May 27, 2010 | 2
Rare tropical orchids can be few and far between in the wild, often separated by spotty landscape and human-made obstacles. But powerful tropical orchid bees do the leg—or wing—work, flying great distances to pollinate isolated flowers and keep the flora gene pool fresh.
Just how far and where exactly these bees fly, however, has remained relatively obscure to researchers. Some studies had tracked bees by marking them and using bait flowers to lure them in for counting or by scouting out specific flowers that bees appeared to return to. But these results have created only a rough sketch of the range and routes of these bees.
A group of researchers now has acquired far more specific data, attaching tiny, 300-milligram radio transmitters to the backs of male orchid bees (Exaerete frontalis) to track their movements.
The bees clocked in at an average of 9.5 meters per minute, usually logging more than three hours of air time a flight. The longest flight recorded was nearly two kilometers, and one intrepid bee soared over the Panama Canal, eventually ending up some five kilometers away before returning days later closer to where it had been caught.
"The data confirm that male orchid bees habitually travel a distance that can help connect widely dispersed orchids or other plants which they alone pollinate, and that produce a few short-lived flowers daily," the researchers concluded in their study, published online May 26 in the journal PLoS ONE.
Burdening 612-milligram bees with radio transmitters might sound excessive, but the researchers maintained that the bees can "easily carry" them, Martin Wikelski, director of the Max Plank Institute for Ornithology, said in a prepared statement. And another member of the team, Roland Kays, curator of mammals at the New York State Museum, explained in a statement that "carrying the transmitter could reduce the distance that the bees travel, but even if the flight distances we recorded are the minimum distances these orchid bees can fly, they are impressive, long-distance movements." Of the 14 bees outfitted with transmitters, five were tracked through the full 10-day duration of the transmitter battery life, four were found dead and the others were lost.
"Radio tracking significantly improves our understanding of bees and the plants they pollinate," David Roubik, a senior scientist at the Smithsonian Tropical Research Institute, said in a prepared statement. "Now we can track orchid bees to get the distances and spatial patterns involved—vital details which have completely eluded researchers in the past."
"Given the escalating rate of human interference, and the potential for deterioration of pollination services, it is critical that we start to understand the complexities of these relationships," the authors noted in their paper. The new data from this study and others could help inform conservation studies as well as work in agriculture and general biology. At the very least, these results "help to explain how orchids these bees pollinate can be so rare," Kays said.
Image of bee with transmitter courtesy of Roland Kays et al., image of Exaerete frontalis courtesy of STRI
Video courtesy of Wikelski Lab