Wednesday, July 01, 2015

Radio in the Hive

Transmitters get smaller and smaller. The smallest transmitters today are measured in atoms and whole devices fit inside a pencil point. The problem has become the power source or the battery.You can attach radio tracking devices to all sorts of animals but only recently has it become possible to do so with insects. For that reason I was surprised to read that we were now tracking honeybees with radio telemetry.

Colony Collapse Disorder (CCD) is a serious problem killing off bees, the dutiful pollinators of virtually everything you eat. (or at least everything eaten by what you eat)  The idea was that radio tracking would allow scientists to learn about the movements of bees prior to collapse perhaps providing answers. Right now it's unclear if the problem is viruses, bacteria, fungus, mites, or pesticides or all of the above. By monitoring the bees’ flights, scientists could detect changes in bee behavior. More here. Dr. Martin Wikelski at the Max Planck Institute for Ornithology said “We could use that information to protect them.”

In 2009 Wikelski and his colleagues has succeeded in mounting a tiny transmitter to a bee. They had already succeeded with cicadas and dragonflies. They ran their first field tests in the village of Möggingen, Germany.  The radio transmitters looked like tiny silver backpacks with 3-inch antennas. The unit could be detected over a third of a mile away. That study found that Bumble bees flew up to 1.5 miles and explored areas over 100 acres. But there was a problem. A bumblebee weighs about 300 mg, the transmitter weighed 200 mg— A 66% increase. It's unclear what effect that would have on the bees behavior. I know it would slow me down. But honey bees are even lighter than bumble bees. they weigh in at roughly a twelfth of a gram, or 120 mg.  Current radio trackers weight more than the bee rendering that same technique non-viable.  Wikelski estimates the technology is close, perhaps 5 years away.

In 2007 and 2008, an team of scientists in Australia tried to instead track bees with tiny RFIDs. A RFID transponder has no battery and can therefore weigh substantially less. They glued the lightweight tags onto bees and mounted a scanner at the hive entrance. The data shows how many trips a bee made each day, for how long and when... but not how far or where. The goal today is to develop a radio tracking device that weighs about 20% as much as the bee 24 mg, the same as the RFID.