Readers’ wildlife photos

January 12, 2021 • 8:00 am

Thanks to several readers for heeding my request for photos. I always need pictures, though, so do think of sending me some if you’re in possession of good ones.

Today we have regular Mark Sturtevant with his customary lovely and informative pictures of insects. Mark’s comments and IDs are indented; click on photos to enlarge them.

First up is one of our larger insects, the summer fishfly. For scale, it is approximately the size of your index finger. Fishflies are members of a somewhat obscure order, the Corydalidae, and in various respects they are fairly primitive insects even though they have complete metamorphosis with a larval and pupal stage.

An unusual thing about the pupa is that they can crawl around. This particular species is Chauliodes pectinicornis, and I found it at some lights that were left on overnight at a local park. If you are wondering about the white spot on its head, that is one of its large and reflective ‘simple eyes’.

Next up are two larvae that strongly resemble caterpillars, but are actually the vegetarian larvae of wasps known as sawflies. Sawfly larvae and caterpillars (the larvae of butterflies and moths) are examples of convergent evolution. The first is Macremphytus testaceus, on dogwood, and the second is Allantus cinctus. This species is a pest on cultivated roses, although this one was in a forest, possibly on wild rose.

At one of the parks I visit, there is a community garden area where locals can grow various crops. It is always profitable to prowl up and down the narrow lanes between the gardens. One day I came across this large and strange bee that was foraging along a row of sweet peas. The extra furry underside of its abdomen identifies it to the family Megachilidae, and familiar examples of these bees are leaf-cutter bees. But this was a big ‘un, easily twice the size of those bees. So what is it? This is the giant resin bee (Megachile sculpturalis sculpturalis), an introduced species from Asia. The bee was presumably provisioning a nest in a wooden retreat somewhere, and in there larvae will be raised in separate cells made from mud and tree resin. 

At the same park I got a very big surprise. I noted what looked like a simple leaf gall, only it had this suspicious symmetry. So I touched it, and it immediately unfurled into this weird little spider! This is a species of bolas spider, specifically Mastophora yeargani. These are orb-weaving spiders that do not build typical webs, but instead sit on the end of tree branches at night to dangle a single silk strand with a glob of sticky glue at one end. When a flying insect comes close, it flings this ‘bolas’ at the insect, snagging it in mid-air and then reeling it in for a meal. I did not know they were in Michigan (none are recorded in BugGuide, so I will be sending this to them).

The best parts of this story are colorfully told in this True Facts video by Ze FrankDo watch it, and someone can then report back and tell us what those loose flakes are on the spider. 

Next up is a well concealed flower crab spider that got quite a catch. This one looks to be in the genus Misumenoides, based mainly on the arrangement and relative sizes of the eyes.

Moving back to Hymenoptera. A place I call the Magic Field hosts many wildflowers, including spotted beebalm (aka horsemint), and these are super attractive to large solitary hunting wasps. The wasps include a large species of spider wasp (Anoplius americanus), so-named because it hunts spiders, paralyzing them to feed to their larvae. This spider wasp is very difficult to photograph (at least for me), since they forage through the flowers at break-neck speed—even faster than the swift golden digger wasps and great black wasps that also frequent these flowers. So here I cheated a little by catching a spider wasp in a net, and I then attempted to immobilize it for a time with COfrom a few Alka Seltzer tablets. This old trick of using COas an insect anesthetic does not always work, and that was the case here since the wasp was slowed only a little. She flew off in a few seconds, and I was lucky to get this single acceptable picture.

The Magic Field also hosts the main prey for the above spider wasps, a burrowing wolf spider (Geolycosa missouriensis). These large spiders are seldom seen during the day, except they occasionally sit at their burrow entrance in the early morning. Of course they will retreat underground when approached, but will pop back up after several minutes once they think the coast is clear. Although I don’t normally bother with a tripod, it was helpful here to remotely get a low-angle picture of a wolf spider at their burrow entrance. The next picture shows the result. These wolf spiders are not fans of spider wasps! I expect many are taken, although I have never seen it happen.

Finally, sometimes readers are curious about equipment that is used to photograph arthropods. In truth, almost any dslr or mirrorless camera and macro capable lens will take excellent pictures. But the last picture shows how the above wolf spider was photographed. Come to think of it, all the pictures up there were taken with this rather old camera, the Canon t5i, and the lens is the Canon 100mm f/2.8L macro lens. That’s a fancy lens, but any true macro lens will be essentially as good. You can see in the background the external flash that I normally use for this camera, which is the Kuangrendual head flash with a couple of instant-noodle soup bowls mocked up to be diffusers. That flash was too cumbersome for this particular situation, so I had to improvise.

