Sex, Bugs, and Rock & Roll I
Sex, drugs, and rock and roll are the three sure signs of a wild party. Well, they are when we're looking at a human party, but what if I want to throw an insect party? I know that for many of us it feels as though the summer has just begun, but the next thing we know it will be Labour Day weekend and backyards will be filled with final barbecues and bonfires. So over the next couple months, I'd like to give some tips on planning your big summer blowout bug-style, covering all three bases: sex, drugs, and rock n' roll.
You may be asking yourself "Do insects even care about any of these things?" Well... good question. We can't exactly get the bugs to fill out surveys for us or just ask them about what their idea of a good party is like we would with humans. The trick, it seems (as always), is in the scientific method.
Let's start with music choice. A good playlist can take weeks to develop. What are insects into nowadays? The Chili Peppers? AC/DC? Kanye? Beiber?? There have been rumours going around since the early 2000s that termites prefer rock music, but is this fact or propaganda set out by big rock and roll record labels? So many questions, so few answers. Luckily, a seemingly unrelated article about termite boring depth and vibrational frequency released by CSIRO a few years ago gives us some insight into how to make our party an absolute banger.
A termite in a different study from CSIRO. Thank goodness they're blind - that is a face that only a mother could love.
Dr. Theodore Evans and his team found that termites are actually very picky eaters and are particularly concerned with the size of their food. Similar to some people preferring to eat cake over cupcakes (or vice versa if you're really weird), some termite species prefer huge logs over small branches. You'd think that this would be an easy distinction for termites to make: in some cases this would be like the difference between a house and the Grand Canyon. But, as it turns out, termite workers are blind. Since their eyes aren't really an option, these guys have instead developed a technique to distinguish between big and small pieces of wood involving their legs. And no, I don't mean walking around a log and counting the steps it takes to get back to where you started, though that could be a good diet strategy. Instead, they use something called vibroacoustic signalling.
Vibroacoustic signalling - Communication through vibrations and sounds
When a termite chews on wood, the scraping of its mandibles creates vibrations that spread throughout the material and can be picked up by special structures in the termite's legs and antennae. The density and size of the piece of wood determine the frequency of these vibrations. This signalling serves two functions:
The termite doing the chewing can tell how big the piece of wood is
Other nearby termites will be able to hear their friend chowing down and may come to join them
This might sound kid of gross if you make a human comparison - who wants to hear themselves chewing? Or overhear the person at the next table over chewing? - but it works.
The next question is "What does this have to do with rock and roll?" Another good one. As you might already know, the sounds we humans hear are also created by vibrations, just air-vibrations instead of wood-vibrations. And instead of hearing with our legs, we use our ears. Since, for termites, vibrational frequency can provide some idea of how big (and how tasty) a piece of wood is, they prefer certain frequencies over others. So maybe they prefer certain frequencies of music over others as well! In Evans' study, the team found that Cryptotermes domesticus workers preferred a small piece of wood that generally produced a 7200 Hz vibroacoustic signal while being chewed on over a larger piece of wood that generated a 2800 kHz signal. To translate this to something our Party Planning Committee can use, we can compare the average fundamental frequencies in some songs. And, just to test the old rumours about termites and rock music, we'll see if genre has to do with anything:
Yes, my music choices were likely biased - this is the result of Googling "popular ___ songs" and trying to figure out how Audacity works.
As we can see, there's quite a bit of variation within each genre. Nonetheless, we see a general trend: rock music generally has quite low frequencies, rap music has quite high frequencies, and pop is somewhere inbetween. I was fully expecting pop music to be the highest (maybe due to recalling the high, peppy voices of Taylor Swift and Justin Bieber), so this is interesting in and of itself. But what do the termites think? None of the music frequencies we found came close to what the termites in Dr. Evan's study were listening for, which were up in the kilohertz, but if the trend he found (that termites preferred the higher frequencies when given two options) can be extended all the way down to the range of frequencies we're looking at, then Cryptotermes domesticus probably actually prefer rap! Now all those Spotify adverts informing me that Drake is dropping a new album will be worth it.
So while listening to rock music might not actually cause termites to chew through wood twice as fast, playing rap music on or close to wood could certainly make termites think it's tastier. The flip side of this is that throwing a baller party might also mean ending up with a severe termite infestation. And no house.
This is a dangerous game, as the signal that means "I now relate to the rat in Ratatouille, that's how good this food is" to one insect might mean "I knew we should've just ordered Chinese food" to another. Vibroacoustic signalling can be used not just for information about food, but can also be used to convey information about, for example, potential dangers to a colony. Drs Hunt and Richard have reviewed the vibroacoustic signals of social insects (and obviously if we're throwing a party we want to focus on the more social insects) and found that there is a very wide range of uses for vibroacoustic signalling:
Macrotermes subhyalinus - alarm calls due to "jerking" behaviour
Polistinae polistes - use lateral shaking motions to indicate that they're leaving the nest; antennal drumming of nest cells may cause caste differentiation (for the worse)
Epiponini - parasite alarm and potential nest abandonment
Honey bees - the tremble dance (like the waggle dance, but with no directional component) causes less bees to leave the hive and more to start processing nectar
Ants - intruder alert
Even within termite species, it is hypothesized that different species prefer different sizes of wood (and different frequencies) so that they don't have to compete with each other for that food. If you like cake and I like cupcakes, we don't have to elbow each other at the dessert table in order to get the best pieces since we're both going after different things.
So please, while vibroacoustic signalling means that rap may be a good go-to if you like Cryptotermes domesticus, check not only the "order" column, but also the "species" column of your RSVP list before making your playlist.
Check back on August 1st for more tips on hosting the biggest, buggiest end-of-summer bash of all time.
Evans, T. A., Lai, J. C., Toledano, E., McDowall, L., Rakotonarivo, S., & Lenz, M. (2005). Termites assess wood size by using vibration signals. Proceedings of the National Academy of Sciences, 1 02(10), 3732-3737.
Hunt, J. H., & Richard, F. J. (2013). Intracolony vibroacoustic communication in social insects. Insectes sociaux, 60(4), 403-417.