"Most pollinators visit several plant species over their lifetime, but often they will display what we call floral fidelity over shorter time periods," Brosi explains. "They'll tend to focus on one plant while it's in bloom, then a few weeks later move on to the next species in bloom. You might think of them as serial monogamists."
Floral fidelity clearly benefits plants, because a pollinator visit will only lead to plant reproduction when the pollinator is carrying pollen from the same plant species. "When bees are promiscuous, visiting plants of more than one species during a single foraging session, they are much less effective as pollinators," Briggs says.
The researchers conducted their experiments at the Rocky Mountain Biological Laboratory near Crested Butte, Colorado. Located at 9,500 feet, the facility's subalpine meadows are too high for honeybees, but they are buzzing during the summer months with bumblebees. The experiments focused on the interactions of the insects with larkspurs, dark-purple wildflowers that are visited by 10 of the of the 11 bumblebee species there.
The researchers studied a series of 20-meter square wildflower plots, evaluating each one in both a control state, left in its natural condition, and in a manipulated state, in which they used nets to remove the bumblebees of just one species.
The researchers then observed the bumblebee behavior in both the controlled plots and the manipulated plots. "We'd literally follow around the bumblebees as they foraged," Briggs says. "It's challenging because the bees can fly pretty fast."
Sometimes the researchers could only record between five and 10 movements, while in other cases they could follow the bees to 100 or more flowers.
"Running around after bumblebees in these beautiful wildflower meadows was one of the most fun parts of the research," Brosi says. Much of this "bee team" was made up of Emory undergraduate students,
|Contact: Beverly Clark|
Emory Health Sciences