Today I bring you one of my favorite parasitoids, the Jewel Wasp. This gorgeous little wasp, also known as the Emerald cockroach wasp has a fun little reproductive method which involves using cockroaches as a host for their larvae. Yesterdays video was of a fly parasitoid that uses caterpillars as a host for its many young; this wasp is a little different. It will sting into a specific ganglia (nerve bundle) in the thoracic segment (where the legs and wings originate). This first sting renders the cockroach unable to move under its own power; the second sting turns it into a zombie which is then drug around and manipulated by the wasp.
I was just referred to an interesting post on the absolutely amazing blog Why Evolution is True (seriously, check them out). The post is a somewhat old one regarding possible mimicry in a moth species found in Malaysia and Borneo. According to the post, some entomologists look at this and see….well, you look first, think about what you see and then highlight my “…” text below the image.
“…The researchers debated back and forth and have determined they believe those are two flies flying towards bird droppings…”
Bird dropping moths are not a new idea (just Google it, you’ll find a number of species) but this idea that it is two flies on the forewings going towards the droppings is a new one on many. What’s also interesting about this case is that the researchers associate an odor with the moth. Stinky moth!
It’s a very interesting idea and one that shouldn’t be dismissed right off hand. It also shouldn’t be accepted right off hand. A few of us who first looked at the image saw beetles, not flies. And what evolutionary occurrences would have take place in order for such an adaptation to arise? We don’t know. I encourage you all to check out the post and subscribe to their blog too. It’s a hoot. See below for my comment on their post.
There are hundreds of chemical compounds/scents emitted by a decomposing human (or other species) corpse. Not every odor attracts a fly and not every species is attracted/repelled by such odors. If we go with the hypothesis that this is an adaptive mechanism that results in fooling potential predators, such predators could:
A) smell it and think it’s rotten,
B) see it is something which is attractive to flies and therefore not of food-value
Eyespots are normally on the outer portions of wings and serve to distract predators from the main dish (their body) and instead result in getting nibbled on the wing tips which can result in higher survival rates for the butterfly.
I personally don’t see flies and I have to *really* look to “see” flies. I see beetles more immediately, as others have mentioned. Just going by general size and shape. And just because you can’t think of a beetle species with a red head just remember…400,000 species of beetles.
All too often we entomologists (and my fellow wannabees) want really-super-duper-hard to find something and then we eventually see it. I’m not saying that’s what this is; but confirmation bias is something we all need to be wary of. Does it look like a type of mimicry? Yeah, sure. Especially with the odor association. But as all of my fellow graduate students like to say when we end our presentations: More research is required.
Yes the bees!!! Bees are amazing little creatures. They do so much for the ecology of the planet. When I first typed that I wrote “…our planet” but then thought better of it. The majority of life on this planet is invertebrate. Ten percent of the terrestrial biomass is termites & ants. There are over 400,000 species of beetles identified to date and more on the way I’m sure. But when someone mentions they study insects bees are one of the first that will come to mind. Often people will think of butterflies first but I’ve found that many people seem to store the knowledge that butterflies are insects in a separate part of their brain. Sort of as if they think something that pretty couldn’t possibly be an insect. To which I say, “There are THOUSANDS of ‘pretty’ insects that are not butterflies!”
But back to the bees. In my studies (i.e. watching tv while avoiding actual work) I heard a nifty tidbit of information about Honey Bees. Yes, we all know about their decline and all of that (and “all of that” is a big can of worms I’ll avoid for now) but there are people who are actually using bees to sniff out bombs and other contraband at airports! How cool is that!?! The principles are essentially the same as those we all remember from Dr. Pavlov and his dogs. The classic Pavlovian response of the dogs when, after a period of training, the dogs were conditioned to salivate to the sound of a bell because it had become associated with food (ring bell, dog gets food).
