Author Archives: zdm2

What’s something you can find in your pantry, under your bath mat, or even in between the books on your shelf?

A silverfish of course! And if your reaction to silverfish is anything like mine after seeing a silverfish drop off a pantry shelf and onto your foot, you scream, jump around, then either have someone kill it and dispose of the body, or kill it yourself with a tissue and dispose of the body while pitying yourself. Something about the silverfish’s tiny silver scaly body, or its wiggly fish like movements, coupled with its ability to appear almost anywhere in our homes makes it an especially icky pest to deal with.

Despite the dismay I feel when seeing one of these critters crawling out from amidst the food stored in my pantry, I can’t deny the fact that they are one of the insects I’ll encounter the most in my home and possibly in my life. What better reason do I need than that to spark some curiosity about this small pest of the order thysanura?

Now I’ll ease you into this because I know silverfish might not at the top of your list of interesting insects to read about. These little guys have achieved a little spot in videogame pop culture by appearing in an extremely popular computer game, Minecraft. They pop up, unexpectedly, out of a number of seemly normal blocks and scuttle around quickly, and can even cause other silverfish to appear, creating a swarm-like infestation. This makes for a rather inconvenient event which mimics the real life silverfish that we are all familiar with.

(http://www.listal.com/list/list-minecraft-enemies)

Much like the silverfish in this game which appear randomly out of seemly normal places, silverfish in the real world pop out of all sorts of unexpected places, from books, to bathroom mats, causing me to wonder what in the world they’re doing there and how they’re even survivin. Well it turns out that silverfish’s feeding habits allow, even encourage, them to live in just these places. They feed on carbohydrates which are acquired from a variety of common household objects from books to glue to linen. This means that in large numbers, silverfish infestations can be serious threats to libraries, closets full of clothing, and more.

(http://www1.extension.umn.edu/garden/insects/find/silverfish-and-firebrats/)

There’s more to these little and seemingly un-exterminatable pests which explains their presence in seemingly any given corner of even the cleanest homes. Their sex usually consists of males depositing sperm packets, which females then take in order to reproduce. This is the more primitive form of reproduction which came before the sexual intercourse that more recently evolved insects have.

However there have been instances in which parthenogenesis, or asexual reproduction, has been recorded in these insects. This could theoretically allow the species to continue reproducing even in abnormal or more dangerous situations by just popping out female clone after female clone. On the previously mentioned link about their feeding habits, it is even mentioned that they are sometimes found in unopened packages. Imagine the excitement you might feel upon opening a bag of chips only to find dozens of silverfish because one silverfish egg somehow managed to find its way into the package, only to hatch and clone away for days.

I’ve been using the term silverfish to refer to our squiggly little friend, but in fact silverfish only one of several species of thysanura, also known as bristletails. There are thirteen species of the order thysanura here in the United States. Now all of these species have their own special preferences, but in general humid and relatively warm climates. This is yet another way in which our homes, basements, and attics are such a great place for silverfish to take up residence.

Here is a firebrat, a common species of thysanura found in the US.
(http://www1.extension.umn.edu/garden/insects/find/silverfish-and-firebrats/)

Now you might be thinking, “Man, silverfish are so gross and live all over my house and eat whatever they want,” but why don’t we give them another chance. Change pest into pets! That’s right, why not have a pet silverfish? Because they’re small squiggly and mostly just eat paper? Well that might be true, but different species of silverfish can live anywhere from several months to as many as five years. That’s longer than a hamster. Alternatively, if you really just can’t imagine a silverfish as a pet (honestly I can’t blame you at all), just remember the next time you see a little silverfish running by along the edge of the wall, you might be seeing him again in a few years, after he or she has produced hundreds more offspring!

(http://www.howdoyougetsilverfish.com/)

For much of my childhood, ants meant one thing. Bites. Bites on my feet, hands and head. I was even so lucky as a kid to experience “ants in the pants” first hand. It was awful. Looking back, it wasn’t their fault. I was rolling, running, and rampaging through their colonies day in and day out. I was simply a kid that loved to experience the nature around me, and sometimes that nature responded to my love with ant bites.

