Insects are Not Taboo: My Personal Relationship with Terrestrial Xenomorphs

16 January 2014 by Jack Scanlan, posted in Biology, Genetics, Insects

The first post on a new blog is always a tough thing to write, especially when you’ve been invited onto a pretty serious science-blogging network. (Sorry about the title by the way, SciLogs.) But I think I’ve made it harder for myself by intentionally picking a topic with so many dimensions that I could hardly do it justice with a single post.

So I won’t. Consider this an introduction: both to this blog and to myself.

Hi, my name is Jack, and I like insects. Welcome to When Two Substances Collide.

My passion for insects crept out of nowhere, like many people think the little critters always do, scuttling through the dark and onto your face when you’re pretending to sleep. (Take my word for it, most of them don’t do that.) It also evolved over time, like insects definitely did, along with the rest of life on Earth. And it surprised me, like insects continuously do, with all their neat tricks and cool bodies. Am I constructing the most meta analogy ever? Probably not, but it’s close.

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Insects were never my first scientific love. That was evolutionary biology, probably due to a combination of Richard Dawkins, YouTube videos, and a school that pushed advanced biology onto its students relatively quickly. I found there to be something almost unspeakably beautiful about the ever-lengthening and splitting limbs of the tree of life, new species and things coming into existence simply because that’s the way the life works: it evolves.

However, throwing a teenager into arguably one of the most abstract and theoretical areas of biology is bound to have some weird side-effects… so for many years I was obsessed with intelligent design (ID) and creationism. Not in an “Evolution is a liberal lie!” way - more in an “Evolution is so not a lie it’s not funny - so why do those guys over there seem to hate it so much?” way. I wanted to know why these religious ideas in opposition to solid science were wrong, and how I could help fight the battle for scientific literacy.

It just so happens that ID and creationism aren’t huge issues in over here in Australia, at least within our public school system, so my interest gradually faded. While I still check up on the issue from time to time, progress in the ID movement is slow, so I decided to move on. Or at least, that’s what I tell myself. Perhaps anti-ID activism is lying dormant within me, like some sort of chestburster from Alien.

Nature abhors a vacuum, so I needed to replace my waning interest in religious opposition to evolutionary biology with something. So why not dig deeper into evolutionary biology itself? I was at the start of my Bachelor of Science degree at the time, and the only major on offer that would bring me close enough to the heart of evolution was Genetics. I quickly learnt that genetics underpins all of evolution - I mean, I had already known that in an academic sense beforehand, but it suddenly clicked in my mind that all evolution takes place at the genetic level. Variation in DNA sequences are squeezed and squashed and mixed through populations under the influence of the environment, leading, over many millions of generations, to the extraordinarily diverse collection of organisms the planet is currently teeming with.

Simple. If you understood genetics, you understood evolution. More or less. Kinda.

But that was enough to propel me headlong into DNA-ville, and I’ve never looked back. Only… sideways. You see, the thing about genetics, historically, is that it is dominated by insects. Well, one insect in particular: Drosophila melanogaster, the common fruit fly (or vinegar fly, if you like, but trust me, they prefer fruit over vinegar). Modern genetics owes an incredible amount to this fly species, and it remains to this day one of the best characterised organisms on the planet, helping to probe the basic systems of multicellular life (and animals in particular) in countless labs all over the world.

Many of the labs at my university work with fruit flies, so I was constantly exposed to them in classes on evolutionary genetics, molecular genetics, developmental genetics... Flies - and therefore insects - were genetics.

If you take a thing you love (genetics) and wrap it in a cool thing (insects), you start to love the cool thing. It's just basic psychology, people.

It wasn't until I started undergraduate research involving fruit flies that I was driven over the edge into full-time insect-loving horror. It wasn't really the fruit flies themselves, to be honest - they're nice and all, but kind of plain - but the thing they represented: the absurdly interesting world of insects.

It's taken a while to get to this point, but here's the main reason I love the critters: they're essentially aliens that just happen to live on Earth. They're terrestrial Xenomorphs. Their bodies and lifestyles are so different to our own that I feel there's no way you can't be interested in them. Screw searching for life on local planets, I think we've got enough insect species hanging around the local fruit market to last us, research-wise, until the Sun expands to engulf the inner solar system.

(Okay, I don't really mean that. Discovering life on another planet would be the greatest scientific discovery of the century, perhaps even of all time.)

I feel some examples are in order. So hold onto your hats - if you're not even a little bit more excited about insects after reading this than you were before, you're either an entomologist (laughing at my cursory knowledge) or an artificial intelligence algorithm from the 1990s.

Aphids! These guys piqued my interest as soon as I started working in my current lab, due to a new project that was starting up. There are too many cool things to mention about aphids, but my favourite is telescoping generations - a fancy name for what is essentially giving birth to pregnant clone children. Pregnant clone children!

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Some aphids are parthenogenic: females can give birth to genetically-identical copies of themselves - no male required. Add to that their ability to give birth to live young, and you have a recipe for some amazingly weird reproduction.