 

Readers’ wildlife photos

January 4, 2021 • 8:00 am

Tony Eales from Queensland came through with three batches of photos. Today we see the first one, whose theme is a subject dear to my heart—mimicry. Tony’s notes and IDs are indented; click photos to enlarge them.

Remember that in Batesian mimicry an edible “mimic” evolves to resemble a visible and toxic or dangerous “model,” protecting the former from predation by a third, predatory species that has either learned or evolved to avoid the model. In Müllerian mimicry, on the other hand, two toxic or distasteful species evolve convergently to resemble each other, which gives a selective advantage for the survival of each: it’s easier for a predator to learn and avoid one pattern rather than two.

Some recent examples of mimicry that I’ve photographed.

The first two are an example of Müllerian mimicry. Both the Velvet Ant (actually a wingless female wasp) Aglaotilla sp. and the Green-head Ant (Rhytidoponera metallica) possess a pretty nasty sting and inhabit the same habitat, leaf litter and tree trunks. A predator’s experience with one will inform their future interactions with the other.

Next is an Ant-like Flower Beetle, Anthelephila sp. which are Batesian mimics of ants. They are not close mimics but the ant-like shape and the colour patterns are similar to many ant types— e.g., these Iridomyrmex purpureus Meat Ants—and probably confers some advantage. Given how common and varied ants are in the Australian bush, predators probably tend to just ignore anything ant-like.

 

Meat ants:

The next two are beetles mimicking beetles. Episcaphula rufolineata is in a group called the Pleasing Fungus Beetles (family Erotylidae) which, as the name suggests, feed on fungus and are often quite colourful.

Scaphidium exornatum, on the other hand, is in the Scaphidiinae, the Shining Fungus Beetle sub-family of Rove Beetles. It also is found feeding on fungus in the same forests as E. rufolineata.

As you can see, they look very, very similar and without knowing what chemical defences either have, it’s hard to know if this is Batesian or Müllerian and which species was the model and which the mimic. S. exornatum doesn’t look like a typical Rove Beetle, but there are some strange looking Rove Beetles without any mimicry going on (try Googling Diatelium wallacei some time).

Not only are these two mimics not in the same beetle family, they are in different infraorders.

The next set of beetle mimics broke my brain. I don’t even know what is real any more. Lycid beetle mimicry is very common, among other beetles and also insects as different as flies and moths but the mimicry here is so perfect, I’m reluctant to ID another Lycid.

Trichalus ampliatus is a fairly common lycid beetle where I live, known as the Red-shouldered Lycid Beetle. I photographed one just the other day and put it up on iNaturalist as T. ampliatus only to be informed that no, what I was looking at was a member of the False-blister Beetle family Oedemeridae. To me the only difference I can see is the mouth parts. The texture of the wing covers, the look of the antenna, the colour, even the way it holds itself is a perfect match. Fittingly the genus is Pseudolycus.

T. ampliatus:

Pseudolycus sp.:

Last, a case of aggressive mimicry. [JAC: An animal evolves to further its aggressive behavior; in this case, a predator evolves to resemble its prey to fool them.]

The larva of the small ladybird known as the Mealybug Destroyer Cryptolaemus montrouzieri looks like a mealybug or scale insect. These bugs suck plant juices and excrete sugary waste that ants collect. The ants in turn defend the mealybugs from predators. But the Mealybug Destroyer larva looks like a mealybug and perhaps smells like one too. In addition, the waxy filaments are a good defence against ant aggression as well as protecting these insects from over-enthusiastic ant attention.

C. montrouzieri:

Mealybug:

Readers’ wildlife photos

December 29, 2020 • 8:00 am

Again I importune you to send in your phots. In a few days the situation will be dire!

Today, though,  we have a diversity of photos from Rachel Sperling, including Lepidoptera, landscapes, and herself. Her captions are indented; click on photos to enlarge them.

Here are a few wildlife photos for your site, taken around New England and New York this summer and fall.

Monarch butterfly (Danaus plexippus) on butterfly bush (Buddleia davidii) in upstate New York this summer:

Spicebush Swallowtail (Papilio troilus):

White admiral (Limenitis arthemis):

Hummingbird clearwing (Hemaris thysbe), a moth in the Sphingidae (hawkmoth) family. They really do resemble hummingbirds at first glance and they’re hard to photograph because they don’t stop moving! Not for me, anyhow.

