NPR/NGS Radio Expeditions
13 Sep 1999
- 39.10917 -77.55778
Stereo=1; Decoded MS stereo
NPR/NGS Radio Expeditions
Show: Bug Communication
Log of DAT #: 3
ng = not good
g = good
vg = very good
04:39 Terry says time code
Clap [with camera: 4:44]
[Rolling in sync with TV]
*05:37 -AC: Oh, Wow, Ambi of hoppers.
Level check. We're sitting in an old farm yard near Leesburg, Virginia, listening to treehoppers. WOW + Ambi. 6:15 [plane]
7:31 RC: This is what I had in mind. I was thinking, we ought to go out in the field and record. Let's wire up a black locust tree, because that's what you get, these incredible signaling interactions. FX: wind AC: And that's wind we're hearing right now, rattling wind, which the insects hear all the time. RC: Yes. So they're on a plant that's shaking back and forth in the wind, it's noisy, and they're communicating in that kind of noisy environment, but then in these breaks in the wind, we hear a little flurry of signals.
AC: Have you ever heard them before like this?
RC: Well, no, so now we've got this locust tree wired up in stereo, and we're playing the sounds out in the air on a great set of speakers. It's actually really strange because we're playing these sounds out into this little quiet part of the Virginia countryside in a way that begins to almost give an idea of what our environments would sound like if somehow we were able to perceive all these signals traveling through plants, and this is just one plant. So if we somehow had all the plants in our environment wired up, and were playing it we'd hear this incredible cacophony of strange sounds and experience of just walking out and taking a walk down a lane, or in a meadow, would be completely different. [8:59]
9 :00 A C: How much of the other stuff do you think the treehoppers are aware of?
Maybe we all just have a little slice of what's there.
RC: Certainly, We have a little slice. So they're on one plant, and they're going to hear any sounds traveling through their own plant, but the plants act almost like an ear for them because any sounds traveling through the air will induce vibrations in the plant, so they'll be able to potentially perceive bird songs or cricket songs to them in their environment, but again, they're only perceiving a little slice of things......I sometimes imagine what it would be like to walk outside and have sensors just tuned into everything. You'd be listening to the plants around you, and you'd hear airborne sound, and you'd be seeing signals around and if you were in the tropics by a stream you'd be listening to electric fish signals, and something else on the surface, and you'd be completely overwhelmed
RC: It is especially bizarre to have this playing out here on good speakers and to have this sound, seems almost illegal to have this broadcast in the environment. This is not supposed to happen.
AC: Another RADIO EXPEDITIONS first.
RC: You should go out into a meadow and hook onto every plant. ... 11: 27
[ambi] so now the wind has stopped. You hear a lot more signals in these breaks between the gusts of wind. Part of it is probably masking by the wind [ambi] RC: so great. At least on a casual level most of these insects seem to be doing most of their signaling during breaks in the wind.
12:00 AC: Can you interpret that what you're hearing now?
Ambi RC: All the signals that you are hearing are produced by males. The females also signal, but only probably one or two days in their life. They only signal when ready to mate, and they signal in response to a male's call that they Want to mate with them. But males spend most of their adult life signaling. So we're hearing Purring "bddddddddrrrrrr" sounds are sounds that males give either when two males meet each other when they are mate searching on a branch, or When a male is just sitting there in a group of females and another male comes in. So just based on the context, it suggests that they are male -male aggressive signals. 12:55 + ambi
AC: Why do you call these things treehoppers. Haven't seen them hop yet.
RC: The short answer is that that is what everyone else calls them, but why they are called treehoppers
Break/Pause to re-ask question and charge camera batteries
Time code: 14:59/ Clap at 15:03
AC: Why are these called treehoppers, don't seem to hop at all. RC: Running into essential frivolity and irrelevance of common names ....name things so we can talk about them. Most of these don't have individual common names .... how they get name seems to be somewhat arbitrary .... some are on trees, on herbacious plants... don't hop .... I actually don't know...... .
AC: Your real subject is the Umbonia crassicornis -a membracid? RC: Yes, it is a membracid. This is Vanduzea arquata that we have been listening to ...named after a taxonomist named Vandussey ..... .
AC: How was it that you got the idea of listening to these things in the first place? Putting these accelerometers on .....it wouldn't have occurred to me.
