Curious nature: bumblebees don’t laugh around evolution

Bee-believe it or not, bees are considered the most important pollinator in the world. Lucky for us here in Colorado we have the fifth highest diversity of bees in the United States.

You can find 946 bee species native to Colorado. Native bees are important because they are the species that occur naturally in an area and form the basis of that ecosystem by pollinating native plants that could not reproduce as efficiently without them.

There are species of bees that have been accidentally brought to new places by humans, but the best known non-native bee, the European honey bee, is intentionally used for agriculture. Both native and non-native bees are important pollinators, but because native bees have co-evolved with the flowering plants in the region, they are better suited to pollinate these flowers. All of the bees we find here are extremely beneficial to the local ecosystem, but today we’re going to focus on a few bumblebees in particular.

Some very important native bees that we have in the Vail area are the bumblebees, bumbus sp. This name comes from the Greek word bombos, which means “a buzz”. Bumblebees are the most efficient pollinators of alpine ecosystems due to their ability to create their own heat and to fly long distances.

There are 24 different species of bumblebee in Colorado with unique pollination styles that are necessary for the reproduction of certain native plants, such as many plants in the legume (Fabaceae) and aster (Asteraceae) families. This special style of pollination is called buzz pollination. Bumblebees will land on a flower and then buzz their wings at a specific vibration that shakes the pollen from the flower’s anthers onto their body.

Not only are bumblebees necessary for buzz pollination, but some alpine bumblebees specialize in pollinating alpine tube flowers. Tubular flowers have fused petals that create a structure called a corolla, where bees go to eat pollen and nectar.

Two of these bumblebees, Bombus balteatus and B. sylvicola, have long tongues to reach the corolla of alpine flowers, such as the Indian brush and the alpine skypilot. These bees developed their long tongues through a co-evolutionary relationship with alpine flowers which have a tube-like structure.

These long-tongued bumblebees see changes as our climate changes. We have seen a 70% decrease in alpine flower density since 1970 due to drier conditions in the Alpine Living Zone. In 40 to 50 years, scientists have already discovered that the tongues of these bumblebees are shortening to become more generalized pollinators, an example of rapid evolution.

A recent study has shown that the length of these bumblebee tongues has already decreased by almost 25%.. The adaptation of a long tongue, which was once an evolutionary success, is being lost as bees need to generalize to access different flowers.

Bumblebees have been shown to already adapt to alpine climate change, but flowers may not survive the changes now that they are losing their specialized pollinators. This extraordinary case of rapid change shows us that climate change is already causing great changes in nature.

This fall, you may notice that you see bumblebees less often. Once the temperatures start to drop, most of the colony begins to die off. Only the queen bee will survive the winter and start her new colony in the spring. Queen bumblebees hibernate underground during winterunlike bees. You can help ensure their survival next year by planting native plants this fall and avoiding the use of pesticides and herbicides in your garden.

Liv Irelan is a naturalist at the Walking Mountains Science Center and a bee lover. You can find her trying to stalk bees on the local mountain biking and hiking trails around the valley.