Common loon (Gavia immer) on a small lake in the southern Adirondacks this August:


White oak (Quercus alba) on the Appalachian Trail in Pawling, New York. This particular oak, known as the Dover Oak, is at least 300 years old and is thought to be the biggest oak (if not the biggest tree) on the entire 2,190-mile trail. I guess I AM an unabashed tree-hugger.

This black birch (Betula lenta) also known as a sweet birch or spice birch, is also on the AT in New York … and is clearly possessed by some kind of angry spirit. Consensus among hikers is that it was hit by a shotgun shell some years back (it’s still alive). I’d be angry too.

Smooth rock tripe (Umbilicaria mammulata) on a boulder on the AT in New York, though I’ve seen it almost everywhere I’ve hiked in the northeastern US. [JAC: This is a lichen.] So-named because of its resemblance to tripe (cow’s stomach) it’s apparently edible as a last resort. (According to accounts, George Washington’s men ate it to keep from starving at Valley Forge.)

I don’t know if you’re still collecting photos of readers, but this is me (Homo sapiens) on the summit of Mount Mansfield, highest peak in Vermont, trying not to get blown over by the high winds (I think it was gusting around 30mph, maybe more). There wasn’t much of a view at the summit, but once I began my descent, the clouds dispersed and it got better. This was back in late September. When I’m not hiking, I’m a librarian at a university in Connecticut.

“I didn’t mean to climb it, but got excited and soon was at the top.” – John Muir

Reader’s wildlife paintings

December 25, 2020 • 9:15 am

I wasn’t going to put up a readers’ wildlife feature today, but Jacques Hausser from Switzerland sent me a series of lovely beetle drawings that he did to illustrate Christmas cards. So here’s his Christmas card to us. Jacques’ commentary:

Just before the era of digital photography, I realised that I didn’t know anything about entomology. To begin with insects, I decided to draw (and to try to identify) some coleopterans. This virtuous decision didn’t survive the arrival of my first digital camera, and I turned to photography.  During this cloudy and rainy December, I looked back at these old drawings, and I thought it was a good idea to use them to make some Christmas gifts. Then, as I hadn’t sent any valuable photos to Jerry for a long time, I thought I’d submit the result to “Readers’ wildlife photos” even if they are not photos. I arranged the drawings in three plates without respect for the relative size of the beetles or their systematic position. And a caveat: some names may be old, and I cannot exclude a mistake!
There are three plates (in order), and I’ll put the identifications of the beetles below the fold. Click to enlarge.
Plate 1:

Plate 2:

Plate 3:

Click “read more” for the IDs:

Continue reading “Reader’s wildlife paintings”

Readers’ wildlife photos

December 22, 2020 • 8:00 am

Please keep those photos coming in if you can, as they get depleted quickly. Today’s batch comprises insect photos from regular contributor Mark Sturtevant, whose notes are indented. Click on the pictures to enlarge them.

Here are more pictures of insects taken over a year ago.

The first picture shows an odd – looking group of larvae feeding on wild bergamot. These are tortoise beetle larvae, well known for their habit of carrying a ‘fecal shield’ as a deterrent against their various enemies. They will even wave their repugnant abdomen at you when disturbed. The adult of this particular species (Physonota unipunctata) is shown in the link above.

Speaking of beetles and fecal shields of sorts, the strange object in the next picture is a case-bearing larva of a Chrysomelid beetle. Larvae in the genus Neochlamisus crawl around in a protective case made of their own poo. You can sometimes see their legs or head sticking out, but this one was not cooperating. One again, the link shows the adult beetle. Interestingly, the adults are considered to be caterpillar-dropping mimics (!)

Let’s continue with beetles, as I have an inordinate fondness for them. The next three are all “longhorn” beetles, named after their long antennae, and these species are commonly seen feeding on pollen from flowers. The first two are Typocerus velutinus and Brachyleptura champlaini.  The third photo shows Clytus ruricola, described as a kind of a ‘wasp beetle’ since they mimic wasps. I think it most closely resembles a small potter wasp. Wasp beetles move around rather quickly and erratically, and in doing so they really do manage to look wasp-like.

Next is a picture of a leafhopper nymph that I retrieved from the trumpet vines in our backyard. The picture is focus-stacked from 7 pictures taken by hand from a staged setting. I think the species is Jikradia olitaria.

