Readers’ wildlife photos

May 28, 2021 • 8:00 am

I am running dangerously low on photos, and worry that I will have to cancel this feature or make it more sporadic. If you have good wildlife (or “street”) photos, please send them in pronto. If you’re an American, you have a long weekend coming up to peruse your photos.

All photographers’ words and captions are indented, and you can enlarge the photos by clicking on them.

We have a potpourri today, the first coming from reader Jonathan Storm.

I found this dead grasshopper on an eastern hemlock in the Blue Ridge Mountains of South Carolina. It was killed by an entomopathogenic fungus last summer or fall. These fungi are parasites that infect and eventually kill their insect host. Last summer, a fungal spore landed on this grasshopper and worked its way into the body cavity. The fungus then grew and spread until it killed the grasshopper. Several fruiting bodies of the fungus later grew out of the grasshopper and released their spores into the breeze. Some of these spores will then infect a new insect host and the cycle continues.

A gorgeous Cyclops moth (Antheraea polyphemus) from reader Smith Powell, photographed by Jennifer Lawson:

My granddaughter, Jennifer Lawson, photographed this moth on 02 May 2021 in the family yard in Arlington, Texas. I think this is the prettiest photograph that I have seen of Antheraea polyphemus.

As I’m not a biologist, I had no idea what it was, but I was quickly able to identify it as the Cyclops moth.  Indeed, several websites so identify it and note that it is named for the race of one-eyed Cyclops famously described in the Odyssey. The sites even say that Cyclops means one-eyed.

But, it doesn’t!  Besides, this moth has two eyespots.  Cyclops means “round eye”.  And this photograph shows the eyespots as very round or spherical.

Jennifer’s father, Clint, told me, “ We used to tell our baseball umpires ‘if you had another eye you’d be a cyclops ‘“.

And a pair of Great Tits from reader Pyers:

A Great Tit (Parus major) saying hello from the nest box in my garden:

And have a female Great Tit. the even more cute partner of the one I sent you the other day 🙂

Readers’ wildlife photos and videos

May 14, 2021 • 8:00 am

I am running worryingly low on readers’ photos, so PLEASE send in your good ones. I don’t want to have to cancel this feature or put it up sporadically. Thanks!

We have a potpourri of photos and movies today. Readers’ captions are indented, and you can enlarge the photos by clicking on them.

The first two photos are by Andrea Kenner.

Here’s a photo of my first sighting of a Brood X cicada. The baby is sitting on the sidewalk in Hyattsville, Maryland. I’m not sure which species he is (there are three). Here’s a link to the Wikipedia page.

I took this photo in my front yard in Prince George’s County, MD, and posted it on Facebook. The tree is an Eastern Redbud (Cercis canadensis). An entomologist in my neighborhood identified the bee as a Hairy Footed Flower Bee (Anthophora villosula), a recently introduced species in the Mid-Atlantic region.

From Linda Mercer:

It is hard to see the tiny fawn hiding behind my air conditioner.

A duck video from Brian Tarr:

I’ve been an avid lurker on your excellent website for several years, and have finally plucked up the courage to share a bit of wildlife with you. This is a sord of mallards which I filmed this last winter in Łuków, Poland, by the Southern Krzna River in the central park. I thought it a bit unusual to see so many, because I figured they would have flown south by then. As you can see, they are quite accustomed to humans, as people often come with their children to toss them bread (not the ideal diet, as I learned from you).

Please feel free to share this with your readers, if you so choose. I would love to get some feedback about migratory patterns. (Possible aberration due to climate change?)

 

And a parasitized grasshopper from Jonathan Storm:

I found this dead grasshopper on an eastern hemlock in the Blue Ridge Mountains of South Carolina. It was killed by an entomopathogenic fungus last summer or fall. These fungi are parasites that infect and eventually kill their insect host. Last summer, a fungal spore landed on this grasshopper and worked its way into the body cavity. The fungus then grew and spread until it killed the grasshopper. Several fruiting bodies of the fungus later grew out of the grasshopper and released their spores into the breeze. Some of these spores will then infect a new insect host and the cycle continues.

