You are currently browsing the tag archive for the ‘parasitoid’ tag.

Q0W0R090DQ7QNRJKURZQWRKQFRXQBR3KWR80TQ70H0KQTR20K0N0R0P0Z07QCRE000203RKQJR2000U0Q0KQZ060S040

This summer I have spent a great deal of time in the garden which has been my refuge from the plague, turmoil, and strife.  I keep hoping that the carpenter bees will return, but I have barely seen any hymenopterans at all thus far (aside from little black and brown ants which seem to be as numerous as ever).  That all changed the other day, though, when a magnificent visitor swept into the garden!  A lot of hymenoptera are strikingly colored (as the velvet ants will testify) , however this dapper character looked like a refugee from a 1980s musical video or a disturbing anime.  Not only was this wasp’s jet fighter body the deepest brown (which was so dark it might have been black), but all four of its wings were the same color too! Not only was the whole creature sable, but its dark brown coloring was also iridescent blue/purple–so it gleamed like a blue revolver.  There was one noteworthy contrasting color on the wasp’s face– its huge antennae were fluorescent orange!

6Z0L5ZQLNZ5HFH2HAHXHOHGHRR6HBHQLVZGLYH7LGZ7HGZ0LTHWHOHLLAHKL6ZLLOH7H2ZMH4Z8HTHQL1HPHVH4HAH

Although the wasp seemed like it was preening on my hostas, as soon as I moved to get my camera it was gone.  So, alas, I have no photos of the strange visitor.  Fortunately though, this wasp was more visually unique than a Dick Tracy villain so I quickly found a match in the rogue’s gallery of wasps online: Gnamptopelta obsidianator, the “bent-shield beseiger wasp”

Now you would think that if crazy creatures like this were flying all over New York City, there would be plenty of information about them online, but you would be wrong.  It speaks of our human myopia that, although I easily found pictures of it, I could barely find out anything about the lifestyle of the beseiger (although one website opined that I had actually seen the lookalike wasp Thyreodon atricolor–so keep that in mind, for what it is worth). According to the internet, these wasps are both ichneumonids– parasitoid predators which lays eggs inside living hosts.  Paralyzed, the hosts still-living flesh provides a decay-resistant larger for the wasp larvae [shudders].

5KTKXKDKHKHS8QD06QRSBQLSWQ10RKC02QC0GQ9KKKTKWQLSNQHSUQDK4KHS9QTK1QCK5K1KZK9KSK9KGKOK8KHS4K

Whatever you might think about the terrible things this wasp does to make ends meet, there is no denying that it belongs here just for its sheer fashion sensibility alone.  I will keep my eyes peeled for more of these magnificent yet troubling wasps–both in the garden and online.  I still can’t believe we know so little about creatures which literally live right next to us!

Maculinea arion

Hey, look at that!  It’s a delicate pale blue butterfly (Maculinea arion) from Europe and northern Asia. What could this ethereal creature have to do with the horror theme which this blog has been following as a lead-up to Halloween?  In fact, what does the butterfly have to do with any of Ferrebeekeeper’s regular themes?  Butterflies are lepidopterans rather than the hymenoptera we favor here.

As it turns out—the butterfly has a lot to do with hymenopterans.  Maculinea arion, or “the large blue butterfly ” to use its not-very-creative English name, may look innocent as a butterfly, but in its larval stage the creature is both appalling and remarkable.   Alcon caterpillars are myrmecophiles—which means the caterpillars live in association with ants.  Despite the Greek meaning of ”myrmecophile”  (to love ants) the relationship is anything but loving on the part of the Alcon caterpillar–unless love is meant in the same way as “to love ham”.

Maculinea arion (Large Blue) larva carried by ant (Drawing by Frohawk)

M. arion caterpillars are relentless predators of ant larvae.  The way they obtain this fragile foodstuff is remarkable for sophistication and ruthless guile.  When a caterpillar hatches, it lives for a few days on wild thyme or marjoram plants.  The caterpillar then secretes a sweet substance which attracts red ants which carry the larva back to their tunnels.

Inside the ant hive, the caterpillar produces pheromones and chemical scents which mimic those of the ant queen.  It also scrapes a small ridge on its first segment to produce the same noise as the ant queen. The ants are deceived by the caterpillar’s mimicry and they take it to the chamber where they rear their own larvae.  The ants wait on the caterpillar as though it were the hive monarch and they even feed it ant larvae—their own undeveloped siblings.  Once it pupates, the butterfly scrapes the inside of its chrysalis to continue the deception.  When the butterfly emerges from its cocoon the hapless ants carry it outside and guard it as its wings harden—whereupon the butterfly departs to mate and lay eggs on wild thyme or marjoram plants.