Leafhoppers are related to insects known as planthoppers. Knowing the difference is a deep dive into trivia, but among the distinguishing traits are these: leafhoppers are a single but large family, and they are powerful jumpers with enlarged hind legs that have movable spines. Their antennae arise in front of the compound eyes. In contrast, Planthoppers are actually a consortium of families. They tend to be laterally flattened, are not powerful jumpers, and what spines they have will be fixed in place. Antennae emerge below the eyes. There are other differences as well.

Anyway, the strange planthopper shown in the next picture is in the Derbidae family, and is called Apache degeeri. I’ve featured it here on more than one occasion, but they are so odd they deserve the attention! Before it flew off, I managed to get in two pictures by hand, while standing, and these were later stacked together to make this one picture. Dumb luck that it worked. The weird ‘mouth’ is really a curly antenna.

Next up is a rather wonky looking caterpillar that is definitely a bird-dropping mimic. I had long ago identified it as the larva of the red-spotted purple butterfly (Limenitis arthemis), but later I stumbled upon pictures of the larva of the viceroy butterfly (Limenitis archippus), and it seemed identical! This was very strange since the adult butterflies are very different.

I looked into this mystery and learned that the two butterfly species are closely related, and yes, their caterpillars are hard to tell apart and they also feed on many of the same host plants. The species are sufficiently related that they will even form interspecies hybrids in the wild, as shown here. This is very weird to see!

Anyway, after much deliberation I’ve decided this is a viceroy larva, owing mainly to a few extra spikes on the head. But I could be wrong.

The last picture is a group of the above butterflies having a “puddle party”. This is where they feed on muddy ground to imbibe amino acids and salts. An interesting detail about this behavior, which is seen in many butterflies, is that puddle partygoers are usually males. The trace nutrients are transferred to females during mating, and some are incorporated into their eggs.

True facts about army ants and their associates

December 17, 2020 • 2:30 pm

ZeFrank’s videos are getting better and better as he adds more biology, talks to experts in the field, and puts in professional videos taken by biologists. This one, about army ants, is especially good. Ants are strange anyway, but army ants, which have no permanent nests (often living in vans down by the river), are among the weirdest ants. We have them in the U.S., too, though you don’t often see them and they’re being extirpated by imported fire ants.

There’s a new book out on army ants (click on screenshot below), and though I haven’t read it, my ant friends (not ants, but people who work on them) say it’s excellent and especially well written.

As I said, army ants have no permanent nests, and are always on the move, though they move in a punctuated fashion, sometimes staying put for a while, but never living underground. Each nest has a single queen, and if that queen is killed by predators or dies, the nest is a goner, for the colony simply can’t function, plus it loses the only individual who can produce new ants. Male ants (drones) do no work, but march with the colony, and when it’s time to reproduce they fly away (they have wings) and find virgin queens in another nest.

Besides the reproductive queen, there are a few non-mated queens in each nest, and those come about when workers “decide” to give a few larvae extra food (probably richer food, too, as is done with “royal jelly” in bees). Those female larvae, coming from fertilized eggs (males, as in all Hymenoptera, develop from unfertilized eggs), become queens, and, when they’re ready to mate, emit a pheromone. That pheromone attracts the winged drones from other swarms, who fly to the other swarm and mate with the virgin queens, dying soon thereafter.

This produces an army-ant swarm with more than one queen, and that’s an intolerable situation for the workers. Thus such swarms undergo fission, with the newly-mated queens taking off with a bunch of workers to found their own swarm.  As with bees, the male ants are true drones, doing no foraging and serving only to contribute sperm to unfertlized queens.

One other note: Army ant queens are huge compared to workers, and would make tasty prey for a bird or other predator. That’s why, when the colony is on the move, the queen is surrounded by a retinue of workers, especially the soldiers with their fearsome jaws. Look at this size difference! (This is Eciton burchellii, a neotropical species in the genus most featured by ZeFrank):

Source. Photo by Daniel Kronauer

Here’s a pinned soldier of the species. Look at those jaws!

AntWeb.org image

The queen can lay up to 100,000 eggs in 20 days, and that’s why she needs that huge abdomen.