RC:17:05 It probably wouldn't occur to me either. I certainly wouldn't want to take the credit for being the first person to suspect that insects were communicating in ways that weren't obvious to us. There is something of a history of studies of insect vibrational communication, and it's become more clear that many groups of insects are doing that. There hadn't really been any published work on treehoppers when I started, but based on many of their relatives, these other hoppers, leafhoppers had been the best studied of any of these little hoppers which are all cicada relatives, and based on the fact that all their close relatives are signaling, I could make the prediction that these would be making vibrational signals as well. Treehoppers were an especially interesting group for me from the communications standpoint because they have so many different forms of social behavior, and grouping, and once you have animals living in groups, then you have all sorts of interesting possibilities for communication, that can create whole new kinds of social interactions, so in this species they live in groups because of their mutualism with ants, so we have this aspect of their ecology -see a causal relation between their ecology of being ant mutualists which then leads them to aggregate and then the fact that they are in aggregations is then going to influence their social behavior and communication. And this is one example of their grouping -this ant species, and this species I studied in my dissertation, Umbonia crassicornis which does have a common name, the thornbug, an example of a very different kind of grouping where they don't interact with mutualists, but they're in sibling groups ........family grows up together on the same stem ..... that's just another example of a social group that occurs in membracids,-so knowing in advance that there was parental care and ant mutualism and other kinds of social groups in membracids seemed like a really interesting group from a communications standpoint and in that sense it completely exceeded my expectations and continue to do so.
AC: Were scientists when you were starting to do this ....
RC: Seven years ago
AC: Were scientists going out and putting accelerometers on stems and saying, come on there's a whole world to hear out there
RC: Sure, there's certainly a few labs -there's a lab that studies spiders -vibrational communications in spiders, and other people have pointed out that there's lots of things using this communication. Not much of this is done in the field. So almost ail of the work has been done in the field, so my efforts here have been more expanding this to look at other groups but are interesting from communications standpoint and to take this into the field and to the tropics, and while I'm doing my research, [ANDREA STARTS LOGGING HERE] I'm always just kind of as a sideline recording anything I can get my hands on, especially for treehoppers and partly just because it's so fun, cause you get these wonderful signals and sometimes you get interesting clues that something interesting is going on you might want to then follow up for later research.
AC: I've seen the video that you shot down in Costa Rica of these thorn bugs, the young and the mother and she's defending them against a wasp.
RC: Sure, that's equally her size, so if you think about these animals they're living always on the surface of a plant and so they're exposed always to predators in three dimensions there's no such thing as shelter, in most cases although we saw those ones living in an ant shelter the other day but that's pretty rare, so mostly they're exposed. And those thorn but families spend most of their immature development which in the egg stage will last a couple of weeks and then three or four weeks to become adults, and then they even stay on the same branch for another week or so beyond that. So they live in this stationary group and they become a very attractive target for predators, and they are, they're very brightly colored, they're distasteful to some vertebrates, like lizards appear to find them distasteful and will reject them, and females defense of going up and kicking is probably not going to be very effective against a vertebrate, but there are lots of invertebrate predators that prey on them, wasps are one of the worst, because wasps for one thing are not eating them, they're just taking them back to the nest where they'll be fed to larvae, so their appetite in a sense is inexhaustible and they also have the cognitive abilities to remember and relocate a group and so they'll come back again and again and again.
0.22.35 -0.23.30 AC: Pluck all the nymphs off...
RC: and one by one, and the females are actually surprisingly effective at defending against wasps so at that field site, maybe three out of four wasp-attacks were foiled by the female where it would maybe go on for several minutes and she'd eventually just persist in, not harming the wasp which she's not capable of doing, but maybe making it probably expensive enough or too expensive to continue trying to get a prey item off this branch and it'll go somewhere else.
AC: But what you found, which was amazing to me, was that the young on this stem are calling to the mother, saying hey we're being attacked come help us out, and she does, she comes and she knocks this wasp away and they're saved. But that's not the kind of behavior that I think of as insects being ...