And a video from Jonathan:

This female Ruby-throated Hummingbird [Archilochus colubris] was collecting spider silk from a window on my house in South Carolina. The sticky and stretchy nature of the silk help hold the nest together and anchor it on top of a tree branch. Ruby-throated Hummingbirds often construct their nest from dandelion seeds, moss, and lichens and place it high up in a hardwood tree.

Readers’ wildlife photos

January 20, 2021 • 8:30 am

Tony Eales from Queensland weighs in with photos documenting a nice story of parasitism and mimicry, with the mimicry being an orchid that deceives a male wasp into trying to copulate with it. (The gain is pollination for the flower; the wasp gets nothing but frustration.)

Tony’s descriptions are indented; click on the photos to enlarge them.

I came across something quite special on the weekend. It’s a terrestrial orchid Arthrochilus prolixus, AKA Wispy Elbow Orchid.

This orchid by sight and smell imitates a wingless female Thynnid wasp. Female Thynnids often sit at the top of a blade of grass waiting for a male to find them. It is this behaviour the orchid takes advantage of.

JAC: Note how the orchid above imitates a waiting female.  The male mates with the orchid, getting pollen on its back, and then, because wasps aren’t that smart, eventually tries to mate with a different orchid, whereupon the pollen from the first orchid detaches and pollinates the second one. (Note the stamens in the orchid at lower right above.) This is known as pollination by “pseudocopulation.”

Thynnid males pick up females and carry them around while mating for many hours.

Thynnids are parasitoids of scarab beetle larvae. Scarabs live under ground or within litter for a year or more, feeding and growing. As larvae they are often known as Curl Grubs (and I realise I don’t have any photos of curl grubs which is strange, only adults). [JAC: see a photo here.]

The females deposit a single egg on any scarab larvae they find which grows and eats the larvae until emerging as an adult wasp and digging out.

Here’s a photo of a male I observed busily pulling back leaves off the ground as a newly emerged female was making her way out.

There are around 2000 species of Thynnid in Australia of which only about a quarter have been described and named. As far as I can tell no-one yet knows the species that pollinates the orchid that I found.

Here’s a good article on Australian Thynnids for the layperson.

And here is a paper describing how a different species of elbow orchid tricks the wasps into getting a wad of pollen attached to the right spot on their back with great pictures.

Recent data on how the “ant zombie” fungus works

June 2, 2020 • 9:00 am

When I first read the publicity about this recent (2017) paper in Proc. Nat. Acad. Sci., I thought that the authors had come up with a new solution to how the fungus Ophiocoryceps unilateralis, a parasite on carpenter ants, turns the ant into a zombie, behaving in a way that facilitates the dispersal of the fungus.

People are fascinated with this system because of the “zombie” connection, and because of the fact that a fungus (considered a “lower” species) can control the behavior of the ant. In this this case the fungus somehow causes the infected ant to climb onto vegetation, bite into it hard, and then die with its body extending out, allowing dispersal of the fungal spores into the air from a stalk that grows out of the ant’s corpse. The spores then disperse, and can fall on another ant so that the fungus begins it life cycle anew. Here’s the life cycle from MicrobeWiki:

And a photo of a dead and with the fungus sprouting from its body. Note how the ant has bitten into the vegetation to secure itself: a true death grip!

Source.

And here’s a Planet Earth video, with Attenborough narrating, showing the “attack of the killer fungus” Cordyceps (a different species that kills the same way) on bullet ants (a different species). But the principle is the same (though not necessarily the mechanism).

 

There are other examples of microbes or fungi controlling the behavior of their host in such a way to facilitate their own spread at the expense of the host’s life. A recently famous one involves the discovery that the protozoan parasite Toxoplasma gondii appears to change the behavior of rodents—its intermediate host—making them lose their fear of cats. The rodents are then devoured more easily by cats, who then shed the eggs in their feces, infecting more rodents who come into contact with the feces. Here’s that life cycle (it has several life stages) from Wikipedia:

Parasites manipulating the behavior of their hosts to facilitate the spread—and, of course, the spread of the genes producing that host-altering behavior—is what Richard Dawkins calls an “extended phenotype”, with the new behavior being considered a trait of the parasite that produced it. However the parasites do this, it’s a marvel of evolution—a sophisticated “behavior” of simple organisms that arose via natural selection.