Phengaris alcon

The Maculinea Arion is not the only caterpillar to make use of this strategy.   The Phengaris alcon butterfly acts in almost exactly the same way.  Here is where the story becomes impressively crazy.   A parasitoid wasp, Ichneumon eumerus, feeds on the alcon caterpillar inside the ant hive.  The wasp infiltrates the hive by spraying a pheromone which causes the ants to attack each other.  While they are busy fighting, the wasp lays its eggs inside the caterpillar.  The wasp larvae hatch into the body of the caterpillar (which the ants think of as a queen) and they eat the caterpillar host safe in the cloak of this deception.

The parasitic wasp Ichneumon eumerus. (Image: J.Thomas/Natural Visions)

If an ant hive becomes too saturated with caterpillars it will die and all three species inside the hive will likewise perish).   The red ants in this scenario are constantly evolving new pheromone signals to outcompete the caterpillars and wasps—which in turn coevolve with the ants.  It’s strange to imagine the troubling world of deception, chemical warfare, and carnage just beneath the ground.

Have you ever watched a tiny red ant scurrying through the backyard only to be astounded that the ant seems like a giant when it walks by some much smaller black ants?  Such observations have always caused me to wonder how small insects could become.  What are the smallest insects out there and just how tiny are they?   The answer is actually astonishing, and, like most good answers it just brings up more questions.  Most entomologists believe the tiniest living insects are the fairyflies, infinitesimally minute parasitoid wasps which live on or inside the tiny eggs of thrips(well, some fairflies also live inside the brains of other insects, but let’s not think about that right now).  Fairyflies are smaller than many single cell organisms like paramecia, amoebas, and euglenas.    Dicopomorpha echmepterygis,  a wasp from Costa Rica, is an astonishing  .13 millimeters in length.   Although many of these wasps fly, they are so tiny that they don’t have conventional wings:  some of the smaller specimens have long cilia-like hairs which they use to row through the air (the fluid dynamics of which are considerably different for creatures so small).

Fairy wasp with single celled organisms under electron microscope

In fact the wasps are so tiny that the millions of individual cells which make up their tissues and organs have to be very miniscule indeed.  In fact, according to physics, the brains of fairyflies should not work.  Many of the neural axons are smaller than 0.1 micrometre in diameter (and the smallest axons were a mere 0.045 μm).  At such sizes, the electrical action of axons should not work properly.   An article on Newscientist describes the basic problem:

 …according to calculations by Simon Laughlin of the University of Cambridge and colleagues, axons thinner than 0.1 μm simply shouldn’t work. Axons carry messages in waves of electrical activity called action potentials, which are generated when a chemical signal causes a large number of channels in a cell’s outer membrane to open and allow positively charged ions into the axon. At any given moment some of those channels may open spontaneously, but the number involved isn’t enough to accidentally trigger an action potential, says Laughlin – unless the axon is very thin.

So how do the wasps continue to fly around and parasitize the eggs of other creatures if the electrical impulses of their brains do not work?  German researchers speculate that the axons of wasp brains work mechanically rather than electrically.  The tiny axons touch each other physically instead of by means of electrical action.  If this is correct it means the wasps are analogue creatures with little clockwork minds!  If they were any larger or more complex, this would not work, but because of their small size and simple drives, they can manage to operate with slow-moving machine-like brains.

Micrograph of a fairyfly (fairy wasp)

A “Zombee” tattoo (by Josh Herrera of Skin Factory in Las Vegas)

More bad news for honeybees: not only do our hard-working black-and-yellow friends have to contend with blood sucking varroa mites, neonicotinoid insecticides, and giant hungry bears, but a new plague has been spreading from the west coast, claiming the life of domestic honey bees.  The Zombie fly (Apocephalus borealis) is a disgusting little hunchbacked phorid fly which has traditionally preyed on native wasps and bumblebees.  Phorid flies, coincidentally, are a successful family of over 400 species of tiny flies which tend to run very rapidly (although they are capable of flight).  The most famous phorid fly (insomuch as that’s a thing) is probably the coffin fly—although the zombie fly is working its way into the limelight too.  Charming!