Here’s a fascinating Attenborough video on army ants:

Fruit Fly Central: the Bloomington Drosophila Stock Center

December 16, 2020 • 11:15 am

Imagine my surprise when several readers sent me a longish article from the New York Times about the Bloomington Drosophila Stock Center at Indiana University (click on the screenshot below). For, when I worked with flies for over four decades, I used their services—and their fly stocks—constantly. Much of my work would have been impossible without the strains they provided, which involve various kinds of mutations, chromosomal aberrations, genetically engineered strains, and so on. Moreover, as the article notes, Drosophila is the best animal model we have for genetics. It’s been useful not just in pure research, but in applied work. As the NYT notes:

Studying these slight mutants can reveal how those genes function — including in humans, because we share over half of our genes with Drosophila. For instance, researchers discovered what is now called the hippo gene — which helps regulate organ size in both fruit flies and vertebrates — after flies with a defect in it grew up to be unusually large and wrinkly. Further work with the gene has indicated that such defects may contribute to the unchecked cell growth that leads to cancer in people.

Other work with the flies has shed light on diseases from Alzheimer’s to Zika, taught scientists about decision-making and circadian rhythms and helped researchers using them to win six Nobel Prizes. Over a century of tweaking fruit flies and cataloging the results has made Drosophila the most well-characterized animal model we have.

And so I’m glad the Center finally got some recognition, which is well deserved. These people have labored diligently—not just accumulating strains of flies, which now number 77,000 (!), but sending them out to workers throughout the world and—the most labor—making the food that fills the fly vials to keep the strains alive, and changing each stock (kept in replicates to preserve them) every couple of weeks. You can’t freeze Drosophila to preserve them alive like you can bacteria, and so keeping the cultures going requires constant attention. I had hundreds of strains in my own lab, and spent many hours a week just changing exhausted vials into fresh vials. (The article calls this “flipping flies”; we called it “changing flies.)

So my kudos to the center, which kept going—as it had to, if Drosophila genetics were to survive—during the pandemic. The Center’s work during the pandemic is a large part of the NYT story.

Now though there are several thousand of Drosophila species in the wild, only one—Drosophila melanogaster—is kept in Bloomington, for that’s the species that fortuitously was developed by Thomas Hunt Morgan, my academic great grandfather, when he began Drosophila work at the beginning of the 20th century. And that’s the species used as the animal model today. Here are all the various kinds of stocks you can order:

That’s a lot bigger list than existed when I got into the game: we had no genome editing stocks, fluorescent proteins, or binary expression systems. We had mostly chromosomal aberrations, deficiencies and duplications of genes or chromosome segments, and, of course, the classical single-gene mutations. Here are some single-gene mutants (from Wikipedia). “Normal” or “wild-type” flies, as you catch them in the wild, look like the one in the middle at the top, but with brick-red eyes (see second photo below).

D. melanogaster multiple mutants (clockwise from top): brown eyes and black cuticle (2 mutations), cinnabar eyes and wildtype cuticle (1 mutation), sepia eyes and ebony cuticle, vermilion eyes and yellow cuticle, white eyes and yellow cuticle, wildtype eyes and yellow cuticle.

A “wild type” fly from the NYT article (photo by Bob Gibbons):

I’ve used all of these mutations at different times, often to see if they were identical to similar-appearing mutations that I found in close relatives that could cross with D. melanogaster and produce offspring. (For example, if I found a “sepia”-like eye color in the sister species D. simulans, I’d cross it to known D. melanogaster sepia; if the offspring all had brown eyes, it was the same mutation. This is known as a “complementation test.”)

Here are a few more photos from the article (captions from the NYT). Some of the 77,000 stocks, kept immaculately:

Thousands of fruit fly stocks at the stock center.Credit…Kaiti Sullivan for The New York Times

Changing flies! Every experimental drosophilist spends much of their life doing this:

Stockkeeper Micaela Silvestre-Razo flipped flies in a spare room of the stock center. Credit: Kaiti Sullivan for The New York Times

Here’s a historic stock: white-one, a white-eye mutant discovered by Thomas Hunt Morgan in 1910. Morgan found that when you crossed white-eyed females to “wild type” males, all the male offspring were white and all the female offspring had normal red eyes. In contrast, if you crossed white-eyed males to wild-type females, you found that all the offspring were red-eyed, but the female offspring from that cross produced half white-eyed males and half-red-eyed males. This weird pattern comes because white is a recessive gene on the X chromosome: it’s “sex-linked”—like red-green color blindness or hemophilia in humans.

You can read about Morgan’s study of white here, and see his 1910 paper here. (He won the Nobel Prize in 1933 for his work on classical genetics, but split the money with his “boys”—his extremely talented group of researchers who occupied the “fly room” at Columbia University.)

