Flight of the Bumblebee: A Soundscape for Survival

High up in the clover-laden alpine meadows of the Rocky Mountains, a group of scientists is listening to bumblebees. Their summer days amid Colorado's Ridge Long Term Ecological Research Site and at Pennsylvania Mountain might seem a mere idyllic on a clear summer day, but these scientists are doing research that may have profound implications for human society, and even for our survival.

Candace Galen from the University of Missouri, Columbia, lead author Nicole Miller-Struttmann from Webster University, and team of biologist are testing asking a unique question. Can we tell how effectively pollination is occurring by listening to the soundscape of bumblebees?

Consider these facts. The populations of bees worldwide are declining and with that decline over 85% of all the flowering plants in the world are affected. Our agricultural crops are suffering too. Over 75% of them are at the direct mercy of bees and the bees are declining. Over $200 billion dollars a year are lost because crops are not effectively pollinated.

Disease, parasites, pollution, fertilizers, pesticides, and changes in the world's climate are all affecting the bees we need to pollinate plants. Ecological changes can occur when major pollinators are reduced in numbers. Crops can fail. What do potatoes, okra, cashews, and watermelons have in common? They rely almost exclusively on pollination by bees.

Dr. Galen and her team are listening to the sounds of bumbles, specifically two native species, Bombax bleatus and B. sylvicola. They are listening in meadows dense with clover in flower. They are attempting, for the first time, to correlate the sound of bees with the efficacy of pollination.

The team discovered that both bee wing size and tongue length correspond with a characteristic buzzing frequency. They can listen to buzzing in the 120-400 Hz range and tell, at a non-species level, which sorts of bees are active. They listen using small receivers placed throughout the meadows that pick up the sounds of bees.

Why is this work important? Imagine this scenario. A watermelon farmer sits in her office and opens her computer. On it she sees a soundscape of her vast fields. Her field has been rigged up with a hundred small microphones. She can immediately see, graphically, where pollination is taking place -- and where it is not. She can also tell the general size and shape of the bees doing the pollinating. Software can alert her to changes in bee activity over the last 36 hours. Quickly she can locate trouble spots and act to make sure her watermelons will develop. It is a symphony that saves her crops.

Studies of populations of bats and birds have long been based on the data from sounds, the high squeak of a little brown bat or the call of a crow. Recording the soundscape of bees is new however. As the days in the Rocky Mountain summer moves on, scientists are learning how to track bees. Our world food supply might hang in the balance.