Up till when this paper was published, it’s always been thought that in the case of ants and “zombie-producing” fungi, the fungus invaded the host’s brain, changing its behavior in an adaptive way for the fungus (note Attenborough’s “explanation” in the video). Now, however, the 2017 paper by Maridel Fredericksen et al. shows that the fungus invades not the brain, but muscles in every part of the body (click on screenshot below, the pdf is here, and the reference and link at the bottom). In fact, most of us missed that paper, and continued to say in the last three years that the fungus turns the ant into a zombie by invading the ant’s brain.

That excited me at first, because I thought that the fungus was somehow manipulating the actual movement of the ant’s muscles, including that crucial clamping of the mandibles on the plant. But that doesn’t seem to be the case. The invasion of muscles may provide nutrients for the parasite, but is not yet seen as a way to control the ant’s behavior. What’s new, then, is that while we still don’t know how the “zombie” behavior arises, we know it doesn’t involve fungal invasion of the brain.

The advantage of this system is that the fungus and ant can both be cultured in the lab and so experiments can be done.  The authors did sophisticated experiments involving infecting the carpenter ant Camponotus castaneus with the fungus, and also with a “control” fungus Beauveria bassiana, a general pathogen which doesn’t change ant behavior.

They infected ants with both fungi, and traced where the infection went with a combination of staining, producing serial sections of three parts of the ants’ bodies, staining the sections, training the microscope through “deep learning” AI to distinguish ant tissue from fungal tissue, and painstakingly putting together the sections.

In short, they found fungal tissue throughout the ant’s body, but not in the brain, even though the ants behaved as zombies. This shows that brain infection by fungal hyphae (the branching filaments that the fungus produces) is not responsible for changing the ant’s behavior.

What they did find is that in most ants the different fungal filaments connect up together to form a network, and that that network often encircles the ant’s muscles and sometimes invades them.  Here’s a photo showing the hyphae joining up; the caption is from the paper. “B” shows the cross section of hyphae forming connections with each other:

Fungal interactions observed in O. unilateralis s.l.-infected ant muscles. (A) Serial block-face SEM image showing fungal hyphal bodies (HB) and hyphae (arrowheads) occupying the spaces between ant mandible muscle fibers (M). Outlined boxes are shown larger in B and C. (Scale bar, 50 µm.) (B) Connections between hyphal bodies (arrows). (Scale bar, 10 µm.) (Inset) Close-up of connected hyphal bodies. (Scale bar, 1 µm.) (C) Muscle fiber invasion: hyphae have penetrated the membrane of this muscle fiber and are embedded within the muscle cell (arrows). (Scale bar, 10 µm.)

This is a cross section, but when you put lots of cross-sections together, you can reconstruct the 3-dimensional structure of the fungal network, as in this figure (again, caption from the paper)

Three-dimensional reconstructions of fungal networks surrounding muscle fibers. (A) A single fiber of an ant mandible adductor muscle (red) surrounded by 25 connected hyphal bodies (yellow). Connections between cells are visible as short tubes, and many cells have hyphae growing from their ends. Some of these hyphae have grown along and parallel to the muscle fiber (arrowhead in Inset). This reconstruction was created using Avizo software. See also Movie S1 and interactive 3D pdf (Fig. S3). (B) Two different projections of a 3D reconstruction showing several muscle fibers (blue) and fungal hyphal bodies (red) from the same area as seen in A. This reconstruction was created using a method (developed here) that uses a U-Net deep-learning model.

The fungus not only surrounded the muscles, but in some cases penetrated the muscle fibers themselves, perhaps, the authors posit, to obtain nutrients (the generalist fungus occasionally did this, too). There is no indication that this connection of the fungal hyphae with the muscles affects how the ant behaves.

So what we have is not an answer to the question of how the zombie fungus works its magic, but how it doesn’t—through the brain. But that doesn’t mean that the behavior isn’t mediated through the brain, for the fungus could still secrete some kind of molecule that interacts with the brain and doesn’t require the fungus to enter the brain. There’s still a lot left to learn. But we shouldn’t doubt that the manipulation of ant behavior really is an evolved “extended phenotype” of the fungus.