The parasitic fly Apocephalus borealis on the back of a bumble bee (photo by Kimberly G. O’Harrow)

Like the horrifying parasitoid wasps, the zombie fly uses its syringe-like ovipositor to inject its eggs inside of its victims.  As the larvae hatch they attack the bee’s brain and cause it to behave in bizarre manners—such as lurching around in a random fashion or flying at night (which gets the bee away from the hive and ensures that the fly lavae are not destroyed by the bee’s concerned colleagues).  Bees so affected are mordantly known as “zombees” for obvious reasons.  Eventually the zombie fly larvae pupate into hard little cocoons which resemble grains of rice.  When they hatch they rip through the bee’s body at the juncture of the head and thorax, frequently decapitating the bee.  Sometimes it is difficult to enjoy the beauty of nature.

Adult female Apocephalus borealis fly (image from Core A, Runckel C, Ivers J, Quock C, Siapno T, et al. (2012). “A new threat to honey bees, the parasitic phorid fly Apocephalus borealis”. PLoS ONE 7 (1))

It is unclear to what extent zombie flies are contributing to the decline of honeybees at large–since the flies have not traditionally attacked domestic bees.  Perhaps the death and decline of other native bees has pushed the zombie flies into this new behavior (or maybe they were getting around to it anyway—they sound like thoroughly repulsive customers).  At any rate, beekeepers have a new problem to worry about, and are tracking confirmed instances of “zombees” online at www.zombeewatch.org.

The Sole Extant Specimen of the parasitoid wasp Aleiodes gaga

Voila, allow me to present Aleiodes gaga, a parasitoid wasp, which along with 178 other species, was discovered in the cloud rain forests of Thailand as part of a new biological survey seeking new life forms.  The drab little 5mm wasp is named after the flamboyant New York singer songwriter Stefani Joanne Angelina Germanotta (who rose to international superstardome under the stage name of “Lady Gaga”.  The science/futurist website i09 somewhat cynically remarks, “As to why the researchers chose to “honor” Lady Gaga in this way is not entirely clear (they’re likely seeking attention — in which case the name is wholly appropriate).”

Lady Gaga

The remarkable aspect of the survey is that the new species were swiftly identified and categorized by DNA barcode rather than through traditional taxonomic means.  The team used a fragment of mitochondrial DNA to identify the various invertebrates which it discovered.  However, the new methodology has critics in the world of scholarly taxonomy, who lament that spotting arbitrary genetic differences is replacement for actually understanding a creature’s morphology, anatomy.

Scientists do not know about the habits of the gaga wasp, but they know that it is a parasitoid wasp, a class of hymenopterans which provide a useful biological check against various diseases, blights, and swarms.  When malicious insects attack certain plants, the plants release specific chemicals which attract particular species of wasps (which then prey on the offending beetle, ant, larva, or whatever).  A great many species of plants have particular wasps affiliated with them (since the wasp and the plant coevolved to meet each other’s needs).  Although such wasps provide an incalculable boon for both domestic and wild plants of all sorts, they are also the fodder for horrified screaming (since they tend to use mind control to render victims into zombies, which the wasp larvae then devour from within).

A Parasitoid Wasp injecting eggs into a paralyzed Hoverfly Larva

Most likely the wasp finds some local caterpillar, paralyzes it with a sting to the head, and lays its eggs inside the hapless victim.  When the wasp larvae awake they devour the still living caterpillar.  So to recap, this wasp 1) was discovered by means of a controversial technique; 2) was named in a naked bid for publicity; and 3) lays eggs inside its prey’s head which subsequently cause aforementioned head to explode.

Lady Gaga wearing a red gothic crown and…um…a damask table cloth I guess.

A female velvet ant (mutillidae wasp)

Velvet ants (Mutillidae) are not actually ants at all—the insects are classified as wasps even though female velvet ants do not have wings and appear to be tiny furry colorful ants. The Mutillidae family of wasps—which is made up of more than 3000 species– illustrates how closely wasps, bees, and ants are actually related.   Male velvet ants look nothing like the females but are much larger winged creatures resembling other wasps.  So great is the sexual dimorphism between the genders that it took entomologists a tremendously long time to pair the females with the males, and in many species the connection has still not been made by science.  The genders do however both share a ridged structure called a stridulitrum, which can be rubbed or struck to produce chirps and squeaks for communication.

Male velvet ant (mutillidae wasp)

Female velvet ants are notable not just for their colorful fur but for their tremendously powerful sting which is so painful that they are nicknamed “cow killers.”  Male velvet ants look like wasps but do not sting.  The exoskeletons of velvet ants are tremendously hard to such an extent that some entomologists have reportedly found it difficult to drive pins through specimens.  The dense hard coating helps the females invade the underground burrows of larger bees and wasps which the velvet ants sting and lay eggs on.  When the velvet ant larvae hatch they feed on the paralyzed victims before metamorphosing into adult form and venturing into the world.

