Since I'll be heading into the eastern Harz mountains, also known as Tick Country, I just got my final vaccination against tick-born meningoencephalitis, just to be sure. No better opportunity to introduce a piece about my smallest travel companions along this trip.
Our expert in residence today is Rob Deady (ecologist and former Msc. student at University College Cork)
Rob is an ecologist with a Bsc. in Ecology and an Msc. in Zoology. His main area of expertise is concerning entomology where he has a keen interest in the Diptera or (true flies), their taxonomy, diversity, life history, application in forensics, role in the spread of disease and their place in the world of art.
Black flies, White Socks and River Blindness
To begin with I would firstly like to say and furthermore reiterate that this article has nothing to do with a certain Major League Baseball side based in Chicago, U.S.A. In point of fact the "White Sox" as they are known have not achieved anything of note since 2005 when they won the World Series for the first time since 1917, I'll have you know. Sorry, I have no idea what I just wrote there! Nor, do I care particularly. I must however acknowledge this information that was kindly provided to me by an avid baseball fan who enlightened me on hearing the above article title. Ahem...tennis, now there's a game and a half! A game I like to think I understand in its entirety! Alas, it is raining outside so no tennis today...boo hoo! It is a day, however, to mull over my thoughts I think, and write this!
The intriguing though reasonable thing about science the natural world and its perception and appeal in society is this: If I was to rephrase the above title to.....oh say this: "Onchocerciasis and infectious diseases due to Dipteran vectors", you'd switch off, wouldn't you? The average Joe Soap wants to understand the world around them, the organisms that coexist with them and the cogs that make things....well.....work. I to this day still get annoyed when I read a paper where fancy, technical terms are bandied about instead of the morecomprehendible and usually more appropriate alternatives. I am guilty of it myself and have tried where possible to correct myself while challenging this tendency in my peers in order to help all of us understand better.
Right that's my rant complete for the moment! I've already digressed as usual.
MORE TO THE POINT!
I always get a rather good laugh out of some of the common names that have been given to various insect species which I have continually come across since I was a kid. No see-ums (biting midges that ravage folk particularly in Scotland), Billy witches (scarab beetles also known as Cockchafers or May bugs) and finally White socks, the last of which inspired this article. Hell, maybe Major League Baseball did give rise to the name!? Let me enlighten you and most importantly Gregor!
Black flies, turkey gnats or "White Socks" as some are colloquially known as in parts of the U.S. are a family of biting flies belonging to the Simuliidae family in the world of the Diptera or true flies. The Simulium genus is by far the most well-known genus as many of its 700+ members (sounds like I'm addressing a convention of critters) transmit infectious diseases such as river blindness or Onchocerciasis (Gregor's affiliated charity Fighting Blindness will be all but too aware of this horrible disease), bovine Onchocerciasis (cattle blindness) and leucocytozoonosis (an immuno-compromising infection leading to gauntness and emaciation in wild birds). The "White Socks" include Simulium venustum amongst other members within the Simulium genus and are also known as "White stocking" flies because of the rather evident bands of white coursing the legs of individuals. These flies do not spread the majority of the above mentioned infectious diseases nor do the species that reside within the British Isles or mainland Europe but they do bite so Gregor will have to be wary! When I first started out looking at flies, I used to call Black flies "Slinky flies" due to the flies' stout appearance, stubby antennae and almost concertina like abdominal segments giving the impression of a compressed slinky. In entomology we'd call this appearance anteroposterior compression like the poor so and so has been in a head on and rear collision at once. Sufficed to say, nobody caught onto my Slinky fly name! Oh well.....
Right, let’s explore river blindness, what it is and how it's spread to help make us more aware of this horrible disease. River blindness is also known as Onchocerciasis. The word Onchocerciasis is derived from the nematode (worm) parasite Onchocercavolvulus that ultimately leads to infection. The genus name "Onchocerca" probably originated from the Greek “ónkos” meaning mass or bulk and the Greek “kérkos”meaning tails. This probably refers to the tendency for this organism to clump in a mass in human tissue. An infected female Black fly burdened with Onchocerca nematodes (in need of a blood meal for its eggs that reside in its abdomen) will bite its human host transferring the parasites in the process. The nematodes once inside the new host eventually die releasing their endosymbionts: Wollbachia pipientis. There is then a rather large human immune response to these endosymbionts leading eventually to destruction of optical tissue if untreated. So you see, it is not the Slinky fly, nor the nematode but the endosymbiont that leads to this debilitating condition. Having said this, it is the cocktail of the three that provides the means to spread the disease. More often than not for Onchocerciasis to take a hold multiple infectious bites are needed thus increasing the "payload" of nematodes.
Lovely, I hope you weren't eating while we were visiting this issue! If so, I apologise profusely! However, it is a condition that is worth raising awareness for. Particularly for the poor folk living in places like Burkina Faso, other African countries, and the Americas.
With regards to biting flies, all I'd suggest to Gregor is to steer clear of: 1) stagnant water bodies where mosquitoes are likely to breed 2) running water where Black fly larvae dwell and finally dark, dank forested environments where the infamous No-see-ums or biting midges will be partying till all hours of the morning! Failing this, he ought to lather on copious quantities of his trusted N diethyl-m-toluamide to shatter the antennal receptors of the various Dipteran vampires roaming the night (ahem they are my buddies though Gregor so don't kill too many!).......Next time...ticks, glorious ticks!