_______________

Fredericksen, M. A., Y. Zhang, M. L. Hazen, R. G. Loreto, C. A. Mangold, D. Z. Chen, and D. P. Hughes. 2017. Three-dimensional visualization and a deep-learning model reveal complex fungal parasite networks in behaviorally manipulated ants. Proceedings of the National Academy of Sciences 114:12590-12595.

Reader’s wildlife photos

May 12, 2020 • 8:00 am

Today’s photos are from regular contributor Tony Eales, who hails from Brisbane. Here we see nature red in, well, spores and mycelia—pathogenic killer fungi.  Tony’s notes are indented:

I’ve had a few interesting sightings of late and none more so than the entomopathogenic [insect and arachnid-killing] fungi I’ve found on insects and spiders.

The first two shots are of Beauveria sp. probably Beauveria bassiana commonly called Icing Sugar Fungus. In this case it has infected a Robber Fly of the genus Ommatius.

Now the interesting thing about classifying fungi is that many have a sexual form and an asexual form, and these are so different that they have been classified as separate genera in the past. So Beauveria bassiana is the anamorph (asexually reproducing form) of Cordyceps bassiana, which is known as the teleomorph or sexually reproducing form. Both together are known as the holomorph. After 1 January 2013, one fungus can only have one legitimate name. Looking at this paper, one sees that while both Beauveria and Cordyceps are legitimate genera, for this species Beauveria bassiana would be the legitimate name.

With the next one this is a species that targets spiders. The anamorphic type Gibellula is the accepted name and the former name Torrubiella for teleomorphic forms has been deprecated.

The photos are of a small spider consumed by Gibellula cf arachnophila showing the fruiting bodies. The second is of an Arkys lancearius infected with an early stage of Gibellula and after that we see the small yellow sexual form of Gibellula cf arachnophila, formerly classified as Torrubiella sp. I collected the Arkys and have it at home in test tube in the hope it will produce fruiting bodies for me to photograph.

Last, I have an unfortunate caterpillar that has been killed by Metarhizium rileyi, another entomopathogenic fungus that is being actively investigated for its ability to kill a wide range of Lepidopteran pests. While there’s always been interest in using entomopathogenic fungi like B. bassiana and M. rileyi, the virulence of entomopathogenic fungi is affected by environmental factors such as temperature, humidity, light, and solar radiation.

The astounding way a fungus controls the behavior of “zombie ants”

November 10, 2017 • 11:00 am

You’ve probably heard about “zombie ants”: ants that become zombie-like when infected by a certain parasitic fungus. Like many parasites, some fungi can control the behavior of their hosts, and they do this to increase their own fitness, affecting the host’s morphology and behavior to make it more likely that the parasite will pass its genes to the next generation. This is simple natural selection operating on the parasite, but doing so in a way that captivates and fascinates both biologists and laypeople. How can a fungus or worm take over a larger animal and make it do its “will”? (I’m speaking in biological shorthand here.)

One of the iconic examples of such parasitism involves those zombie ants. When a carpenter ant is infected by the parasitic fungus Ophiocoryceps unilateralis (henceforth, “the parasite”), the ant’s behavior eventually changes. The parasite enters the ant through the cuticle, and then begins to grow. After 16-25 days, the fungus makes the ant climb a plant (they nest in the ground), move to a conspicuous location on a plant, and then bite down hard on a plant vein, affixing itself firmly to the vegetation. The ant dies, and the fungus grows a stalk out of the ant, ready to disperse its spores to the ground, where the infection and life cycle will resume when the fungus is encountered by the next unlucky ant.

Here’s what the dead ants with the parasite growing out of them look like:

From Wikipedia: “Ants biting the underside of leaves as a result of infection by O. unilateralis. The top panel shows the whole leaf with the dense surrounding vegetation in the background and the lower panel shows a close up view of dead ant attached to a leaf vein. The stroma of the fungus emerges from the back of the ant’s head and the perithecia, from which spores are produced, grows from one side of this stroma, hence the species epithet. . . Fungus species: Ophiocordyceps unilateralis Ant species: Camponotus leonardi doi:10.1371/journal.pone.0004835.g001

Another photo:

A dead carpenter ant with fungal spores erupting out of its head. (Image: David Hughes/Penn State University) From Gizmodo.