Of course, aphids aren't the only insects with freaky reproductive habits (far from it). Some species of wasps are parasitoids and lay their eggs inside the still-living bodies of other insects, such as caterpillars, beetles and ants. The wasp larvae then hatch from their eggs and eat their host from the inside. Delicious

What makes this phenomenon particularly next-level, in my opinion, is the existence of hyperparasitoid wasps, who extend metaphorical middle fingers to their kin and lay their eggs inside the bodies of other parasitoid wasps. Nature, red in tooth and claw... and egg.

Other insects don't have to do some crazy thing to hold my attention, though. All insects are pretty, but it doesn't really need saying that some are prettier than others. Blue bees are a particular favourite of mine. Hymenoptera (members of the taxonomical category that includes bees, wasps and ants) are gorgeously other-worldly most of the time, but combine that with a colour rarely seen on an animal, and you've got yourself something very special.

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The blue banded bee (above) is an Australian native species - and a gorgeous, blue-tinged ball of fuzz. The chequered cuckoo bee (below), while also being native to Australia, is far less subtle. Bees run the spectrum! Interestingly, the chequered cuckoo, like hyperparasitoid wasps, is parasitic to other Hymenopteran species, but in a different way: it steals the food of other bees and wasps, rather than laying eggs in them. I'm not sure which one is meaner.

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Insects can also be interesting in the way that they interact with species other than their fellow insects. My current research project (which I'm sure I'll write about in the future) is partially involved with plant-insect and fungi-insect ecological interactions. Funnily enough, there's a huge arms race between plants and fungi and the insects that want to eat them, and most of the weapons involved are chemical. (Don't tell the UN!) But it's not quite as straightforward as concocting nasty poisons...

Some basic insect biology: unlike us, insects have exoskeletons, which means that if they want to get physically larger, they need to moult and shed their hard outer layers. This process is controlled with steroid hormones (one of them, ecdysone, is shown below), and when and where these hormones exist in the body of a growing insect is of vital importance. Larvae don't want to be exposed to high doses of moulting hormone before they're ready to moult or they'll die - and many species of plants and fungi use this to their advantage by synthesising their own insect hormones and loading them into their most delicious tissues (particularly leaves, in the case of plants).

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These hormones do nothing to the plant physiologically - they're chemically specific to insect development - but they wreak havoc on larvae that consume them. However, some species of insects, particularly those that love to eat numerous types of plant crops, are well-adapted to the hormonal onslaught and typically not badly affected. One can imagine plants planning a more vicious assault in their evolutionary future...

The thing is, you rarely find things like that - using a predator's own chemicals against them. It's like a chicken pumping itself full of testosterone in order to make anyone who eats it hairy to a deadly extreme.

The last cool insect thing I'll mention in this post (and don't worry, there's plenty more where these came from) is their relationship with bacteria. Now, you might be aware of new research that is linking your gut bacteria with various states of health or disease, but many insects take it a lot further than simply the gut, which is technically outside your body if you think about it. Some species of bacteria live inside the cells of insects, supplying them with everything from nutrients to defence capabilities.

A good example of this comes from the pea aphid - yeah, aphids are cool for many reasons. It has a long-standing endosymbiotic relationship with the bacterium Buchnera aphidicola, which lives in specialist cells called bacteriocytes. The aphid's diet, plant phloem, is notoriously low in certain essential amino acids that it can't make itself, so it uses the metabolic powers of its internal Buchnera factories to churn them out inside. In return, the bacteria get a nice place to live and a plentiful source of energy - what phloem lacks in amino acids it overcompensates for in sugar.

While pea aphids need Buchnera to live, other bacterial endosymbionts are more optional, although no less useful. Aphids are also victims of parasitoid wasps, and a beneficial infestation of the endosymbiont Hamiltonella defensa is known to protect against the successful egg-food-ification of adult aphids. It'd be nice if bacteria worked the same way in humans, but they don't! Then, we don't need to be on the lookout for wasps laying eggs in our skin. But flies, on the other hand...

So there, that's an overview of why I love insects. They're aliens, they're just straight-up, fascinating aliens, and most people view them only as pests or evil creepy things, not realising a different world of creatures lies at a slightly smaller scale all around them. While some insects are undeniably evil, that doesn't make them uninteresting - just look at the popularity of horror movies! And for everyone who shies away from those films (me included), there are other facets to insects, like their beauty and their general awesomeness. So there.

I hope you understand me a little better now. I think I sure do.

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Creative Commons-licensed images used:

  1. http://www.flickr.com/photos/graibeard/5399443359/
  2. http://www.flickr.com/photos/dotcomdotbr/8891100159/
  3. http://commons.wikimedia.org/wiki/File:Aphid-giving-birth.jpg
  4. http://www.flickr.com/photos/bareego/5627588222/
  5. http://www.flickr.com/photos/boobook48/6833241535/in/photostream/
  6. http://en.wikipedia.org/wiki/File:Ecdysone.svg

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