RC: Well, it's true and that was a surprise to me also, to find that level of communication. There's a couple things that are really pretty surprising about the thorn bugs. For one it's our first really good comparison in insects to the parent-offspring communication that goes on in a vertebrate family such as birds or mammals. There's been a lot of study of this very interesting communication system between parents and offspring in birds where nestlings are pegging for food items and these parents brining in a food item that's small enough that usually can be in theory competed for among the young, and the whole focus of the study of parent-offspring is on the theory of parent-offspring conflict. And how really from the standpoint of the young, they're related to their siblings but they're not clones and whenever you have individuals that are not genetically identical, there's a potential for a conflict of interest, and so behaviorally there's a lot of conflict within birds nest, even siblicide where the larger, the first chick will kill off say another chick in the brood, and so one really surprising, or initially perhaps surprising thing about this insect family is the incredible degree of cooperation among siblings. So in that case,
0.24.54 -0.26.30 [stop to let airplane pass] RC talks about how he will just blab on. RC: You really do have to see these thorn bugs at some point AC: God I'd love to [background, sounds of treehoppers in background] RC they're completely fearless these female and you put your finger next to one of them, she'll come up and kick YOU! And here you are this huge lumbering thing beyond all concept of size for her...
0.26.30 -0.28.45 [background sound of treehoppers] AC: Okay, I'm sorry. You were saying that the RC: We were talking about cooperation AC: But you were saying that the insects, that the nymphs do appear to cooperate in calling. RC: So, right. And so by cooperation it means something that in some sense benefits the group which maternal defense does -it greatly reduces predation. If you take the female away or she disappears, then the predator is successful virtually every time. And if she's there it's successful maybe a quarter of the time or less. So her defense is benefiting the group and the other aspect of a cooperative behavior is that it takes some sort of collective action, which this offspring-parent communication in thorn bugs does. And what happens is that individuals that are say nearest the predators approach will begin to signal, but just one signal by itself is not enough to illicit the female's response -what happens is that other individuals who mayor may not even have perceived the predators approach will then add their signals in immediately afterwards, so you get this wave of signals, everybody's signals pile up in this, into a kind of synchronized unit where if you're looking at it, analyzing it you couldn't possibly pick out one individual signal. So there's still room maybe for some competitive interactions in there by, well, maybe some individuals don't signal-but it's cooperative and there's other groups of tree hopper offspring that I'm studying in the tropics where there are other examples of cooperation among siblings, and it makes sense in the, in terms of their ecology that they would be cooperating, that there is some common interest there but it's perhaps was unexpected because so much of the work on parent-offspring communication was based on birds and there the interactions -the dogma anyway is that they're strictly competitive.
0.28.45 -0.30.31 [Treehoppers in background] AC: Well it may make sense in theory, but, and maybe it's just because I am not a scientist I don't really study insects, but it just sounds so un-insect like to me. It's just not what I expect. RC: Well, these insects really are almost like little mammals or birds in a way, in fact thorn bugs, some of their signals sound like chickens maybe or they remind me in some ways of a vertebrate family, and the other things that I really get struck with from having studied insects, after having studied vertebrates a little bit early on in my career, is that often people tend to think of insects as kind of blind dumb lumbering robots that are, with fairly simple stereotyped behavior, and in fact they're not simple at all.-they're just as complex as vertebrates -they really are just as complex in their behavior as vertebrates they're just very different, in many ways, and similar in other ways as you're pointing out. But I think that as we learn more about insects and if you're more familiar with them then you begin to break down some of these ideas of a real division between invertebrates and vertebrates, certainly hearing their signals that don't sound very insect like, but of course they're very insect-like -these are insects! And so really we were just seeing only a small slice of the picture and so sure parental care or cooperation among offspring doesn't seem very insect-like, but of course it is very insect-like because these are insects...
AC: It's insect-like to them, we just don't recognize it!
0.30.31 -0.30.49 Stop for airplanes.
0.30.49 CLAP SLATE
0.30.49 -0.31.53 And AC and RC talk about the plan of action for the day.
0.31.55 -0.32.06 [camera stuff. They call this tape 4]
0.32.07 CLAP SLATE
0.32.07 -0.33.19 AC: What we're talking about doing is going out into the meadow with Rex and a couple of nets, actually big butterfly nets, to gather more insects, and we're going to take them and put them on another kind of plant, a goldenrod, and we're going to listen to those, because a lot of the things out there are going to be making sound. Some kind of sound [background sound of treehoppers]
[good ambi with that]
0.33.19 -0.34.20 AC makes treehopper sounds, laughs, says they sound like kittens. AC: When people hear this they're going to be writing you Rex, saying, gosh where can I get some of those treehoppers from ... I want to adopt a treehopper! RC: Well, ... [treehopper sound over ambi -birds and crickets.
0.34.20 CLAP SLATE
0.34.20 -0.34.53 Treehopper shuffle LOUD, everyone reacts,
0.34.53 -0.36.19 Ambi. Light wind through grass, crickets and birds. [very light airplane]