Clearly, the fungus is somehow manipulating the ant’s behavior to facilitate reproduction of the parasite. But how does it do this?

We don’t know exactly in any case (though there are a fair number of cases), but it must involve either growth of the parasite inside the host or chemical manipulation of a host(or both)—presumably in ways that affect the host’s brain. After all, if the brain isn’t affected, how can you modify the host’s behavior?

We now have a better, but still incomplete, idea of what’s going on with zombie ants from work described in a new paper in PNAS by Maridel Fredericksen et al.  (reference at bottom and free access; pdf here). What the authors did was infect carpenter ants (Camponotus castaneus) in the laboratory with the “zombie-making” O. unilateralis fungus (as well as with a control fungus that doesn’t create zombie ants but does kill them). Then right when at the crucial moment when ant bites down on the plant, they microdissect that infected ant to see where the fungus was.

This latter procedure was a tour de force, for it involved a complex series of manipulations on a very tiny creature. The ant was dissected tiny bit by tiny bit, and then each bit was treated with immunofluorescent stain that could distinguish between fungus tissue and ant tissue. The authors then developed a computer program to look at the microscopic sections and put them together. This procedure, called “deep learning”, is a huge improvement over it being done by hand—the usual technique. As Gizmodo notes:

Using electron microscopes, the researchers created 3D visualizations to determine location, abundance, and activity of the fungi inside the bodies of the ants. Slices of tissue were taken at a resolution of 50 nanometers, which were captured using a machine that could repeat the slicing and imaging process at a rate of 2,000 times over a 24-hour period. To parse this hideous amount of data, the researchers turned to artificial intelligence, whereby a machine-learning algorithm was taught to differentiate between fungal and ant cells. This allowed the researchers to determine how much of the insect was still ant, and how much of it was converted into the externalized fungus.

What they found was surprising:

1.) First, there was no fungus in the ant’s brain, though it was present throughout the body. This really was a surprise, as everyone expected that the fungus would glom onto the ant’s brain, and that was the way it controlled its behavior. Instead, there was fungus everywhere else in the ant, especially in the muscles. (That was true of the “control” fungus, too, but, surprisingly, the paper gives no information about whether the control fungus was found in the ant’s brain).

Here’s part of a figure showing the ant’s brain (stained in green), and the nearby fungus (red); scale bar is 20 microns. There are a few fungal tracheae in the brain (arrowheads) but nowhere near the degree of intermixing of brain and fungus cells seen in muscles, and there are no fungal hyphae (the filaments of the fungus that conduct and transfer nutrients) in the brain at all, whereas they’re deep into the muscle (see below).

2.) The fungus formed a connecting network of hyphae that attached to and penetrated the ant’s muscles. Here’s an example of the networks of fungi (yellow) surrounding the ant’s muscles (red) from the paper:

(From paper): Three-dimensional reconstructions of fungal networks surrounding muscle fibers. (A) A single fiber of an ant mandible adductor muscle (red) surrounded by 25 connected hyphal bodies (yellow). Connections between cells are visible as short tubes, and many cells have hyphae growing from their ends. Some of these hyphae have grown along and parallel to the muscle fiber (arrowhead in Inset). This reconstruction was created using Avizo software.

What is the fungus doing infiltrating the muscle and forming a network that ramifies widely throughout the ant’s body? The authors posit, and this seems likely, that the fungal hyphae are sucking nutrients from the ant’s muscles and transferring them to other fungal cells not touching the muscles. This may be how the fungus feeds itself and grows throughout the ant. Muscles are rich in mitochondria, which give the ant energy reserves and are good food for the fungus. The authors also observed severe atrophy of the muscle probably connected with the fungal invasion. This muscle infiltration and formation of networks was not seen in the control fungus.

So we have two questions left:

Why does the fungus not infiltrate the brain?  We don’t know, but it’s possible that doing that would quickly kill the ant and render it useless for further growth and manipulation of behavior. Further (or in addition), it may be easier to control the ant’s behavior by secreting chemicals into an intact brain than by brute-force physical invasion of the brain. After all, the behavioral manipulation by the fungus is precise: it makes the ant go to a specific exposed position on the plant (see below) and then bite down hard with its mandibles.