Despite some negative experiences with ants, I did have an ant farm or two, being the pre-pubescent biologist that I was, and I took great care to provide my farms with all that I could. I loved watching their colony grow, seeing the varieties of pathways and caverns that they created, and jobs which they performed. While watching the colonies which I tended in my youth, I felt the rumblings of appreciate for their complex social systems and colony organization.

(invisibleagent.wordpress.com)

Now that I study insects and biology, I can more fully appreciate the ants for just how impressive and complex their colonies are. Ants in a colony fill a variety of roles, the most basic of which are probably the workers, the drones and the queen(s). Now for a short overview, the workers perform a variety of roles, including but not limited to foraging, defense and attack, tending to the queen,  work on the nest. Much of this is done through chemical signals called pheromones. They can mark trails to food, announce if one ant is attacked or killed, and notify if a deceased nest-mate if decaying and in need of removal. The drones consist of only males, whose only purpose is to mate with the queen. Similarly, the queen, on occasion queens, exist to be mated with and to produce thousands and thousands of off-spring. If you want to learn more about ants in general, check out the… dare I say it? Wiki article on ants for some interesting and not-guaranteed-factual information.

All of the functions I just discussed are once again only the basic outline of ant social systems. I originally started looking into ants after finding information about the leafcutter ants (which we will definitely get to!), but I actually got quite excited learning about all the variation which exists within ant species that I’ll share just a few other surprising behaviors with you before we move on.

1. Bulldog ants, which are very large, hunt alone, unlike their other eusocial family-mates who primarily have large numbers of foragers which work together, using their eyes to find and kill prey.
2. Certain species will raid other ant colonies, not only to eat gathered food/offspring/ants, but to save larvae and raise them as slave worker ants. However, the Temnothorax ants have been seen to counter this behavior by killing slave making females in their pupae stage.
3. Other ant species will tend to aphids, small insects which feed off of plant phloem, feeding off of their honeydew, and protecting them in a symbiotic relationship.
4. Some ants have even developed traps for larger insects, ambushing them, biting their legs and antennae, as they pass over a net of plant fibers glued together by a specially cultivated fungus. How awesome (and terrifying) is that?

All of these impressive and specialized types of ants build up a lot of expectations for the little leaf cutter ant that I want to discuss, any although they mind not be as glamorous as trap-laying ants, I still think they are truly something to behold. Prepare yourself for the leaf cutter ant.

(Burrard Lucas)

What is so cool about ants that eat leaves? Nothing, these ants don’t eat leaves. They cut leaves, so many leaves in fact that they are found to be the largest harvester of plant biomass, more so than any herbivores or other insects. With highly diverse workers, task specialization is very important, the bigger ants that act as soldiers and foragers, while the smaller ants have the pleasure of tending the gardens. That’s right; these ants collect leaves only to cultivate a fungus farm. The fungus uses the biomass they collect as substrate and the ants then feed off of gongylidia which the fungi sprout.

A variety of even more specialized roles are required to provide for the garden, tend to it, harvest it, and dispose of refuse so that neither the ants not fungus will have hygiene or pathogen concerns. The ants even react when biomass negatively affects the fungus and no longer provide such biomass as substrate. The ant’s only food source is the fungus, and the fungus only exists within ant colonies, meaning they have obligate dependence on one another. In fact the ant genome has changed to make it less adept at feeding off of anything but its farmed fungus. As a result the queen will even bring with her some of the fungus so that she might start her own garden upon the founding of her colony.

Next time you see a row of ants carrying little scraps of leaves, you’ll know that these are not the “ants in the pants” fire ants you so fear. They are workers that fight every day to provide as much as they can for the biggest and most bountiful farms that exist beneath our feet. Somewhere underground their sisters are tending to the harvest, flourishing thanks to a diverse set of roles to fulfill all the functions of the colony, and benefitting from a complex and beautiful mutualistic relationship between the leaf cutter ants and their farming fungus. (http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002007