Monthly Archives: September 2013

The Moth Effect

Like every other genre, horror can be based in cultural roots and societal norms; as a modern, industrial country, the United States has its own themes—ranging anywhere from office romance to racial tensions in the streets. As a result, it is this very industrial situation that disconnects us so much from the mythology of the past and yet enhances the fears of a world beyond a forest. In this case, I am specifically thinking of insects. Indeed, there are a whole slew of horror films dedicated to these creatures:  Arachnophobia, The Fly, Mimic, and Them! to name a few. Being an avid horror gamer, however, I wanted to focus on a specific game, namely Resident Evil.

Now for those not so up-to-date on their gaming, RE narrates the events following a viral outbreak with devastating effects across many species. The series has become iconic for its mesmerizing story, seeming scientific realism, and grotesque imagery.

As I mentioned, the RE series actually tends to seem quite realistic and provides the player with several of the researchers’ notes. For the giant moth on the right side, the following was recorded,

“The research into moth-based B.O.W.s was a failure in this experiment. Mutating it to a larger size did not keep them in proportion, making their wings strong only enough to hover over the ground. However they did also develop the ability to spit poison on prey as a means of compensating for their flight problems.”

            The moth they seem to have based the design off of was most likely the Gypsy moth. Now, after playing these games for a countless number of hours, I had to wonder exactly why a moth would ever be chosen as a specimen. Belonging to the order Lepidoptera, all moths tend to share key traits that unite them. Some of these relevant traits include:

1. All moths undergo complete metamorphosis where the young experience serious physiological changes towards the adult stage.

2. Most moths have a tubular food canal called a proboscis used for siphoning nectar from a plant.

3. Most moths are omnivorous or phytophagous.

4. Moths also tend to avoid human interaction as you can see from this “little” guy below.

 

With that said, I can resubmit the question, “Why moths?”

Consequentially, the type of moth used in the game was a gypsy moth or Lymantria dispar. Gypsy moths have actually plagued the U.S. since their accidental introduction in 1868 and more than a hundred years later continue to be widespread pests with sizeable damage to the environment. Although most do siphon nectar, some moths actually do eat away at foliage. Because of their quick generation times and dispersal through flight, moths tend to be quite difficult to extinguish. So, if the idea to use an omnivorous pest as a weapon wasn’t bad enough, you can throw in the idiotic notion of making this American-specific, uncontrollable pest larger! With their drab and foreign appearance, it is easy to understand why, compared to butterflies, they would be chosen as nightmarish creatures for scientific experimentation, but in all honesty, these moths seem to be as deadly as a puppy fighting a lion.

http://www.fs.fed.us/ne/morgantown/4557/gmoth/

http://www.cals.ncsu.edu/course/ent425/library/compendium/lepidoptera.html

http://www.ucmp.berkeley.edu/arthropoda/uniramia/lepidoptera.html

http://www.capcom.com/us/

Don’t Judge an Arthropod by its Exoskeleton


My previous personal experience with insects and arthropods had generally devolved to how much harm can it inflict upon me, and how quickly can I kill it before it does so? This perspective immediately meant that I would rank each and every one that I’d encountered by the aforementioned categories. Which meant that while some like wasps would earn my undying respect and the fire ants a tip of the hat,  millipedes and caterpillars would simply prove minor annoyances, something that cannot harm me and thus not worthy of my attention.

Man, was I wrong. On September 11th, our Insect Biology class strolled down to the Cockrell Butterfly Center at Houston Museum of Natural Science; this trip would turn out to truly open my eyes. While we did visit the Butterfly Center, we also got an exclusive tour of the exotic specimens that the Center’s biologists cultivated carefully.

Some of the species that immediately caught our eyes proved the Atlas beetle, a gigantic beetle with a huge horn that had a worse bark than bite ;

then came the giant African millipede, or Archispirostreptus gigas.

            I apathetically turned my gaze toward the coiled creature, and I was not disappointed: this one would rank low in my book, perhaps even lower than the fruit fly. Shy and quiet, it lay immobile for quite a while until when it felt more comfortable and started crawling on our tour guide’s arms. 

            “This one may appear scared and harmless, but do not be fooled: his exoskeleton proves very resilient and what’s worse, he excretes repugnatorial fluid that would make you regret your decision to harm him,” quipped Erin, our tour guide, as a student tried to touch the millipede.

