June 30 - Lampea pancerina

Ctenophores are commonly called "comb jellies" because they have rows of cilia that are fused at the base, giving them an appearance like a comb. These organisms are diploblasts like jellyfish (cnidarians) and once were thought to be very closely related to them. Turns out that part of that assumption came from the fact that one genus, Haeckelia, had cnidocytes, stinging cells that jellyfish use to capture prey. Recently, though, it was discovered that Haeckelia was getting their cnidocytes not by developing them, but from stealing them from jellyfish that they were eating. A while ago, we met a parasitic jellyfish and Lampea pancerina is thought to be the only parasitic ctenophore. The young comb jellies live inside tunicates, but not much is known about this relationship.

The image comes from this site.

June 29 - Gasterophilus intestinalis

Growing up, I was an avid horseback rider and had both a horse and a pony. Today's parasite was always one of the things I dreaded about summer. Gasterophilus intestinalis, the horse botfly, is an annoying creature to horses and horse owners alike. The females are large and aggressive and pester the horses until they eventually alight and deposit small eggs that stick to the horse's hair like glue, most often on their legs. The eggs itch and so the horse licks and bites at it, eventually swallowing the eggs. The larvae then live out the fall and winter months in the stomach of the horse, which can make the horse lethargic and induce colic. In the spring, they are passed out in the feces, where they pupate and then emerge as new - annoying - flies. We would always try to prevent infection by scraping the eggs of the horses' legs using specially made rough sponge-like things - I spent hours doing that each summer!

The photo shows a very heavy infestation of botfly larvae in the stomach of a horse and comes from this site.

June 28 - Parelaphostrongylus tenuis

Parelaphostrongylus tenuis is a parasite of white-tailed deer that lives in the meningeal spaces of a deer's brain and is thus known as "brainworm". Female worms lay eggs that make their way to the lungs via the blood. There, the eggs hatch into first-stage larvae, get coughed up, swallowed, and then passed out. Snails or slugs then come along and are infected by the larvae, which penetrate the foot of the gastropod. Eventually, the nematode makes its way back into a deer, when they are ingested by the browsing deer. The worms penetrate the stomach, make their way to the spinal cord, and then follow this up to the brain to begin the cycle again. As far as we know, the worms don't seem to have a great effect on white-tailed deer, though I suppose they're not known for being particularly smart animals anyway. However, if the worms find themselves in other hosts such as moose, llamas, or goats, the effects can be very severe. In these hosts, the worms cause uncoordination, stumbling and aimlessness, a condition that is very often fatal.

Image comes from this site.

June 27 - Stegotricha enterikos

Stegotricha enterikos is a parasite of oysters and has been found infecting them on both coasts of North America. They are quite prevalent and though they live within the body of the oyster and ingest the epithelial cells of the oyster, they don't appear to induce a great deal of pathology in the shellfish.

The image comes from this site.

June 26 - Botrytis cinerea

Have you ever enjoyed a glass of sweet dessert wine? It's all thanks to a fungal parasite called Botrytis cinerea, or "grey mould". It is a pathogen which can infect a number of different crop plants including beans, strawberries, cucumbers, tomatoes, and grapes. Unlike many parasites, Botrytis cinerea is not obligately parasitic - it can alternate between living as a parasite, or as detrivore which digests dead organic matter. While this fungi is a cause for headache for most farmers, in vitriculture, it is also known as "noble rot". A late infection by B. cinerea in white grapes lead to drying of the grape berries which increase the sugar concentration without increasing acidity. Maybe a good dessert wine brought to us thanks to the "noble rot" would be a good way to accompany the course of parasites you have been enjoying this week.

June 25 - Hydnora africana

Hydnora africana is a parasitic plant that grows on the roots of euphorbs in Africa. For the most part, it grows entirely underground and lacks chlorophyll or leaves. When sufficient rain has fallen, the plant may then poke up a large, but slowly-developing flower that is bright orange. It releases a horrible, putrid odor that attracts dung and carrion beetles, which it traps inside the flower so that they pollinate it. The fruits, known as "jackal fruits" because jackals will readily consume them, are also enjoyed by people, particularly after they have been roasted over a fire. The fruits are also used to treat diarrhea and dysentery and even acne.

