Orchid bees - Essential to the ecology of New World tropical forests
21 March 2020 (2664 visits)Euglossine bees, better known as orchid bees or long-tongued bees, are found only in the Americas. More than 250 species of orchid bees have been identified, and new species are being discovered every year. They can be found throughout the tropical Americas, from Florida in the north, all the way down through Central and South America, as far as southeastern Peru and southern Brazil.
All the bee species belonging to the Euglossini taxon are large and colorful, ranging from bright green, gleaming bronze or gold, to a host of metallic blue tones, and even red and purple. In some species of orchid bee, these vivid colors can be found in startling combinations on an individual bee’s head, thorax and abdomen. But what makes orchid bees unique among all bee species is their extraordinarily slender and long tongue, which can be more than twice their total body length. In some species, these tongues can measure up to 4 centimeters (1.6 inches) in length.
Orchid bees are essential to the ecology of New World tropical forests. One of their principal roles is that of pollinators of more than 700 species of tropical orchids. A number of orchid species are pollinated exclusively by male euglossine bees, including many of the more than 3000 species of orchids found in Peru. In addition to pollinating the flowers they find in the understory of tropical forests, some orchid bee species will also venture into the rainforest canopy and beyond, where they pollinate certain species of emergent big trees. Orchid bees will fly up to 50 kilometers (30 miles) on a single trip when seeking out the particular flowers they are adapted to pollinate, an enormous distance for such a tiny insect.
Female orchid bees can be found in tropical forests gathering pollen and nectar for food, as well as collecting mud with which to build the small nests that house groups composed of daughters or sisters. They do not make or store honey, and they have no queen bee. Across most orchid bee species, only the males visit and pollinate orchids; however, these solitary males do not feed on orchids’ nectar or pollen. Instead, they employ special chambers on their hind legs to gather the fragrant scents produced by many orchids. Different orchid bee species are attracted to different scents, making them specialists in the pollination of specific species. At the same time, individual orchid species have developed unique adaptations, such as the positioning of pollen packets specifically designed to ensure pollination only by certain species of orchid bee.
Biologists have discovered that male orchid bees use these exotic fragrances to attract females and ensure they mate successfully, apparently by using odor signals to demonstrate their foraging abilities and the longevity that enabled them to visit a variety of species and gather a range of aromatic compounds. They release odors at special display sites in the forest understory where orchid bees gather to mate.
Several studies have been made of orchid bees in Peru’s Tambopata National Reserve. The chemicals that attract orchid bees to the flowers they pollinate are used by researchers, who simply put out the same compounds in order to gather the bees, which are then used in conservation-related experiments to determine what orchid bees need to thrive and ensure the continued health of the plant species they serve. Orchid bees are also important to the local economies of forest-dwelling human communities. In the forests surrounding the jungle town of Puerto Maldonado, in southeastern Peru, a handful of euglossine bee species are responsible for pollinating the flowers of the brazil nut tree. Without these specialist pollinators, there would be no brazil nuts to harvest.