The white-one stock below has just been put into fresh vials of medium, which is made with water, soy meal, cornmeal, yeast, and a usually a preservative. Within 10-12 days at 25°C, you will get a new generation of adults, as the eggs are laid on the food, the larvae (“maggots”) hatch and burrow into the food (also eating it), and then crawl onto the sides of the vials to spend 4-5 days as pupae (the fly equivalent of a cocoon) before hatching (“eclosing”) into new adults. After about two generations the food is used up and you have to “flip” the vial.

The vial on the right doesn’t seem to have been cleaned very well, as there are old, empty pupal cases still adhering to the walls, which would be washed off during a proper cleaning.

Here are old, grotty, spent vials (the header of the NYT article).

Here’s the original “fly room” at Columbia where the Nobel-Prize-winning work was done. Six or seven researchers crammed into this space, and food (at that time made with bananas) was also prepared here. Only Morgan himself, as the boss, was allowed to eat one of the bananas. You can see a microscope for examining flies in the foreground, and the milk bottles full of fly food on the table:

Here’s Calvin Bridges in the Columbia Fly Room. Bridges, a wickedly handsome man with a colorful and rogue-ish life, was a fantastic researcher and made many contributions to modern genetics:

This book will give you more information about the early history of Drosophila genetics and how it influenced today’s “Drosophila culture”:

Now a lot of my fly work was done with species other than D. melanogaster, though they were close relatives. That’s because I worked on speciation, and to do the genetics of speciation (i.e., finding out which genes and how many of them change during the split of an ancestor into two or more descendant species), you need several species, ideally ones that can be crossed. Since the Bloomington Center contained only D. melanogaster, I got my other species by collecting them myself, getting them from colleagues who collected them, or ordering them from the National Drosophila Species Stock Center, then at Bowling Green State University in Ohio but now at Cornell University.

I see that the NDSSC still keeps some of the mutant cultures I found in the relatives of D. melanogaster, but, sadly, most of them have been lost, since they used to concentrate only on wild-type flies of different species and didn’t want to take the mutations I had laboriously found and identified. But, like the Bloomington Center, they were a huge help to me when I worked on speciation, and I want to thank them as well.

I could go on and on and on about the Centers and their value and their stocks, but I’d best stop here because it’s lunchtime. I’ll just add that I once combined a mutant called groucho (which had extra bristles over its eyes) with proboscipedia (a fly whose mouthparts transform into leglike structures) to get a Groucho Marx fly with bushy eyebrows that looked as if it were smoking a cigar.

First report of tool use in honeybees: a native species uses dung pellets to repel predatory wasps

December 13, 2020 • 10:00 am

In my book Why Evolution is True, I begin the chapter on natural selection (Ch. 5) by describing how native honeybees in Asia defend themselves against the attacks of a predatory Asian giant hornet (Vespa mandarina), a species of huge and fearsome hornets that has now invaded North America. (You’ve surely heard of them as “killer wasps” or “murder wasps”: they are so big, vicious, and venomous that their stings kill several dozen people a year.)

These hornets can completely destroy a honeybee hive, as the hornets are impervious to stings and have powerful jaws that can decapitate bees at a rate of more than one a second. After raiding a nest and killing all the residents in an hour or two, the wasps slurp up the bees’ honey and then carry off the bees’ brood to feed their own larvae, who are ravenous for meat.

Wasps find the honeybee nests via scouts, who, upon encountering a nest, mark it and the surrounding vegetation with a pheromone, which somehow attracts other wasps to the nests, often leading to a big raid. (Wasps may also follow the scouts to the nest.)

But natives bees have evolved a counter-adaptation: “balling”. Sometimes, when a scout wasp lands on a nest of native bees, the residents lure the scout inside, where a swarm of bees awaits. They pounce on the scout, surrounding him with a big ball of bees, and proceed to vibrate their abdomens. This raises the temperature inside the ball  to 47°C (117° F), a temperature that cooks the wasp to death within 20 minutes but doesn’t hurt the bees. Here’s a short video of a bee ball killing a hornet, which you can glimpse in the center of the vibrating mass:

It’s a clever and evolved strategy for disposing of a scout before it has a chance to alert other wasps. The wasp’s fearsome behaviors, and the “arms race” that has led to “balling” by the native bees, is the example I use to introduce natural selection.

As you might predict, introduced bees, like the European honeybee (Apis mellifera), haven’t been in Asia long enough to evolve the balling strategy, and thus are much more likely to have their nests destroyed by wasps. Natural selection takes time.