            Apparently this fluid, produced by these millipedes just for the sake of repelling potential predators, consists of quinos and hydrochloric acid, which is a powerful acid that can burn through human skin with ease.

            But this center had more surprises in store for me: afterward, we decided actually see the butterflies, which are what the center is known for, after all. Upstairs, we stepped into a somewhat humid cage that the butterflies were kept and bred in; and upon a potted plant lay quite a large caterpillar.

            Erin happily explained that this caterpillar was Papilio polyxenes, or the larvae of a black swallowtail butterfly. Apparently the larvae can have two colorations and ours was a bright green, with black stripes and yellow dots over the entire length of itself.

And once again I couldn’t help but feel slightly bored: this caterpillar literally resembled a harmless, pathetic living being and I wondered to myself how this particular butterfly species could possibly progress past this vulnerable stage to metamorphose?

Of course, as though she were reading my thoughts, Erin helpfully chimed in:

“So these caterpillars might look vulnerable, but when you bother them- (and she started stroking the caterpillar repeatedly)- they will expel foul chemicals that will smell horribly to its predators.”

And fair enough, there was a trace of a foreign smell lingering in the air, and it certainly did not smell like roses. This smell, emitted from an orange forked “horn” on its head called osmeterium, will capably repel birds and other predators.

To conclude, that day was when I realized that I should not allow outer appearances to leave preconceived notions in my head that are not necessarily true, given how complex biological systems can be. And that I wouldn’t want to rub a caterpillar the wrong way.

It Looks So Good You Could Almost Eat It

Every day after dinner, my mother would hand me a White Rabbit Creamy Candy. As she plunked the candy on the table, she would always make sure to offer me some  wise words of advice: “Make sure to eat the candy, because your breath stinks.”

Delicious White Rabbit Creamy Candy wrapped in rice paper (Photo credit: http://www.alohagourmet.com/white-rabbit-candy)

Despite my mother’s brutal honesty, this sweet, milk-flavored candy was a favorite of mine. What made this candy so delicious was not the actual candy itself, which I found too sweet, but the thin sheet of rice paper wrapped around it. I would meticulously pick apart the translucent paper until I had a neat pile of rice paper flakes sitting next to my now, very naked piece of candy. The rice paper had a slightly vanilla flavor from the candy residue, and after a couple of chews, the texture felt very much like congee. It was a tasty treat I looked forward to every night.

Translucent Wings

Translucent Wings (Photo Source: lewisginter.tumblr.com)

Named for its similar appearance to rice paper, the Idea leuconoe butterfly is a part of the Lepidoptera order, and is also known as the Rice Paper butterfly. They have translucent cream-colored wings with black markings and veination, and look so elegant whilst flying, that their style of flying has been likened to that of paper floating in the sky. You can see a video of them fluttering here

Beware though! The Rice Paper butterfly’s similarity to rice paper only gets as far as its outward appearance. Unlike the tasty dessert that masked my bad breath, I. leuconoe has an extremely bitter taste. Not only are these butterflies undesirable to eat, but pyrrolizidine alkaloid, one of the chemicals that contributes to their unpalatable taste, is actually toxic to many vertebrates.

Like other species in the subfamily Danainae (milkweed butterflies), the Rice Paper butterfly also lays its eggs on milkweed plants. Milkweed serves not only as the main source of food for the hatched caterpillars, but it also contains cardiac glycoside, which is a defense toxin that deters predators from munching on it. Over time, the I. leuconoe caterpillar will retain a lot of cardiac glycoside. Then, once it turns into a butterfly, it will accumulate pyrrolizidine alkaloids from drinking nectar. Borrowed from their diet, these toxins in their bodies give them a bitter flavor that they also use as a defense mechanism against predators.

Pyrrolizidine alkaloids also play an important role in the mating process. When female and male Rice Paper butterflies are ready to mate, the male will (I’d like to think, chivalrously) go first and secrete this chemical, along with others, as a pheromone. Releasing this pheromone onto the female’s antennae through his abdomen hairpencils signals his desire to mate with her. After successful copulation, the female will lay her eggs on a milkweed plant, and this heavily protected life cycle will begin again.

A Rice Paper butterfly taken at the Cockrell Butterfly Center, Houston Museum of Natural Science (Photo Source: Me!)

The next time you see a Rice Paper butterfly, remember, you are what you eat. Although it may resemble tasty butterfly-shaped rice paper, eating an I. leuconoe butterfly has more dangerous effects than chewing on a White Rabbit Creamy Candy does. I highly recommend you try a piece of the candy though, and perhaps you can snack on it while you hunt for Rice Paper butterflies!

