Australian species really do have a way of doing things differently, and that extends down to insects. The blue-banded bee has been revealed as a headbanger, slamming into flowers a neck-threatening 350 times a second in an effort to collect pollen, rather than grasping the flower like other insects.
Like plants elsewhere, Australia's flowers have formed a symbiotic relationship with pollinating species, particularly bees. Some flowers are “buzz pollinated”, requiring larger insects to shake the flowers to release pollen, rather than picking it up directly like honeybees do with other flowers.
Bumblebees, the most famous buzz pollinators, grasp flowers in their mandibles and shake them around 240 times a second. It was generally assumed that other buzz pollinators used a similar technique. However, when an Australian and American team filmed Amegilla murrayensis, a species of Australian blue-banded bee that fills a bumblebee-type ecological niche they found something different. Sound recordings had already revealed that A. murrayensis uses a higher frequency, around 350 hertz, but what was more surprising was its shakedown method.
Instead of holding the flower, the bee bangs it with its head hard enough to release pollen trapped inside. Moreover, it seems that this is a more effective pollen removal method than the more common technique.
Superslow motion images of a blue-banded bee getting pollen from a flower. Headbanging starts at 20 seconds. Credit: Callin Switzer, Adelaide Botanic Gardens
“A. murrayensis spent less time on each flower,” the researchers reported in Arthropod-Plant Interactions. The more persistent bumblebee, used for comparison studies, is named Bombus impatiens. However, Adelaide University's Dr. Katja Hogendoorn, one of the paper's authors, told IFLScience the supposedly impatient bumblebees made multiple passes, known as buzzes, at each flower. Their Aussie equivalents got the job done with fewer buzzes of around the same length.
Despite this, bumblebees remain a threat to Australian native bees. Hogendoorn told IFLScience that bumblebees are able to start foraging at much cooler temperatures than Australian natives, and have become well established in Tasmania, displacing many native species in the process.
Growers of greenhouse tomatoes are keen to use bumblebees to pollinate their crops, something currently done using vibrating wands, but there are concerns that the introduction of bumblebees for this purpose will lead to their escape and establishment on the Australian mainland.
"Our earlier research has shown that blue-banded bees are effective pollinators of greenhouse tomatoes," Hogendoorn said in a statement. "This new finding suggests that blue-banded bees could also be very efficient pollinators – needing fewer bees per hectare [2.5 acres]."
Hogendoorn told IFLScience that the use of native bees would require greenhouse adaptations such as the use of glass, rather than plastic, as the plastic versions cut out the wavelengths of light the bees use to see. The main obstacle, however, is the lack of a breeding program capable of producing blue-banded bees in sufficient quantities, something Hogendoorn is working towards.
Buzz-pollinated flowers don't produce nectar, Hogendoorn explained to IFLScience, so need to offer an incentive to keep bees coming back. This is achieved by ensuring pollinators can't get all the pollen in a single visit, no matter how effective their shaking technique.