June 24 - Zaops ostreum

How many kind of food can you name comes with its own side dish? Well, the eastern oyster (Crassostrea virginica) should be on that list. This week. we've already seen how a trematode infection can improve the taste of oysters, but it seems that oyster also comes with another gastronomic treat in the form of the pea crab Zaops ostreum. Pea crabs (family Pinnotheridae) are small soft bodied crabs which live inside a variety of marine invertebrates, with most species living in bivalves. Zaops ostreum infect the oyster as a tiny first stage larvae, and grow to maturity within the bivalve's mantle cavity, feeding upon food-laden mucus strings produced by its host's filtering action. It is a true parasite in that it causes harm to its host. Not only does it steal food from the oyster, it also forms an obstruction within the body cavity and erode the gill tissue. From a culinary perspective, there are many serving suggestions available for pea crabs - they can be served raw, deep fried, or sautéed, and can be eaten either as a side dish to oysters, or even on their own (if you can get enough of them to make a meal!).

Photo and contribution by Tommy Leung.

June 23 - Bucephalus haimeanus

Do you enjoy seafood? Especially shellfish? Especially raw oysters? Whether you know it or not, the next time you tuck into some raw oysters, there might be a parasite which is responsible for enhancing your gastronomic experience. Usually, having parasites in your shellfish can be seriously bad news. However, apart from the squeamishness factor, the harm caused by your seafood being infected with the asexual stage of a trematode is minimal to neglible.

As we have seen in prior blog entries, the asexual stages of trematode parasites castrate their first intermediate host, utilising it to produce free-living larval stages which are released into the environment. Now if this first host happens to be oysters - which is the case for Bucephalus haimeanus, this has interesting culinary implications. In uninfected oysters, after they spawn they exhaust the all the nutrients and resources they've stored up and become almost tasteless after spawning season is over. However, because infected oysters are castrated, they stay fat and retain their flavor through out the year.

So from a gastronomic point of view, parasitised oysters are a class above their unafflicted brethen!

Contributed by Tommy Leung.

June 22 - Ustilago maydis

Ustilago maydis, also known as Corn Smut, is a fungus which infects corn. The fungal infection usually occurs in the plant's ovaries, replacing the corn kernels with enlarged, distorted "galls" which then produce infective spores that are carried away by wind or rain. Like any good parasite, Ustilago feeds off its host, resulting in decreased yield in the infected crop. From an evolutionary biology view point, it is interesting to note that functionally, Ustilago acts rather like a parasitic castrator which reduces or eliminate the host's reproductive capacity, a strategy that has independently evolved in many parasite lineages. Whereas corn smut is considered as a blight on corn in Europe and North Armerica, in Mexico it is considered as a delicacy. Known as huitlacoche, this 'blight' fetch a higher price on the Mexican market than the corn itself. Its taste has been described as being similar to that of truffle - which is perhaps not too surprising as they are both are fungi that grow in association with a plant host. In addition to being a culinary treat, Ustilago maydis is also a useful lab model organism, used in research into plant diseases, as well as other research into cell and molecular biology.

Contributed by Tommy Leung.

June 21 - Amoebotaenia lumbrici

The parasite for today plays a central role in a gourmet dish, and that culinary parasite is a tapeworm from the genus Amoebotaenia. Amoebotaenia lumbrici, along with a number of other species from its genus, happens to play a starring role in one of the most prized of French dishes. Host of Amoebotaenia are woodcocks (Scolopax rusticola) and swarms of these tiny tapeworms live inside the bird's intestine. Woodcocks (also known as Bécasse) are popular game birds and gastronomically valued for its strong and unique flavour and taste. The woodcock is usually oven roasted whole with its innards intact. After it has been roasted, the intestine is removed to be chopped up and made into a pâté. The unique flavour of the pâté has apparently been attributed to all those little tapeworms which are packed into the woodcock's gut.

So if you ever find yourself in a fancy French restaurant, check if Bécasse pâté is on the menu!

Contributed by Tommy Leung.