Best of youtube #6: The Guild

If you're a fan of Joss Whedon, you'll certianly recognize Felicia Day.

It's a series about a group of people who are addicted to a World of Warcraft type game.

Announcement

As of late, I've become...dissatisfied with the way this blog is working out. There are a handful of good reasons, but mostly it's the blogspot layout.

I'm going to start to work on a new version, but it's going to take time. I've been nosing around the labs here at ISU, looking for research opportunities and such so I don't have as much time for writing as I used to.

I'll be launching a new blog here shortly. I'm going to post one more article and after that, I'll be launching a new and improved version of this very same blog next month.

Expect some changes. in both layout and content...all of them good.

Best of Youtube #5: 2 AM

Yeah, I'm probably going to lose my reputation as a badass by posting this. But I love Anna Nalick. Her music is poetry and even though it sounds like a standard pop song if you listen to her lyrics, I think you'll find they're actually very poetic. I love her voice, too. And she's hot.

Totally made of win.

Sericulture Biological Control Part One: The Background

The production of silk (also known as sericulture) is a huge worldwide business which supplies millions of people with jobs every year and produces billions of dollars worth of imports and exports every year. In 1997, the US imported about $ 2 billion in silk products. Although silk makes up about a fifth of a percent of the global textile trade, its importance cannot be understated because raw silk fetches about twenty times more per weight than raw cotton.

Silk is unique among the textile world in that it’s a naturally produced fabric that comes from an animal. Many animals produce silk, mostly larvae of various moths as well as some arachnids (most notably spiders, but also mites). The vast majority of silk on the market comes from the silkworm moth Bombyx mori which is a species which is believed to have been cultured from Bombyx mandarina sometime about 5,000 years ago. It’s an interesting evolutionary story, but one we’ll have to explore another time.

B. mori was first domesticated by the Chinese sometime around 5,000 years ago and as the new millennium dawned, sericulture began to spread around the world as a result of the demand for silk prices and industrial espionage. This meant many new opportunities for people trained in the art of sericulture, and unfortunately those new opportunities for people also meant new opportunities for parasites. If we’ve learned anything from cockroaches it’s that if we give insects an inch in the form of a semi-habitable habitat with strongly reduced predation they’ll take a mile and refuse to let it go no matter how many nerve gasses we bomb them with. Unfortunately, the types of pest sericulture attracts are a lot more bothersome-and gruesome than cockroaches.

Life as a caterpillar is tough. You rarely make it to adulthood. If you’re lucky, you get eaten by a bird. If you’re not lucky, you fall prey to a parasitic wasp or a tachinid fly. Sure it sounds odd that I’d consider being ripped apart by a bird a decent way to die, but if you’re eaten by a bird at least it’s quick. If you happen to be attacked by a parasitic wasp or fly, you’re eaten from the inside out over a period of about two weeks. Remember the movie Alien? Yeah.

Exorista bombycis (also known as ujifly or uzifly) is a tachinid parasitoid which attacks either Bombyx species. The female who finds her victim by smelling it’s poo (or frass, as entomologists call it) lays eggs on the outside of the silkworm, usually in folds of skin. The thing to remember is that if you’re a silkworm, you’re pretty much a bag of fat reserves with a pair of mandibles. You can try to whack the fly as hard as you can, but the fly is a whole hell of a lot more mobile than you are so unfortunately, you can put up a hell of a fight if you want…you’re still pretty much defenseless. Fifteen hours to four days later (development depends on temperature), the egg hatches and the fly maggots begin to burrow into you and eat you from the inside out for about a week or so. The larvae are actually pretty big…about half an inch or so and there are more than one per host. They burrow out of you and turn into a pupa about half a day later in some nice, secluded area.