Blue velvet ant (female)

Velvet ants are found in warmer parts of the world particularly deserts.  The majority of species are red and black but a variety of other colors are known including blue, gold, orange, and white.  Unlike the social ants and termites, velvet ants are generally solitary, coming together only to reproduce with their strangely alien mates.

Copidomopsis floridanum injecting its eggs into a caterpillar.

Sometimes horror is a matter of perspective.  For example, parasitoid wasps–some of the most horrifying hymenoptera–are also some of the most beneficial to humankind. The parasitoid wasps are a hugely diverse superfamily among the hymenoptera consisting of more than 6000 different species.  These insects are ancient, successful, and profoundly useful for controlling invasive species or pests (particularly various arthropods), however as soon as one knows what “parasitoid” means it becomes difficult to regard these wasps without revulsion and distaste. A parasitoid is a creature which lives inside another creature (the host) and ultimately kills/destroys that host by consuming it or by bursting out of it.  The detailed dynamics of this relationship are often grisly in the extreme, but they highlight the bizarre (not to say disturbing) mutualism which is such a feature of the natural world.

The emerald cockroach wasp or jewel wasp (Ampulex compressa)

Parasitoid wasps are especially alarming because of the extent to which they can manipulate the behavior of their host.  For example the emerald cockroach wasp (Ampulex compressa) is a solitary hunting wasp which finds a single cockroach and delivers a mildly paralytic sting to the roach’s thorax.  This first sting temporarily incapacitates the roach and allows the wasp to carefully make a second more meaningful sting to a precise spot in the roach’s brain which control’s the roach’s escape response. Not only does the wasp know where to sting, she utilizes a toxin which specifically blocks receptors for the neurotransmitter octopamine. The wasp then chews off a portion of the roach’s antennae and returns to her layer leading the captive roach by holding its damaged antenna like a leash. Inside the wasp’s burrow she plants a single egg on the roach’s belly and then seals the zombified insect inside the chamber with sand and pebbles.  After three days the wasp’s egg hatches and the new larva feeds for 4–5 days on the external portions of the roach.  It then burrow inside the still living roach and devours the creature’s organs in a progression which leaves the roach alive for a maximum length of time.  When the roach is near death the wasp larva builds a cocoon inside it, metamorphoses into an adult, and then bursts out of the roach carcass and flies off.

Aaaagh!

Across the many different parasitoid wasps there are many variations of this behavior involving different arthropod hosts–and specifically targeting the host’s eggs, lava, or adult form.  Additionally there are sundry vectors by which the parasitoid wasps control their hosts.  Not all wasps utilize targeted neuropoisons like the emerald cockroach wasp.  Wikipedia elaborates on how close the biochemical relationship between the parasitoid wasps and their hosts can become:

Endoparasitoid species often display elaborate physiological adaptations to enhance larval survival within the host, such as the co-option of endosymbiotic viruses for compromising host immune defenses. These polydnaviruses are often used by the wasps instead of a venom cocktail. The DNA of the wasp actually contains portions that are the templates for the components of the viral particles and they are assembled in an organ in the female’s abdomen known as the calyx.

In other words some wasps utilize ancient hunks of rogue DNA to directly or indirectly control (and then destroy) their host organisms.

Braconid wasp lavae (Cotesia congregatus) destroying a tomato hornworm

The biochemical sophistication of the parasitoid wasps does not end there.  Certain wasps seem to have a symbiotic relationship with plants.  When these plants are gnawed by harmful insects (especially beetles or caterpillars) the plants release specific chemicals which summon the parasitoid wasps, which, in turn, destroy the insects. An example of this can be found in that most ubiquitous of American staple crops, corn.  When beet armyworm caterpillars  (Spodoptera exigua) start eating a live corn plant, it releases a chemical which attracts  parasitiod wasps of the species Cotesia marginiventris (the larvae of which utilize beet armyworm caterpillars as hosts). If however the corn is invaded by corn earworns (Helicoverpa zea) it will release a different chemical which attracts a different   wasp Microplitis croceipes.  As scientists look further into such relationships, they are discovering that most plants have a vast range of chemical tags which are appealing to specialized parasitoid wasps (and to sawflies).  Perhaps one of the reasons that various blights have been able to make such deep incursions in new ecosystems is the absence of plants’ terrifying little friends.

Cotesia marginiventris on a corn leaf

Ye Olde Ferrebeekeeper Archives

August 2020
M T W T F S S
 12
3456789
10111213141516
17181920212223
24252627282930
31