Of Beetles and Vampire Weekend

Mainstream culture has incorporated a wide array of topics since the modern influx of available information. Since learning bits and pieces about the vast amount of insects throughout all of life, I have seen cultural, menial, mundane examples of their diversity. One such example which piqued my interest occurred one evening while listening to music. The song Bryn by Vampire Weekend exclaims a lyric about the Kansas Palm Beetle: “Nights by the ocean/A westerly motion/That moves California to sea/Eyes like a seagull/No Kansas Palm Beetle/Could ever come close to that free”. So I got to thinking, what exactly is a Kansas Palm Beetle? Is it even real, or simply stylistic and the name was utilized for rhythmic reasons? Is the insect even used in the correct region of California?

After a bit of sleuthing, I have discovered that there is no such insect as the Kansas Palm Beetle. The closest insect I could find was the Red Palm Weevil, Rhynchophorus ferrugineus shown below.

R. ferrugineus is known to be the most damaging pest of palms in the world. Known for their ability to burrow as far as one meter into palms, this beetle threatens commercial crop growth in areas such as: Pakistan, India, Thailand, Egypt, Iran, Iraq, Italy, Greece, Aruba, and Orange Beach, California. It seems as though the members of Vampire Weekend did a bit of research on the topic of palm beetles. Or perhaps, on an even more interesting note, they can predict the future! The song Bryn made its debut in 2008. The first report of R. ferrugineus in California came in October of 2010. I honestly would not expect anything less from the Columbia University graduates. However, the natural predators of the R. ferrugneus do not include seagulls.

The threat of the spread of this beetle is concerning, as areas such as Texas and Florida have a large palm population, both commercial and public. Not many people may know, but dates are produced by a species of palm. The date industry in California alone is worth around 30 million dollars. Insecticides are the most common method of control of this beetle. So far, the spread of this species in the United States has been contained to just Orange County. For the sake of many industries, the eradication of the Red Palm Weevil in the United States is being pursued.

Adult R. ferrugineus beetles are fairly large, attaining body lengths of up to 1.6 inches. Although they may come in a variety of colors, they are known for their reddish-brown color, including a red striped coloration running the entire length of the pronotum for the species present in California.

While they may have been incorrect with the name of the beetle, Vampire Weekend was impressively accurate with their regional anticipation and depiction of the R. ferrugineus beetle. Modern culture is filled with inaccuracies regarding many topics, however Vampire Weekend has enlightened me on the “Kansas Palm Beetle” also known as the Red Palm Weevil, R. ferrugineus through the song Bryn.

Stephen Wallin

Mosquitoes Suck.

After a month of living through Houston’s mosquito season, a single thought has consistently crossed my mind: are mosquitoes more attracted to me than others? I know it sounds crazy and perhaps self-centered, but I seem to consistently come away with more bite marks than those I am with.
PHIL Image 1969

Blood enlarged female mosquito. Photograph by James Gathany, CCD Public Health Image Library.

This week, I set off to find out once and for all if and why mosquitoes are attracted to some people more than others.

The good news is, I’m not crazy! Mosquitoes do seem to be attracted to some people more than others for various reasons. Unfortunately, the question of why can’t exactly be answered once and for all — at least with the information that is currently available. That isn’t to say though that scientists don’t have a good idea about what attracts mosquitoes to people and, perhaps more importantly, what repels them. 

Difficulties in Generalized Answers

It’s so hard to create generalizations about causes of attraction because of the differences among mosquito species that exist. Humans bodies also give off a lot of trackable information too (heat, movement, chemical compounds in body odor, etc.), making it that much more difficult to pinpoint a specific reason.

There are over 3,000 species of mosquitoes worldwide, and many species behave differently from each other in terms of aggressiveness, preferred prey, and the chemicals that they are more attracted to. For example, in a study from the Imperial College London (check it out here), scientists found that different baits were more attractive to different species. The baits used were carbon dioxide and human body odor — both known attractants of mosquitoes. They observed that all species tested were more attracted to both traps as bait concentrations increased, but that there was a difference in which of the baits attracted a larger portion of the mosquitoes across different species. This shows that although the generalization that mosquitoes are attracted to carbon dioxide and chemicals in human body odor can be made, this generalization doesn’t show how the strongest factor of attraction can be different for different species.