But some native honeybees have evolved (or perhaps learned) another defense against wasps, and this is described in a new paper in PLOS ONE. It in fact involves the first known use of tools in honeybees. Click on screenshot below to read it (pdf is here, reference at bottom):

The title pretty much tells the tale. Here’s the victim honeybee, Apis cerana, a native species (click all photos to enlarge them):

And the main predator studied, Vespa soror, another large fearsome wasp that raids and destroys  the bees’ nests. These are big ‘uns, with lengths ranging from 26-46 mm (1-1.8 inches)

The study was done in Vietnam using commercially kept bees with wooden nest boxes. The researchers observed that many of the nest boxes were speckled around the entrances with tiny raised spots of animal dung, as in picture A below. They observed bees collecting dung (B; note that the B is experimentally marked), and immediately conveying it to the nest entrances, where they worked it into tiny mounds around the entrance.

Photo C shows a worker bee (these are of course all females) with a bit of dung in its mouth. They don’t eat it, but take it to the nest entrances. D shows another marked bee, with the orange spot, plastering the dung by the entrance.

Attacks by wasps and the results are shown in photos E (an attack by six V. soror workers), and F, which shows how the wasps actually enlarge the entrance by chewing on the wood, presumably to allow easier access to other wasps. Those wasp jaws are strong!

The researches did a number of manipulative and observational experiments to answer some questions about this behavior.  I’ll summarize them briefly:

a.) The fecal spotting is widespread. Over the ten-day observation period, the number of hives accumulating spots went from about 10% to between 40% and 90%. This is, perhaps, because the researchers were working during the wet season, when wasp attacks are most frequent.

b.) Attacks by the wasp prompt more fecal spotting of the hives. The spotting occurs either during an attack of wasps who don’t destroy the hive, after an attack when experimenters prevent further attacks, and for at least three days after an attack. The continuation of spot-making after an attack is used as one clue about how the spotting works (see below).

c.) Attacks by a less dangerous wasp species prompt less fecal spotting. Wasps in the species V. velutina don’t attack nests en masse like V. soror, but simply pick up single bees in flight. Sure enough, even when encounters between the bee and these two species were equally frequent, there were significantly fewer fecal pellets deposited by the bees after V. velutina than after V. soror encounters. This of course makes sense if the fecal pellets are put in place to reduce the deadliness of wasp attacks.

d.) Extracts of the wasps’ pheromone glands prompt the bees to make more fecal spots. The researchers pinned pieces of filter paper to the nest saturated with either an ether control (it would evaporate, though) or an extract of the “van der Vecht glands” from the wasps, which are thought to be where the wasps’ “scouting” pheromones are made. (They should have used an organic non-wasp chemical that wouldn’t evaporate.) This chart shows the significant increase of spots prompted by using the gland extract as opposed to the ether control (caption from paper); the experiment lasted only six hours.

This suggests that the wasps’ marking of the nests, as opposed to wasp presence alone, is a main force leading to fecal spotting. You don’t need wasps to create the bees’ behavior, just pheromones.

e. Fecal spotting keeps the wasp V. soror away from nest entrances. The researchers divided nests into three categories with respect to the level of fecal spotting: light, moderate, and heavy, shown respectively by the three colors of bars in the figure below. When they measured the behaviors of the hornets in several ways (duration of visits, —which include visits in which wasps don’t land on the nest box), duration of time wasps were landed on the hive, duration of time at the entrance, and duration of chewing at the entrance, every single index of aggressive wasp behavior decreased with increased spotting. The asterisks below show significant difference between groups, almost certainly due mostly to the light spotted nests versus the group (moderately spotted + heavily spotted).  This shows that the fecal pellets do something to reduce wasp predation.

There are, as the authors note, lots of questions that remain. I’ll deal with only three here:

1.) How, exactly, does the dung reduce wasp visits? There could be two ways. First, the dung could act as a deterrent to the wasps, perhaps via its odor. The researchers could, I suppose, test this directly in the laboratory, but that wasn’t done. The other way is that the dung could mask the “scouting pheromone” deposited by wasps or somehow overpower its odor, reducing wasp attraction. This could in principle be tested by looking at the frequency of wasp visitation on nests where no pheromone had been deposited. But that would be hard to do, as it requires constant monitoring of nests.

The authors favor the idea that the dung itself is a repellent, as the bees continued to add spots around the hive entrance for several days after an attack. (The presumption is that the pheromone odor would have disappeared by then.) But the dung could of course serve both functions.

