For Bees, Tongue Size Matters: Insects Lap Nectar with Different Lengths

Did you know that bees have tongues? Now, scientists have taken a closer look at them to see what determines the length of their tongues, which could be crucial to understanding bee species' resiliency to change.

A compatible tongue length is essential for bees to pollinate flowers. In fact, some insects and plants are closely matched, with bee tongues sized to the flower depth. Other bee species, though, are generalists and instead flit from flower to flower, collecting pollen from a variety of plants. Yet understanding tongue lengths could help ecologists understand and predict the behavior of bee populations-something that's more important than ever as bee populations continue to decline.

Not surprisingly, though, bee tongues are hard to measure. There's a scarcity of reliable lingual datasets. That's why scientists looked for a more easily measured proxy-body size. Bee tongues are proportional to body size, but modulated by family adaptations. Using this information, the scientists created an equation to predict tongue length.

Bees lap sugar-rich nectar from within cupped flower petals. Long flowers like honeysuckle or columbine are too deep for short-tongued bees, though. By that same token, long tongues are harder to wrangle into short flowers. This means that long-tongued bees are often specialists and favor a few deep-throated flower species.

Because specialists depend on just a few flowers, they can be more vulnerable to change. In fact, tongue length can be intertwined with a species' risk of extinction, as well as specialization.

These latest findings, including the new equation, could help researchers assess bee species' risk of extinction or population decline. This could be extremely important in the future as insects adapt to climate change and other environmental shifts.

The findings will be presented at the 99^th Annual Meeting of the Ecological Society of America in Sacramento, Cal.