This fly is actually a pretty serious pest. Each female can lay between 100 and 1,000 eggs, so as you can imagine, things will get out of control very quickly during an infestation. Unfortunately, people don’t inspect their silkworms as much as they need to and that’s how this pest spreads. E. bombycis was first recorded as a pest in the north-eastern sericultural regions of India and was best known in Bengal and Assam. As a result of poor inspection of transported animals, the pest was carried all the way to the Karnataka province and first recorded in 1980. Two years later, an across the board average of 40% losses were recorded and many silk producers faced almost an 80 to 90 percent drop in silk production. Many were also put out of business by repeated destruction of their silkworm crops.

Silk producers face a unique challenge from the standpoint of pest management because this environment is unique to pest control. Their main product is an insect which is reared indoors, so they can’t exactly spray an insecticide on their field like my neighbor occasionally does. Insecticides aren’t entirely out of the picture…ovicides have been developed and used with success and there’s a bacterium (a strain of Baccillus thuingiensis) which is pathogenic to the ujifly. Sericulturalists do their best to fly-proof rooms with nylon screens and install fly-proof window screens to block the flies from rearing facilities. Sterile releases (remember this post?) have also been tried, and workers try to remove infected silkworms, as well as any E. bombycis maggots and pupae they find. They also try to use various attractants to lure the flies to their deaths, but they still keep on coming.

So what’s a silkworm farmer to do? You can’t use pesticides…you’ll kill your crop. You have some luck with the ones you can use, but they’re definitely not enough. You’ve done your best to block the pest from your facilities…but let’s face it. They’re flies. No matter how hard you try to keep them out of your house during the summer, you eventually find one dead on the window screen or running into a window, trying to get out. Tachinids are good at finding their hosts. They’re parasites…it’s what they’ve evolved to do. You need something which is good at finding tachinids. You need a parasitoid that parasitizes your parasitoid and nothing else. You need a hyperparasitoid.

T.K. Narayanaswamy, R. Govindan (2000). Mulberry Silkworm Ujifly, Exorista Bombycis (Louis) (Diptera: Tachinidae) Integrated Pest Management Reviews, 5 (4), 231-240 DOI: 10.1023/A:1012982030848

Best of Youtube #4: Bacillus thurigiensis

Bruce Tabashnik explaining how B. thurigiensis is used to kill insects.

B. thurigiensis is kind of a cool bacteria. It's found on plants and in the soil and it's evolved to cover it's spores in a highly toxic protein that dissolves the gut of the poor insect that happens to eat it. Once the insect is dead, the bacteria can feast to their heart's content until the food supply runs out. At this point they form spores and the cycle starts over again. Each strain is adapted to different species of insects. There's a few different strains which go after butterfly, moth and beetle larvae and even one that infects parasitic flies. Each strain has it's own very narrow host range and none effect humans.

Many crops, corn and cotton to name two, have been genetically modified to produce this toxin within it's tissues. However, some have evolved resistance to the toxin. Fortunately, the mutations which grant resistance to BT have so far been recessive alleles and easily controlled by introducing susceptible variants to spread their genes amongst the immune genotypes.

New Sciency Stuff Coming Soon...

I'm actually working on a few things right now. Both about parasitoids...expect them soon.

But let's review exactly what a parasitoid is. A parasitoid has characteristics of a predator and a parasite. They live within their host, taking nutrients from them kind of like a parasite. However, very much unlike most parasites, they eventually kill their hosts as well.

Let's take a tapeworm, for an example we can use to contrast between a parasite and a parasitoid. The dumbest thing a tapeworm could do is to kill it's host. Why would it? It's got it made-nice safe environment in the gut of some animal that keeps it safe. All the food it could ever want delivered to it...it doesn't have to chew, that's done by the host. All it's had to do to survive is evolve into an inside-out intestine and become hermaphroditic.

Remember this scene from the movie Alien?





You know, the creature that emerges from Kane at about 2:00 in?

That's what a parasitoid is. A bit of a greusome example but to me, parasitoids are only beautiful because they're so damn ugly in the way they live their lives. All parasitoids are larvae. They're either hymenoptera or diptera...wasps and flies, respectively. There's a few butterflies and beetles which are parasitoids as well. Even though parasitoids are extremely different from one another, they all have an adult stage that's free living. This is why they can afford to kill their hosts.

