Cheshire

Awhile ago, I wrote a post about honeybee attack pheromones. It’s a strange coincidence that the chemical that makes things taste like bananas cues bees into attack. Well, in this issue of Medical Entomology (which has some other cool articles that I might blag about), some scientists looked a chemical that keeps bees from attacking.

I’m interested in this article because I’m working a summer job as a beekeeper. My boss and I are complete opposites, both politically and when it comes to bees. I’m liberal, he’s kind of conservative (more so than me)…I get swarmed by bees whenever I walk by a colony and he can work without gloves. It’s an odd coincidence that they react differently to me than to him.

This finding, however, might not just have an effect on beekeepers. We’re in the midst of many biological invasions and one this might have an impact on is the Africanized Honeybee. The Africanized (Killer) Bees are exactly the same as the Apis mellifera I work with, except for one important difference: when they attack, they attack in numbers that are unimaginable whereas the European strain I work with attacks a few at a time.

This is the problem with the Africanized bees…they’re quite dangerous. The numbers they attack in can be harmful even to healthy humans…you don’t need to be allergic to be harmed by Africanized bees. If enough venom is injected into you, it’ll destroy your muscles and red blood cells and the resulting waste will destroy your kidneys. It’s different from an allergic reaction.

Needless to say, a repellent would be a good thing. It takes about 1,200 stings to kill a human (LD50~18-20 stings per kilogram of body weight). Some of the honeybee colonies I work with probably exceed 10,000 bees, and the African strains have been known to chase people a quarter mile. They also regularly nest near human habitations. Needless to say, a repellent could be a good thing.

Image courtesy of iromizu.com

Bees have defensive behaviors, they don’t just sting at the first sight of any large intruder. They’ll run into you first. There’s a technical term for the behavior, but I’ve always called it ‘headbutting’. A pissed off colony sounds exactly like a good rainstorm through a veil.

It makes sense for a bee to have a warning because when a honeybee stings you, it sacrifices it’s life. When it stings you, it leaves it’s stinger inside you and most of it’s innards. It doesn’t recover…it simply flies around the intruder’s face and later dies.

So these two things are how aggression are measured. To measure aggression in a beehive, you simply take an object (preferably dark colored) and use it to piss off a bee colony. You count how many times it’s headbutted, and how many stingers are embedded in it. Because a honeybee can only sting once, the number of stingers correlates to how many bees will attack you. Lots of headbutting and lots of stingers means a pissed off bee colony.

Which brings me to methyl athranilate, the chemical structure of which is pictured above.this chemical is found in grapes and gives wine grapes their grapey flavor. It’s also produced as an artificial flavor used to flavor powder drink mixes like Cool-Aid, Poweraide and Gatoraide. It’s also used as an insect and bird repellent.

So how did they figure this all out?

If you’re thinking the life of an entomologist is a glamourous one, let me disabuse you of that notion right now. The scientists in this experiment used colonies of Africanized honeybees to do this experiment. To protect themselves, beekeepers wear funny looking suits like this…

…which cover every inch of the body bees could possibly sting. To test the defensiveness, they installed a microphone near the front of the veil and recorded how many bees hit the face of the veil and had the person inside the beesuit count how many hits they heard. To count the number of stings, they used styrofoam balls wrapped in leather.

In the headbutt tests, the researchers sprayed one person with the flavoring agent and the other with water. In the sting tests, they used styrofoam balls wrapped in leather one of which was sprayed with a solution containing this flavoring agent and the other of which was sprayed with water. To piss the colonies off, they threw a rock at it and ran away…strangely enough, just like I used to do to hornets nests when I was a kid.

It turns out that when sprayed immediately after the bees start attacking, this flavoring agent reduces the number of ‘headbutts’ by more than 90%, and more importantly, the number of stings received by the ‘attacker’ by more than 80%.

Even cooler, the researchers tested how this chemical would effect paper wasp colonization. They found that the chemical was almost totally effective in preventing paper wasp colonization in deer stands.

Very cool. I’m going to be trying this next week.

Pankiw, Tanya (2009). Reducing Honey Bee Defensive Responses and Social Wasp Colonization With Methyl Anthranilate Journal of Medical Entomology