So how is the fungus affecting the ant’s behavior? We still don’t know. Clearly the fungal attachment to the muscles is not somehow moving the muscles in a preferred way or controlling the mandibles; rather, the muscle infiltration is a way for the fungus to get the energy it needs to grow and then form the stalk that spreads spores. What is very likely, but remains to be shown, is that the fungus secretes a chemical that somehow affects the intact brain in a way that makes the ant behave like a zombie. The authors do note that metabolite chemicals secreted by the fungus differ when it is near the brain than when it is near the muscle. Not only that, but the behavioral modification is more than just biting: the ant goes to a very specific place before biting, and that directionality somehow has to be produced by the parasite as well. As Wikipedia notes,

An infected ant exhibits irregularly timed full body convulsions that dislodge it to the forest floor. The ant climbs up the stem of a plant and uses its mandibles with abnormal force to secure itself to a leaf vein, leaving dumbbell-shaped marks on it. The ants generally clamp to a leaf’s vein at a mean height of 25.20 ± 2.46 cm above the forest floor, on the northern side of the plant, in an environment with 94–95% humidity and temperatures between 20 and 30 °C (68 and 86 °F). Infections may lead to 20 to 30 dead ants per square meter. “Each time, they are on leaves that are a particular height off the ground and they have bitten into the main vein [of a leaf] before dying.” When the dead ants are moved to other places and positions, further vegetative growth and sporulation either fails to occur or results in undersized and abnormal reproductive structures.]

In other words, the fungus has to direct the dying ant to a specific microenvironment optimal for survival and propagation of the spores.

This adds up to a real tour de force of natural selection: imagine the evolution of a chemical that can make the ant behave in such specific ways! The mind boggles: what were the intermediate steps in the evolution of this kind of host manipulation?

As Matthew emailed me (he found the paper), “What an amazing adaptation of the fungus to make the ant do the things the fungus needs it to do (‘puppet master’ is wrong metaphor because the fungus isn’t the master—natural selection is!)”.  It’s stuff like this that keeps the evolutionary biologist—well, at least the ones with imagination—in a constant state of wonder and awe.

Now of course we don’t know the crucial answer: how does the manipulation of behavior actually work. But we know at least that it’s probably chemical rather than physical, and we also know that the parasitic fungus evolved adaptations for sucking nutrients from the ant’s muscles. That’s two steps forward. And the usual ending of scientific papers applies: “More work needs to be done.”

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M. A. Fredericksen et al. 2017. Three-dimensional visualization and a deep-learning model reveal complex fungal parasite networks in behaviorally manipulated ants. Proc. Nat. Acad. Sci USA.published ahead of print November 7, 2017doi:10.1073/pnas.1711673114

Poor Nemo!

February 15, 2017 • 10:00 am

by Matthew Cobb

Here’s a gorgeous photo of clownfish, which just won the photographer, Qin Ling of Canada, an award in the Behaviour category at the Underwater Photographer of the Year competition (click to enlarge) – you can see all the winners here.

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Ling’s photo is entitled ‘Your home and my home’. Look closely at these Nemos. Look at their mouths. Those little eyes peeking out. They are not drawn on, as PCC(E) first suggested, nor are they Photoshopped. And they are not babies. They are isopods (like pillbugs or woodlice), which are parasitic. They eat the fish’s tongue, and then replace it, sitting in there, presumably getting first dibs on the food as it comes in. They occasionally turn up on people’s dinner plates when folk order fish and get a crustacean chaser.

The photography judge said:  “Six eyes all in pin-sharp focus, looking into the lens of the author … this was one of my favourite shots of the entire competition.”

Isn’t nature wonderful?

*********

JAC: Let me add two references and two videos.  You can read Carl Zimmer’s take on these parasites at National Geographic, or Wikipedia’s entry on Cymothoa exigua, the “tongue-eating louse,” which appears to be the only species that does this.

Here’s a video, which has only one photograph:

Here’s another video with photos; it claims that this is the only case in which one organism replaces another organism’s body part: