August 14 - Fahrenholzia pinnata

Fahrenholzia pinnata is a species of louse that is found sucking blood on kangaroo or jumping mice in the western U.S. The name of this genus is in honor of Heinrich Fahrenholz, who was a German entomologist who studied lice. The pattern that the evolutionary trees of parasites tend to mirror those of their hosts is now called "Fahrenholz's Rule" (though was coined by Eichler, not by Fahrenholz himself). And, lice are almost always the textbook example of this rule. This is because lice spend almost their whole lives on their hosts and become adapted to clinging to their hair to avoid being groomed away. The only time they have an opportunity to transfer from one host to another is via direct contact - which, if you're a rodent, is likely to only occur between members of the same species. This phenomenon is especially true in gophers. See the post from July 16 for more information on gopher lice.

August 5 - Dinemoleus indeprensus

Dinemoleus indeprensus is a parasitic copepod which is in the same family as Pandarus rhincodonicus (the whale shark ectoparasite), however there is something that sets this little guy apart from the rest. For obvious reasons, parasite fauna are usually described only after their host species are recognised - but not this one. D. indeprensus is an ectoparasite of the Megamouth Shark (Megachasma pelagios), and it is notable for being probably the only parasite to have been formally described before its host. Due to some unusual reasons, while D. indeprensus was already described in 1978, the Megamouth itself was not officially described until five years later in 1983!

The description for D. indeprensus is here:
Cressey, R., Boyle, H. (1978) A new genus and species of parasitic copepod (Pandaridae) from a unique new shark. Pacific Science 32:25-30, which is also where the picture came from - check out the intro of that paper!

Contributed by Tommy Leung.

August 2 - Gnathia trimaculata

TThe parasite for today is a parasitic isopod belonging to the family Gnathiidae - the larvae of this particular species feed upon the requiem shark (Carcharinus melanopterus). There are many different species of gnathiids parasitising many different species of fish, and they have an interesting life-cycle which involve "protelian parasitism" where only the juvenile stages (called a praniza) are parasitic, while the adult stages are free-living. They go through several stages of development, alternating between feeding and non-feeding developing stages (when they are engorged with blood) before reaching sexual maturity.

They are almost like a functional equivalent of ticks for fishes - they wait in ambush for a passing host, and when one arrives, it climbs onboard, sucks blood for a few days until full, then drops off to develop into the next stage. And like ticks, they can also act as vectors which can transmit blood parasites between the fishes they feed upon.

The photo shows a pair of third-stage pranizae, scale bar is 1 mm and it came from this paper:

Coetzee, M.L., Smit, N.J., Grutter, A.S., Davies, A.J. (2009) Gnathia trimaculata n. sp. (Crustacea: Isopoda: Gnathiidae), an ectoparasite found parasitising requiem sharks from off Lizard Island, Great Barrier Reef, Australia. Systematic Parasitology 79:97-112


Contributed by Tommy Leung.

July 29 - Haematopinus quadripertusus

Haematopinus quadripertusus, commonly called the cattle tail louse, get its name because, well, because it lives on the tails of cattle. These lice will actually take their blood meals from both ends of the cow, however, and can also be found on the mouth and in the ears as well as some of the soft bits on the backside. This louse was introduced into the Southern U.S. and is now a major pest of cattle in Florida, where they can cause anemia and weight loss - not something you want if you're trying to fatten up your cattle. Lice can spread from cow to cow when they are in close contact or via rubbing on the same thing such as a post. But, the lice can also colonize completely different herds of cattle by hitching rides on flies!

Image from this site, which has additional information on these parasites.

July 16 - Geomydoecus coronadoi

Pocket gophers are fossorial rodents belonging to the family Geomyidae. These New World rodents build complicated underground burrow systems, producing multiple mounds of excavated soil at the surface, and often wreaking havoc to agricultural crops and pastures. Pocket gopher individuals live in small, isolated populations generally living solitary lifestyles, with one gopher occupying a burrow system. All pocket gophers have external fur-lined cheek pouches that they use to carry food (hence the name “pocket”). Another thing that pocket gophers have in common is that they are parasitized by chewing lice (Phthiraptera: Ischnocera). Chewing lice are wingless insects and obligate and permanent ectoparasites; they cannot survive for long periods of time off their hosts. There are approximately 122 species and subspecies of these ectoparasitic chewing lice (belonging to the genera Geomydoecus and/or Thomomydoecus) and given the solitary lifestyle of their hosts in conjunction with their own limited dispersal abilities, gopher chewing lice are highly host specific. The close association between these wingless ectoparasites and their hosts has enabled the gopher-louse system to become a model system for studies of cospeciation. The pocket-gopher louse assemblage has been examined for almost 30 years using various types of data including distributional information, hosts associations, allozymes, and DNA sequences. Repeated statistical comparisons have shown that pocket gophers and their lice have been cospeciating over evolutionary time with lice often showing increased evolutionary rates. Current research includes additional examination of cospeciation at various taxonomic levels, and studies of parasite ecology, parasite transmission, and coadaptation enabling the gopher-louse assemblage to continues to be a model system in evolutionary biology. The species shown here is Geomydoecus coronadoi.

Post and photo contributed by Jessica Light.

June 20 - Gyrodactylus turnbulli

Ever wondered what attracted your mom to dear ol' dad? Well, if you mom was a guppy (Poecilia reticulata), it might very well have been his bright flashy colors. Turns out that female guppies can use the brightness of a male's spots to assess whether or not he is infected with a parasite, such as Gyrodactylus turnbulli, a common monogenean trematode. Classic work by Anne Houde and others showed that infected male guppies showed less intense orange spots and that female guppies preferred them less in mate-choice experiments. They may be using these cues as a means of avoiding being parasitized themselves, but they are also probably trying to pick males with good genes so that their offspring might be resistant to parasites, too.

Photo by Marilyn Scott and comes from this website.

June 6 - Dermanyssus gallinae

Dermanyssus gallinae, or the red mite, is an ectoparasite of birds. They do not live on birds, but rather hop on them to feed on their blood at night, while they are sleeping. They can be major pests for chicken and other poultry farmers. They will occasionally take blood meals from mammals, even humans, if they work with or live near birds.

May 28 - Eutrombicula alfreddugesi

If you’ve ever had chiggers, you know they’re really, really irritating. These are the parasitic larval stages of free-living mites, and Eutrombicula (Trombicula) alfreddugesi is the most familiar in North America. Chiggers perch on foliage, climb aboard passing pedestrians, and find their way to the new host’s skin. Once there, the tiny mite positions itself atop a hair follicle or pore, and secretes highly digestive saliva that liquefies the host’s skin cells. The surrounding cells harden in defense, forming a stylostome. But it’s a poor defense – the stylostome helps the parasite by functioning as a straw for the chigger to slurp his slurry of dead cells. Moreover, the stylostome contributes to that really, really irritating inflammatory (i.e., itchy) response in the host’s skin. Thankfully, E. alfreddugesi is not a vector for disease, and the discomfort subsides after a few days.

Eutrombicula alfreddugesi isn’t picky, and infects numerable hosts besides humans. It’s a parasite of many vertebrates, including birds, mammals, and reptiles (the photo shows several chiggers on the dewlap, or throat fan, of an anole lizard). In fact, host habitat is probably more important that host taxonomy for this species. Chigger infestations usually occur in warm, shady, and moist environments, as this is best for the soil-dwelling and detritus-eating adult stages (meaning that this is where most eggs are laid). Similarly, these chiggers prefer certain areas on the host, from the undergarment areas of humans, to the “mite pockets” of some lizards. Mite pockets are small, but relatively deep, cavitations that are typically located just behind the lizard’s forelimbs. When these lizards have mites, most are in the pockets, leading some scientists to speculate (and others to dispute) that a pocketful of mites is advantageous for the lizard. The chiggers are bright red, and on a drab lizard, they present a flashy spot of color that can be turned on and off as the lizard moves its legs.

Contributed by Bryan Falk.

April 28 - Melophagus ovinus

What do you call a fly that doesn't fly? In this case, you call it a sheep ked. Melophagus ovinus is a very common ectoparasite of sheep. The adults feed off the blood of the sheep, hiding easily in the wool. The females will give "birth" to well-developed larvae, which actually feed off "milk" that is secreted by specialized glands of their mother. They then pupate, cementing the pupal case to the wool. The pupal stage will last for about a month and this stage is unfortunately resistant to any insecticides, making keds difficult to eradicate if the population is firmly established. Keds are distressing to the sheep and as they attempt to itch them, they will rub off or thin out their wool. thus pose economic threats to shepherds who find themselves struck with these pesky insects.

April 21 - Cyamus ovalis

Some of you might be familiar with the New Zealand movie "Whale Rider" - well, the parasite featured today is a real whale rider.

Cyamus ovalis belongs to a family of crustaceans call Cyamidae that specialize as ectoparasites of cetaceans. Despite being called "lice", whale lice are actually amphipods, and unlike most amphipods (such as sand hoppers or "scuds") which have bodies that are laterally flattened (narrower when viewed from top), the whale lice have dorsally flattened bodies, like a crab, better suited to the life-style of clinging onto the surface of an oceanic behemoth. Because of their lack of free-swimming stages, whale lice can only be transferred from whale to whale on contact. As a result, they have a very close co-evolutionary relationship with their host, and different species of cetaceans have different species of whale lice

Whale lice have been used to track the population genetic structure of their whale hosts. In the case of Cyamus ovalis, their hosts are the right whales Eubalaena spp. Swarms of C. ovalis cover the raised pieces of roughened skin (call callosities) on the head of the whale. Studies into their population genetic structure have revealed that, just like their whale hosts, the Northern and Southern Hemisphere populations of lice have been isolated from each other for several million years.

For more information, on the coevolution of whale lice with their host, see this link . The photograph for Cyamus ovalis was taken from the same webpage as the one above - Photo Credit: Vicky Rowntree, University of Utah.

There is also a trailer on YouTube for an upcoming documentary about researching whale lice. If this doesn't make being a parasitologist look like the most exciting career out there, what will?

Thanks to Tommy Leung for all of this.

April 18 - Demodex folliculorum

One of the things that grosses non-parasitologists out (and probably many parasitologists!) is the fact that little tiny mites live on our eyelashes. These are Demodex folliculorum, and they can actually inhabit many different follicles on humans' faces. In fact, they're a bit social - as many as 10 of them can co-exist in a single follicle (party on the forehead - spread the word!) There are no known pathogens that they spread, but they can cause people to lose hair and they can make pores larger. They don't bite people and instead they mostly just munch up the secretions from our sebaceous glands. One of the coolest things is that they seem to be so incredibly efficient at digestion that they don't produce waste - so much so that they don't even have an excretory pore for defecation. So, if you have to deal with the fact that right now there are potentially a bunch of tiny spider-like things living on your face, at least you can take a little comfort from the knowledge that they are clean house guests.

April 17 - Haematomyzus elephantis

The same species of louse, known as Haematomyzus elephantis, is found on both Asian and African elephants. Although it seems like a bizarre coincidence that this parasite should have a long “proboscis” like its host, the length of its mouthparts is an adaptation to penetrate the thick skin of the elephant. And although the ”proboscis” might also look like a giant straw to suck blood, these are not sucking lice (Anoplura) but chewing lice (Mallophaga), which feed on the epidermis. They are so highly evolved that an entire suborder (Rhynchophthirina) was created for only 3 species (the other 2 are found on warthogs).

Contributed by Mike Kinsella.

April 2 - Dolops sp.

Dolops lacks the stalked suckers that Argulus uses for running around on the surfaces of fish. Instead it has pretty hefty hooks that it can use to dig into the skin of the fish to hang on. Just like Argulus, though, Dolops is a really fast swimmer, and if disturbed it can actively swim away with alarming speed. It will survive in the water column without a host just fine, for a while at least. That active swimming also enhances transmission, especially in schooling fish like Piranha, where the next host is just a hop, skip and swim away.

Contributed by Al Dove.

March 25 - Sarcoptes scabei

In the aftermath of the earthquake, aid workers report that scabies has been running rampant in tent cities in Haiti. Scabies is a contagious disease caused by Sarcoptes scabiei, parasitic mites that are hosted on humans, dogs, cats, and other wild animals such as koalas, gorillas, and wild boar. Sarcoptes scabiei are Acariformes, members of the subclass Arachnida (spiders, scorpions, mites and ticks), subphylum Cheliceriformes, phylum Arthropoda. Up to 104 species are known to have been infected with Sarcoptes scabiei, producing a condition called sarcoptic mange. All four stages of the parasite’s life, egg, larva, nymph and adult, take place on the host’s epidermis. The adult female burrows under the skin and lays 2 or 3 of her eggs each day. To enter the skin, the mites use cutting mouth parts and cutting hooks on the legs. As the life cycle progresses, the mites come to the surface of the skin, then burrow into molting patches to complete the stages. Burrowing mites feed on living cells and tissue fluid. The first hosts of S. scabiei are thought to have been humans. The mites then infected domestic animals that later transferred the parasite to wild animals. The movement of the mites into and on the skin produces an allergic reaction and is extremely itchy. On humans, scabies is most common in areas of the body that come in contact with the skin of other humans, such as the hands and arms. Scabies can be treated with prescribed medical cream.

Contributed by Sara Baughn, Bucknell University.

March 23 - Argulus foliaceus

Argulus foliaceus, also known as the common fish louse or the carp louse, is actually not a louse or even an insect at all, but a crustacean. Within the class Maxillopoda, the subclass Branchiura consists of about 150 species of freshwater and marine fish ectoparasites. The genus Argulus is found throughout the world. Argulus foliaceus is native to Europe, but is also common on aquarium and pond fish worldwide. Although the louse shows some host preference, especially for carp, it is usually considered a generalist and is found on a variety of fish species. The oval-shaped, flat adults attach to fish hosts using hooked suckers. They inject digestive enzymes into the host and feed on blood and tissue fluids. Symptoms of lice infestation include abnormal swimming, rubbing, and deteriorating physical condition. Because of tissue damage caused by the parasite, secondary bacterial and fungal infections frequently occur. Adult females leave their hosts and lay eggs on vegetation or other submerged objects. Adults can live free of hosts for two to three weeks, but newly hatched larvae only survive a couple of days if they do not find a host. Treating an infested aquarium may require several approaches, so prevention is best. Always visually inspect and quarantine new fish. Lice may be removed from fish manually with forceps. Fish should be transferred to an alternate aquarium while chemical treatments are used to kill remaining adults, larvae, and eggs.

Contributed by Elizabeth McCarthy, Bucknell University.
Photo from this site.

March 6 - Ctenocephalides felis

The cat flea, Ctenocephalides felis, is by no means restricted to just cats. In fact, it is quite happy taking blood meals from just about any warm-blooded mammal, though it is in fact, most commonly found on cats and dogs. Adult fleas take blood meals from their mammalian hosts and then lay their eggs on the host’s fur. The eggs don’t usually stick there, though and will fall out with the fur into the bedding or other environment. Larvae hatch out of the eggs and then will begin to eat just about anything organic lying around – commonly their parents’ feces, which are of course made of dried blood (shown in photo). The larvae will eventually spin a cocoon and pupate and then the adult pops out and looks for a mammal so it can start feeding. Generally, C. felis does not cause many problems, other than the annoyance of feeling them jump around and bite and the allergic reactions that occur in some animals and people. They do transmit a worm, however. We will meet that parasite tomorrow.

February 11 - Pediculus humanus humanus

In honor of "Fashion Week" in New York this week, six of the posts this coming week will involve parasites that relate to fashion in some way.

Today's: Body lice - I thought it would be fitting to start with these little creatures, which are a little "bonus" that we acquired when humans began to wear clothes.

Body lice, Pediculus humanus humanus (also called clothing lice) are believed to have evolved from head lice, likely invading the body region only recently with the advent of clothing use in modern humans. These wingless insects are found on the body and in clothing and prefer to attach their eggs to clothing rather than body hair. Compared to head lice, body lice are less prevalent parasites, associated mainly with those living in poor conditions in colder climates. Body lice are, however, potentially more harmful because they are known vectors of at least three bacterial pathogens in humans: Rickettsia prowazekii (epidemic or louse-borne typhus), Borrelia recurrentis (louse-borne relapsing fever) and Bartonella quintana (trench fever). Body lice, and the diseases they carry, can be transmitted fairly easily and quickly, especially in crowded situations such as war. In fact, body lice are known to have been prevalent amongst soldiers in Napoleon’s Grand Army and it’s possible that the diseases they carried may have played a role in the French retreat from Russia.

Contributed by Jessica Light.
Image from the CDC Public Health Image Library.

January 25 - Branchellion torpedinis

Leeches are a class of annelids that has many members that feed exclusively on blood and are often found ectoparasitic on their hosts. Branchellion torpedinis is a piscicolid leech that infects a wide range of elasmobranchs (sharks, rays and skates). The individual shown here came from The Georgia Aquarium collection, but they can be found on cownose rays and sawfish along the Atlantic coast. The frilly gills on the side help with respiration. Unlike many leeches, which glue a handful of cocoons containing eggs to the substrate, this species is a supreme egg layer and instead casts large quantities of eggs into the water, more like a monogenean parasite.

Contributed by Alistair Dove.

January 22 - Pediculus humanus capitis

What do parents dread their children bringing home from school more than a bad report card? Pediculus humanus capitis, better known as head lice. These wingless insects, also called sucking lice, have parasitized humans for thousands of years and are now are common worldwide, infesting millions of school children every year. Head lice are entirely dependent on their hosts for their survival (there are no free-living stages), are found on the head and attach their eggs to the base of hair shafts. These parasites are surprisingly nimble, moving quickly among the hairs and can transfer quickly to a new host should the opportunity present itself. Head lice reproduce rapidly and treatment can be expensive and time consuming. Many common colloquialisms resulting from human parasitism of lice include “nit-picking”, “going over with a fine-toothed comb”, “nitwit”, and “lousy”.

Contribution by Jessica Light.

January 16 - Oeciacus vicarious

The swallow bug (Hemiptera: Cimicidae) primarily feeds on the blood of nestling and adult cliff swallows (Petrochelidon pyrrhonota), which are colonial nesters found throughout North America. The bugs are long-lived and remain on the swallows’ mud nests throughout the year, even when the birds have migrated south. Swallow bug infestation can reach up to 2,500 individuals in a single nest and are known to vector Buggy Creek virus (Togaviridae, Alphavirus), which is an arbovirus hosted by birds. This ectoparasite is related to the common bedbug (Cimex lectularius), which is typically found in human environments. Swallow bugs are known to also bite humans when handled.

Contributed by Sarah Knutie.
Photo by Chris Kulhanek.