Bees find a way to lick climate change

Rising temperatures have led some species of bumble bee to develop shorter tongues.

By JOHN L. KOMINICKI // Nicole Miller-Struttman, a researcher and professor at SUNY Old Westbury, has been creating a bit of a buzz lately with a study suggesting that the effects of climate change are causing the tongues of some bumble bees to shrink.

Honey lovers need not read on: Bumble bees gather just enough nectar for day-to-day survival and die off in the winter, leaving behind a a few fresh queens to jump-start new colonies in the spring. But if you’re into apiology — the Latin word for bee is apis — or just want to keep up with how warming temperatures are rocking the planet, stay with me.

struttman

Nicole Miller-Struttman

Miller-Struttman’s research covers two species of bumble bees in the Rocky Mountains whose tongues have shrunk nearly 25 percent over the last 40 or so years. Tongue size is important in bees because it controls which flowers they can work over for nectar. Some bumble bees have amazingly long tongues — the equivalent of a human tongue reaching to the waist! — while others have a more modest proboscis, as drinking straw-like bee tongues are called by apiologists.

Being blessed with a long tongue allows bees to harvest nectar from flowers with deep corollas, the tubes formed by the flower’s petals. This is a pretty good gig as nectar collecting goes: The long-tongued bee gets to feast on nectar from flowers that insects with shorter tongues can’t, so there’s less competition for dinner. And the bees tend to limit their visits to the same types of flowers, meaning there’s a much better chance that pollen will be transferred to the right species. So not bad for the flower, either.

Rising temperatures have led to a general decline in mountain flowers — by about 60 percent since the 1970s, Miller-Struttman’s team found — forcing long-tongued bees to feed on whatever is available, including varieties with shorter corollas. Over time, their tongues have evolved for the new mission, hence the less prodigious proboscis.

“When resources are low, it’s more advantageous to go to lots of different flowers because there’s more resources that way,” Miller-Struttmann said. “And it takes less energy to get to them because you don’t have to search them out as much.”

How does one measure bee tongues over 40+ years? Great question. The researchers studied bees in museum collections dating back to 1966 and documented a 24.4 percent decline in tongue length, or about 0.61 percent each year. As evolution goes, that’s warp speed.

There are still many questions needing answers. Will alpine flowers adapt to the bees’ new behavior by evolving shorter corollas? Is tongue evolution more widespread or isolated to the two species — of about 250 — studied by Miller-Struttman & Co.?

“It will be really interesting to use some models to see how sensitive some of these (flower) species we see are to changes in bumble bee behavior,” she said. “We documented something that has happened, but we’re not exactly sure what’s going to happen going forward. That’s true from both the plants’ and the bees’ perspective.”