True parasitic relationships in the insect world are rare. The only example that immediately comes to mind is Strepistera...twisted-wing parasites which live inside wasps. They actually do some really cool things, like extend the lifespan of their host.

They come in two flavors...idiobionts, which eat their host as-is and don't allow it to grow or moult any further and koinobionts which benefit from the extended development of thier hosts, usually not killing their hosts until they pupate. Parasitoids can either live inside or outside their hosts. If they live on the outside of their hosts, they're called 'ectophagous parasitoids'. Ecto = outside and phagous = eating. Parasitoids that live inside their hosts are called endophagous parasitoids, which means 'inside-eating'.

Parasitoids that parasitoids parasitoids are hyperparasitoids. Parasitoids that parasitize parasitoids that parasitize parasitoids are 'tertiary parasitoids' so on and so forth. It's confusing as hell, but that's what I'm here for.

So...why do I love parasitoids so much?

Well, they violate everything we hold sacred. They violate the body by burrowing inside it and consuming it from the inside-out. They violate the mind by taking control of their hosts. They violate this absurd notion that life is sacred by using their host until it can't give any more and then killing it. Any notion that we might lose our spot at the top of the food chain is absolutely horrifying to us...and Hollywood plays on those fears in many big and low-budget movies. It's definitely not a bad thing...I'll be comparing parasites to various Hollywood monsters in many of my posts.

Parasitoids have some really cool adaptations to compete amongst themselves and to subdue their hosts. Some are neurosurgeons, and I've mentioned that some take over their hosts. Some fight wars inside their hosts, and some produce their own viruses. Some parasitize other parasitoids and some parasitoids even parasitize themselves.

So. Yeah. Parasitoids are really cool. They really are miniature real-life horror movies. Because, you see, we have creatures almost exactly like the creature from Alien here on Earth...it's not a unique creation of Hollywood.

Critters which are known as bee-flies (Family Bombyliidae) actually resemble the creature from Alien even more than the hymenoptera (parasitic wasps) it's generally associated with. Remember how Kane first got acquainted with the critter from alien?

Well Bombyliidae actually have a similar manner of host location, where the larva finds the host after the adult lays the egg. The first instar larvae of these guys kind of have legs and actually look for their hosts. When the larva finds a suitable host, the larva burrows into it, moults into a maggot that looks a bit more familiar, feeds and then exits it's host as parasitoids do. Then it pupates and emerges as something which looks a lot like a bumble-bee.

So Alien isn't exactly a new creation...we've had something like it for a few million years or so. It was just a little bit smaller than we expected.

Oh, Ray Comfort says he's not a prophecy buff...

...but you just know that when something goes awry, he's praying for the world to end.

Just in case you've lost track of the score, here's where we stand:




Yup...instead of overhauling the US bank system, we need to start hoarding food and preparing for the four horsemen.

Just out of curiosity though...if this is a sign of the coming apocalypse, why didn't the world end in 1929?

So I'm horrible at this whole blogroll thing...

...and I've finally started one.

Check them out in my profile.

New Sciency stuff coming real soon. I'm switching gears a bit because I have a major case of ADD, but I think y'all are gonna like it.

I'll return to the whole history of entomology thing soon-ish. I still need to go over what happened when Koeble landed in Hawaii...the story isn't over.

But I'd like to go through some parasitoid basics first...some extremely odd aspects of their different lifestyles and how they're used in biocontrol.

We'll begin with exploring exactly what parasitoids are, then adelphoparasitism and then explore biological control with hyperparasitism before careening into tachinid metamorphosis.

You ready?

Best of youtube #3: Parasitic Nematodes

Parasites do some really cool things.

I'm writing an introduction to parasitoids right now. I tend to change focus quite a bit...but don't worry. I'll get back to the biocontrol articles soon. There are some pretty good stories in the literature...triumph and tragedy.