The Amazing Orchid Bees

Bees are some of the most common organisms recruited by flowers to achieve sexual reproduction. Even the least plant savvy among us can tell you that. Individual species of flowering plants go to great lengths to stand out among the background of countless other flowering plants to ensure that bees (and other pollinators) visit their own kind. Some plants get very specific in this way, only attracting a few or even a single pollinator species to do their bidding. Nowhere is this more apparent than in the orchids. There are some orchids that have taken this specificity to the next level. Orchids in the subtribes Stanhopeinae and Catasetinae have turned the tables so that bees require their flowers for their own reproduction, a truly unique strategy for both plants and animals alike.

Decked out in metallic greens, blues, and reds, male Euglossine or orchid bees are a site for sore eyes. However, their behavior may be even more amazing. Before mating, male bees seek out special volatile compounds that they store in special pouches on their back legs. Just as teenage boys utilize various colognes, the male bees are using these scents to attract females. These compounds are not produced by the bees. Instead, they obtain them from the flowers of various species of orchid. Some of the most commonly encountered orchids that offer this service are those belonging to genera such as Stanhopea, Gongora, and Catasetum.

The male bees go to great lengths to track these flowers down. A single blooming orchid can come alive with the buzz of male bees vying for access to the scented compounds. They land on the flowers and begin scraping at the petals with special hairs on their legs. In the process, pollen sacs called "pollinia" get stuck to the backs of the bees. The next time a bee visits a flower it will brush some of the pollen off and reproduction for the orchid is achieved.

Specific species of bee require specific scents to attract females. Because of this, each orchid species often caters to only one species of bee, thus guaranteeing that those bees will only visit orchids of that species. In this way, precious pollen is not wasted. What's more, the influence these orchids have goes far beyond just helping male bees get laid. Euglossine bees are important pollinators throughout the rain forests that they live. Species like the Brazil nut tree (Bertholletia excelsa) rely on large bees such as Euglossines for pollination and will not produce seeds without them.

Photo Credit: Billtacular (http://bit.ly/1LuTn2Q), USGS Bee Inventory and Monitoring Lab (http://bit.ly/1AFD4G0), Ian Morton (http://bit.ly/1924m1R), barloventomagico (http://bit.ly/1xeYPAM), Quimbaya (http://bit.ly/1GXLr3D)

Further Reading:
http://books.google.com/books…

http://link.springer.com/article/10.1023%2FA%3A1021932131526