MEASURING COLONY SIZE WITH SCIENCE, PART 2
In my previous post, I introduced the concept of BPUs, or Bee Power Units, as I like to call them. The basic idea is to measure the heat emitted by a bee colony to calculate the number of bees inside. I also introduced the method of using infrared imaging to measure heat, which is what I’ll be diving into in this blog.
Much like how bees’ ability to see in ultraviolet allows them to see things not visible to us humans, the other side of the spectrum (literally) allows us to view things we couldn’t otherwise see through human eyes. In case my pun wasn’t obvious enough, I’m talking about infrared light.
BIO (OR, B-EYE-O) HACKING
For those of you who wish to one day see infrared light through your own eyes, there's hope! A laboratory at the University of Science and Technology in China has discovered a way for mammals to see in infrared. By injecting nano-particles into the eyes of mice, researchers enabled the mice to see in infrared. As cool as this sounds, I’m not quite ready to inject nano-particles into my eyes. You gotta walk before you can run. Fortunately, there exists technology that gives us humans the capability to see in Infrared with absolutely zero eyeball injections required. They call this technology "infrared cameras".
In case you haven't been following our recent activity, infrared imaging is kind of our thing. Specifically, our product Verifli analyzes infrared images of beehives in order to calculate the strength of the colony within.
SEEING THINGS IN A DIFFERENT LIGHT
So! Now that we've got the cool Sci-Fi stuff out of the way, let’s take a peek at some images:
Can you tell the difference? Probably! Hive B shows a little more red/orange than the other, which means there's more heat coming out of it. Naturally, since all animals (and objects in general) radiate infrared energy, the more of an animal/object you pack into a space, the more heat radiates to the space's surface area.
You've experienced this phenomenon firsthand if you've ever been in an over-crowded room that felt more and more stuffy as more people filed in. If you took an Infrared image from outside that room before and after it filled up with sweaty bodies, you'd see a difference in the temperature of the walls. Same thing happens inside a beehive: more bees, more surface heat. How about this next picture; which of the two hives do you think has more bees?
This one's a little tougher to tell. Hive C appears to be slightly warmer in the first honey super. But the heat in Hive D's brood boxes looks a little less "splotchy" than Hive C... So it's a wash then, right? Basically the same number of bees in each hive?
Wrong! There are roughly 7.5 more frames of bees in Hive C than there are in Hive D. That's a difference of over 10,000 bees. That's nearly 3 thousand extra foraging bees out pollinating your flowers.
SO WHAT?
So what's our takeaway here? Well, by simply glancing at these pictures, there's no way the human eye could possibly tell how many bees are within the hive. That's where we come in.
But you might say “Gleb! If we can't tell the difference, doesn’t that defeat the purpose of using heat as a metric for colony strength?” To that I say, “Nope.”
The method of measuring colony size via "frame counts" has been established by the UC Extension office for quite some time now. As I discussed in my previous post, this method entails peeking between two brood boxes and estimating how many frames are covered with bees. From both personal experience and from launching Verifli this February, we found that taking frame counts is not only tedious and arduous, it tends to be extremely unreliable.
Although human eyes are excellent at pattern recognition, most of us aren't like Rain Man. We can't instantaneously count thousands of individual items from a quick glance. And unlike toothpicks, bees aren't known to be cooperative and hold still while you count them one by one.
On top of that, time of day has a significant effect on the cluster size in a colony. If you take a frame count when it’s early morning and still a little chilly, the bees will be clustered tightly over fewer frames to retain heat. Later in the day, the cluster will loosen up and spread out across more frames as the weather gets warmer. But at that point in the day, thousands of foragers will have left the hive to collect nectar and pollen.
FINAL THOUGHTS
The physics are complex, but the algebra is simple: by measuring a hive's heat signature with infrared, we can calculate the number of bees inside. Notice that this equation removes the potential for human error.
Frankly, after 2 or 3 hundred frame counts, they all start to look the same. With Verifli, there's no ballpark estimates or fatigue after grading hundreds of hives in a day.