Natures wonders: bumble bee learning (Introduction)

by David Turell , Saturday, July 01, 2017, 19:19 (2700 days ago) @ David Turell

How to get to the pollen in certain flowers?:

https://phys.org/news/2017-06-scrabble-foraging-bees.html

"Gathering sweet nectar from flowers, it turns out, is much more difficult than one might think, and it requires a lengthy learning process. By the time a bee has figured out how to efficiently pry open the lips of a snapdragon flower, for example, most likely it has made dozens, if not hundreds, of floral visits.

"How does a bee in charge of shopping for food needed to raise dozens of hungry larvae back in the hive learn to navigate the multitude of floral architectures it may encounter during an average workday, let alone over the course of its life?

"Mostly by what biologists call associative learning, more widely known as trial and error, researchers have found. But while extensive research—starting with famous bee researcher and Nobel laureate Karl von Frisch a century ago—has focused on uncovering how bees forage for nectar, much less is known about how bees go about collecting pollen, which constitutes the most important protein source for the developing brood in the hive.

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"Our findings suggest that unlike nectar foraging, which requires complex learning behavior, bumblebees already know how to collect pollen," says Russell, who did the research as a doctoral student in the UA's Graduate Interdisciplinary Program in Entomology and Insect Science, "and they do it by switching between two responses that are seemingly hardwired into their brains." (my bold)

"Once a bumblebee touches down on a flower, it wastes no time. If it senses that the anthers are laden with abundant pollen just waiting to be shaken off like ripened apples from a tree, the bee does the obvious: a behavior that bee researchers call "scrabbling." Using its mandibles and legs, the bee brushes the pollen grains onto its body, then combs them off into collection baskets located on each of its hind legs.

"'If you picture a happy toddler in a play pit filled with plastic balls, you get the idea of scrabbling," Russell says.

"However, some flowers make their pollen grains more difficult to access, or sport intricate anther designs that dispense only a little bit of pollen at a time

"That way, the plant makes sure pollinators don't eat it all, but carry it to other flowers for pollination instead, and also leave some for other visitors as well, so the flowers aren't limited to a single pollinator," he says.

"When visiting some of these trickier flowers, Russell's team found, bumblebees switch to a different behavior called sonication—or, in more familiar terms, buzzing. Not unlike a sonicating toothbrush that vibrates to shake plaque from teeth, a sonicating bee vibrates vigorously to free pollen grains hidden inside the flower.

"The team observed that the bees switched between these two motor regimes depending on chemical and mechanical cues: They scrabbled when pollen was abundant, and sonicated when pollen was scarce, either because the flower already had been depleted or because its pollen is less accessible by design.

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"Bumblebees tend to sonicate on pollen-concealing anthers right away, but they also buzz accessible anthers when they can't detect pollen by touch," Russell says. "We think they do that in an effort to collect the dregs from a flower after most of its pollen has been harvested."

"Being able to switch between two programmed routines allows bees to effectively collect pollen from flowers in many different shapes and forms, the researchers conclude. This flexibility also may explain a fact that had evolutionary biologists stumped for a long time: Flowers with concealed pollen stores evolved many times independently, suggesting that pollinators must always have had a way to harvest pollen from them, or else the co-evolution between the two would have led to a dead end and not survived.

"'Researchers used to think that floral sonication is a behavior only used to collect pollen from concealed pollen stores," Russell says, "but because we often observe bees buzzing on flowers with accessible pollen, we conclude that it's a behavior that has evolved as a general strategy to collect pollen from any type of flower.'"

Comment: The authors think this is an evolved instinct. Even bee brains have plasticity and can rewire. Fits common descent.