Blog contributed by Bettina Carter, Plant Protection Content Editor, CABI
Our honey bees are dying in large numbers, and in an attempt to understand why, scientists at the Natural Resources Institute and Rothamsted have developed an ingenious monitoring system using a technique called harmonic radar entomology. This involves attaching tiny antennae to the bees' backs to monitor their flight path. In this rather delicate operation each antenna is stuck to the bee's thorax by hand using a strong adhesive. A signal is emitted by a portable radar tracking system which is picked up by a diode in the centre of the antenna on the bee's back. This signal is unique and allows researchers to track the exact flying path of the bees. Each signal translates into a blip on a radar screen. A computer programme then transforms the series of blips into a flight path.
"This can be overlaid on maps of the area to accurately show where the insect has flown and the landscape features of that area," says Dr Jason Chapman, a radar entomologist at Rothamsted.
And what about the bees, isn't an antenna stuck to your back too much of a load to carry? Not at all, scientists say that bees have evolved over millions of years to carry heavy loads, including pollen masses almost half their body weight.
"The tag only weighs a tenth of their body weight and it is very easy for them to carry that weight," says Chapman. "Also, because they are used to carrying weight it doesn't affect their flight pattern in any way."
There is only one major drawback to the system and this is that only one bee can be tagged at a time which makes the research very time-consuming.
"Our longer-term plans are to develop the next generation of harmonic radars which will be able to track more than one bee at a time," says Chapman.
The technique of harmonic radar has been specifically developed for observing low-flying insects such as honey bees. There are other radar techniques for observing insects such as vertical looking radar (VLR) which are more suitable for long-term monitoring of high altitude insect abundance and movement.
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