2.) How did this behavior evolve? I’m assuming here that this is an evolved rather than a learned behavior, though part of it may be learned. There have been reports of this and other wasp species smearing plant juices around the entrances of hives, perhaps using the plants as either a wasp repellent or a pheromone masker. As the authors write:

Fecal spotting is behaviorally analogous to observations of “plant smearing” by Acerana japonica in Japan, which occurs in response to attack by Vmandarinia . In this recently described behavior, workers carry gnawed plant material in their mandibles and then smear their juices around nest entrances, leaving dark stains. Although we did not study how filth foraging is organized, we observed several workers performing “emergency” dances outside of hive entrances, a behavior that recruits nestmates to smear plant material in Japan. It is fascinating that Acerana has been observed foraging for plant material in the northern part of its range and for filth (feces) in the southern part of its range to defend nests against attack by different, but equally deadly, mass-attacking Vespa predators.

It’s possible that the ancestral behavior here is smearing plant juice around nest entrances, especially if you think that animal dung was not as prevalent in the time before bees were kept in boxes by humans or didn’t live around domestic animals. From there it would be a simple step to evolve collecting dung instead of plants, which is easier since you don’t need to gnaw the dung. It’s not clear, of course, whether either behavior is genetic or learned, but I suspect both have a least a partial genetic component. That itself could be tested in principle by seeing if the behaviors appear in bees that are raised “naively”, without the chance to learn from other bees. I don’t know if that is possible.

3.) Is this really tool-using by bees? The authors define “tool use” according to four criteria of Benjamin Beck as published in a 1980 book: an animal uses tools if it uses an environmental object (a piece of dung); if it alters the object in a way to make it more efficient to use (the bees mold the feces and apply them to nest entrances); if the user holds and manipulates the tool before or during use (collection and carrying of feces to nest and deposition as spots); and if the user “effectively orients the tool” (bees place the spots almost exclusively around the nest entrance, which is where predatory hornets enter).  Since the bees do all of these things, the authors conclude that this is a case of tool use—the first known tool use in honeybees (a lot of other insect species use tools).

I’m not so concerned about whether this behavior falls into the category of tool use, whose criteria vary from investigator to investigator, as I am to understand how the “tools” work and how the spotting behavior evolved.

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Mattila HR, G. W. Otis, L. T. P. Nguyen, H. D. Pham, O. M. Knight et al. 2020. Honey bees (Apis cerana) use animal feces as a tool to defend colonies against group attack by giant hornets (Vespa soror). PLOS ONE 15(12): e0242668. https://doi.org/10.1371/journal.pone.0242668

Here are the leaf mimics!

December 7, 2020 • 3:00 pm

Did you spot all nine leaf insects in today’s photo from the New York Times taken by Hsin-hsiung Chen? Here’s the reveal (click photo to enlarge):

If you can’t see them, it’s a clue that sharp-sighted birds, who hunt these using vision, can’t easily see them either.

Spot the leaf insects!

December 7, 2020 • 12:30 pm

The pictures of leaf insects below come from a cool science story in the New York Times about this fabulous family of fantastic mimics (Phylliidae). The story has a lovely twist, as the females look like leaves while the males look like sticks, and for many years scientists thought the sexes were members of different species. In fact, they were named as different species. There’s one clue that something’s amiss, though: you shouldn’t find that every individual of your species is a female—or a male.

There are only three ways to identify such different-looking sexes as members of the same species. First, you can catch a male and female in copulo. That isn’t on for these species, as the sexes are both hard to see—so cryptic that some experts on the group have never seen a living individual in the wild.

Second, you can look at the DNA, for males and females should have virtually identical DNA—much more similar than the DNA of different species, even closely-related ones.

Third, you can do what was done in this case: rear a clutch of eggs in the lab, and discover that from that clutch both sexes, having drastically different appearances, emerge. And that’s how they identified the conspecific males and females in this case. Do read the story at the link above.

For our purposes today, you can see the preciseness of female mimicry by looking at the photo below. It contains nine leaf insects. Your task, which isn’t easy, is to find them all.

The reveal will be at 3 pm Chicago time. (The photo is by Hsin-hsiung Chen.) Click the photo to enlarge and make hunting easier.

Just to show you what these marvelous mimics look like, here’s a close-up of one (caption from the NYT article):

A female Phyllium asekiense, a leaf insect from Papua New Guinea. Like many leaf insects, P. asekiense was known only from female specimens.Credit: Rene Limoges/Montreal Insectarium

h/t: Jean