Bees operate quite similarly to the dogs and us for that matter. By placing the bee in a small container, adding the odor you want it to detect in the box along with some sugar, repeat a few times and soon the bee has the same reaction to that odor as Pavlov’s dogs had to that bell. They seek out the smell because they associate it with sugar! A British company (Inscentinel) has conditioned bees to signal not only for explosive residues in suitcases and other luggage, but also in minefields. According to them they are ‘cheaper to keep and quicker to train then dogs.’
This idea was inspired by the work of Dr. Bitterman in Hawaii back in the 1980’s. Their research showed at the honey bee would extend their proboscis when their highly sensitive antennae were touched with sugar water. Some flies have a similar reaction to certain “flavors” coming into contact with their feet (yup, they taste with their feet!) Dr Bitterman and Co. took this a step further, much like Pavlov and wanted to see if you could associate the an item, in their case peppermint, with the sugar to elicit the same response. By pairing the peppermint scent with sugar, followed eventually by just the peppermint scent, the bees learned that peppermint was a source of sugar. And yes, I used the word learned. These same researchers have recently shown that honey bees are capable of actual learning and have demonstrated as such in a variety of experiments.
So there you have it. A few more ways how insects are totally amazing. And now a little about Pavlov’s less well known experiments on cats courtesy of the incomparable Eddie Izzard.
As I mentioned yesterday, we are going to spend a few days looking at the different ways insects communicate. Today we will venture into the world of auditory communication.
Crickets probably represent the most often thought of insect when it comes to insect sound production. If you have ever been out in a field on a warm summer evening you can’t hear a darn thing besides those little buggers going at it. And that’s the point of their sounds, is to “go at it.” The calling sound we hear is a mating call. Contrary to what many thing, the sound is not produced by the male cricket rubbing its two legs together, but rather by rubbing its wings together. While there are some insect species which rub the leg against the adjacent forewing (most forward originating wing) this is not true of crickets and katydids. Being science-type people, we have to give this activity a fancy name and we have dubbed it “Stridulation”…and it was good. Stridulation is simply the rubbing together of two specific body parts in order to produce a sound. These two parts are called the file and the scrapper. The scrapper has “teeth” on it and the file is smoother, though it may still have some bumps. The sound is produced similarly to how you might rub a pencil over a comb.
Cool as this may be (well, cool to us nerds) this does have its drawbacks. Not only do we hear those crickets singin’ away, but so do their predators. In some areas of the country there is a species of fly which is able to tune into that specific sound the cricket makes, find it and lay a larvae on it. The larvae then gets inside the cricket and starts to chomp down on the crickets innards, hanging out in its muscle tissue. The cricket is still alive while the larvae is in there, though it’s not going to have a good few days. The larvae depletes the crickets needed nutrients and even though the cricket is still eating, it is losing some of what it needs from that food to the parasite.
Not only does that cricket need to worry about predators and parasitoids finding it, it also needs to worry about how much energy it’s using. Yes, auditory communication has its perks; signals can be sent out quickly, it goes in a variety of directions and information is passed on with or without a direct line of sight to the intended target. If this was, for example, visual communication, the intended recipient would need to be right in the line of sight to see whatever display was being made, but not with auditory. However, there are some drawbacks. It’s horribly expensive and highly inefficient. A cricket can use around 1/2 of its energy stores in a given evening all with a measly 1% efficiency level. Yikes! Not only that, but this poor guy also has to contend with wind, rain, plants and other things that might distort or block the sound from getting where it needs to be. Being a cricket isn’t so easy, is it?
Given these potential problems, most insects have taken to using substrates (surfaces/substances) as a means to transmit the sounds they are producing. This typically takes the form of tapping on bark, leaves, stems, etc. This is especially effective when we’re talking about insects which live on the same plant and need to pass info around.
Once the insect makes its mating call, the auditory fun doesn’t stop there! Some insects need special sounds to be made before and even during mating in order for the sweet, sweet love to be made. Take this Noctuid moth for example. At the end of this video we hear an ultrasonic sound that the male makes while it’s attempting and then succeeding in mating with the female. If he doesn’t make that sound, she will leave. She’s a picky lady!
