized in pollinating certain species of orchids.
The pollination of orchids is a complex chapter in the biology of this family of plants that are distinguished by the complexity of their flowers and by intricate ecological interactions with their pollinator agents. It has captured the attention of numerous scientists over time, including Charles Darwin, father of the theory of evolution by natural selection. Darwin published in 1862 the first observations of the fundamental role of insects in orchid pollination, in his book The Fertilization of Orchids. Darwin stated that the varied stratagems orchids use to attract their pollinators transcend the imagination of any human being.