The ability to produce sound is believed to be a rather recent evolutionary adaptation that insects have developed. I say “recent” as in, compared to other methods that arose with the earliest arthropods 400 million years ago. Insects and their arthropod relatives have been on this planet a very long time and will continue to populate it long after the zombiepocalypse has doomed us all. And when that day arrives, somewhere there will be a cricket screaming its wings off trying to find a lady for the night.
So how would you fare during the Zombiepocalypse? I’ve got my boomstick at the ready.
For more info about what I touched on above check out the following links and resources:
I’d like to tell you a bit about insect communication but first we need to decide what exactly “communication” is. This might sound like an easy task but it’s not. Experts in the field do not even agree on an exact definition of “communication” when it comes to insects. Or heck, even communication between each other! First, let’s think about how we communicate; by text right? That could be a form of visual communication. You poke away at the phone, some sort of gibberish appears and you send it on the lines to your friend who then sees it and deciphers your pecking to decide what you were writing. You feel your phone vibrate when that text comes in. Tactile communication.
Now try to think way back to when we actually had to look at each other and use our words. Tough, I know, but we did do this. If you’re able to speak, you vocalize something, I hear it and interpret that as some sort of information and there ya go. Auditory communication.
Those two are simple and easy to define. But what about information which isn’t so obvious to our minds? Insects, as well as humans to a degree, emit chemical odors which can be picked up by another individual and interpreted. Think about that guy at the gym who’s been wearing the same gym clothes all week. Come Friday, you’re going to be picking up some nasty chemical odors from him and you’ll be able to interpret just what he (hasn’t) been doing…laundry. I have a friend who thinks coating himself in Axe Body Spray makes up for this. I disagree. It doesn’t. It just makes me think he took a turn for the douche…
Much like my friend with the rancid perfume, insects have naturally occurring “scents” that they can produce, though they might not always be scents as we think of them.
That seem pretty simple and self explanatory too, right? Sight, sound, smell. Clear. Concise and basic, right? So why all the confusion about what is and is not communication? But wait, there’s more!
There are a number of other ways communication can occur that isn’t even meant to happen! Think back to the cell phones. If you were to look at my 10-year old Nokia, brick-phone, you’d probably pick up information about my personality & character. Old, cranky, and cheap. You probably wouldn’t be that far off. That’s some information that you picked up without either of us trying. How about one of those tech-savy people who needs to get the latest iPhone X-Gen the day it comes out. When you look at that brand new, shiny phone you pick up information about that persons personality too. Once again, information is passed between parties, with or without any intention being placed. This too, is communication and now we get into the sticky bits where the experts start to disagree. Intention.
A recent article described the emission of blue fluorescence, visible within the UV spectrum that insects can see (but not humans or some other animals) by insectivorous plants (ex: Venus fly trap, pitcher plant, etc). Crazy huh! These plants have a ring of blue that’s only visible within the UV range. The plants don’t intend for this to happen…they’re plants…they don’t do much thinking. But the insects see this light and are attracted to it. Some would consider this communication, others no. I am on the pro side of this debate…just getting my biases out of the way up front!
Over the next couple of days I’m going to break down how insects communicate and give some examples. But first, we need to be on the same page as to what we’re talking about. For our purposes, “communication” is basically: The transmission of information between two or more entities. That’s as bare bones as you can get pretty much; but I think it works.
A few terms to keep in mind:
A “Cue” is information sent out but picked up by something/one other than the “intended” receiver. Perhaps a cricket making a mating call which is heard by a predator that finds it based on the sound and eats it. Poor cricket…
A “Signal” is information sent out and picked up by the “intended” receiver. Cricket makes the mating call and a female hears it, comes along and they get down. Happy cricket!
So there ya go. A basic introduction to insect communication. Tomorrow, we’ll look a little more in depth at some of those. Or maybe something else. We’ll see.