Mosquitoes also take into account many different factors when seeking blood, as Dr. Leslie Vosshall explains in an interview with The Daily Beast. First, the mosquito detects the smell of body odor and carbon dioxide (mosquitoes can detect carbon dioxide from 30-40 feet away). Then, as the mosquito moves closer, it is able to detect heat and movement. Finally, when the mosquito lands, it notices taste. Dr. Vosshall notes that in her own experience, mosquitoes will fly towards her and land on her, but then fly off without biting, highlighting the fact that taste can play a roll in mosquito attraction. 

What We Know

Although the complexity of the issue keeps us from a black or white type of answer, scientists do agree that certain things attract mosquitoes in general. For example, carbon dioxide (released from skin and by exhaling) and lactic acid (a chemical compound in skin that is especially present when exercising) have been shown to attract mosquitoes, as seen in the Imperial College study mentioned before.

However, these attractors don’t explain why some people get bitten more than others; we all emit CO2 and have lactic acid. Also, as Dr. Vosshall mentioned, it is only known that body odor and carbon dioxide are very important in a mosquito’s initial attraction.

Mosquitoes avoiding DEET (a mosquito repellent) treated hand on right. Photograph by Greg Allen, USDA-ARS.

Instead of focusing on analyzing what about a person makes them more attractive, researchers have begun to explore the possibility that some people emit extra, repellent chemicals that either mask or actively repel mosquitoes. Researchers at Rothamsted Research in the U.K. have collected and analyzed the body odors of known mosquito-attracting individuals and mosquito-resistant individuals and identified certain chemical compounds that were present in the resistant group but not the attractive group. Many of these chemicals are believed to be related to stress, but it is still not known if stress leads to less mosquito bites. You can read more about Rothamsted Research’s work here and here.

The answer to my question wasn’t as neat and specific as something like “eating bananas attracts mosquitoes” or “taking vitamin B-12 repels them” (both are just wives tales), but then again, nature wouldn’t be as exciting and beautiful as it is if all of the answers were that simple.

Other Cool Mosquito-Related Links

Ants in the Dorm

A few days ago I was hanging out in my room when I noticed I had company.  A group of tiny ants barely bigger than the tip of my pencil were crawling around the surface of my desk. At the time I counted 30-40 ants, and in the last couple weeks they have fluctuated in number from a very few to hundreds each time I look.

These tiny little companions have become a part of my life. We coexist peacefully as long as I remember to keep food out of my room, but how did they get in here in the first place? Are they my friends or my enemies? And do I need to do something about them, or can I stick to the status quo?

Ants are some of the most common household pests, so these are questions many people have to ask themselves. The first question is often the most difficult for people to discover, but I have a hint that leads me to my conclusion. This same variety of ants was present in my summer residence. I discovered these ants in my car after moving here before I found them in my room. Most revealingly, none of my roommates have complained about any ants in other parts of our dorm room. Therefore, I think the ants have been hitching rides on these:

These plants have been present in all the recent places I’ve discovered this variety of ants. I also acquired two of these plants outdoors and kept them in their native soil, leading me to believe that I may have inadvertently encouraged these ants. I don’t think there is a nest in any of these plants because I see no evidence of distress when I water, but there are frequently ant on all these plants, making me think the plants may be attractive to the ants. The ants likely come through openings by the windows, where these plants usually reside, resulting in a number of ants hanging out around the area.

There are many sites that give advice for getting rid of ants that have possibly made homes in potted plants such as this one, but even if my plants are the conveyors of these creatures, the plants don’t seem to be suffering for it, so getting rid of the ants seems like an unnecessary affront to these peaceful scavengers. In addition, Bob Randall notes in his popular Houston gardening book (the online site for this book can be accessed here) that ants are often not an issue in the garden, so I figured that these ants can interact with my plants until I find that they are disturbing the plant somehow.

So the ants remain my friends until some altercation, and we will coexist until such a time. For now I use peppermint (a repellant, according to this) if I want to keep them away from something and I eat my food away from my desk and dispose of it thoroughly. With those two adjustments, are peace is maintained, and no ant massacre is necessary.

Kathryn Hokamp

The Darker the Wing, the Sweeter the Flight.

I have been sighting more monarch butterflies (Danaus plexippus) recently due to season transitioning from summer to fall. The butterflies begin their famous southward from the United States and southern Canada towards the warmer climates of Mexico and coastal California, passing through Houston.
These butterflies go through four stages in one life cycle and through four generations in a single year. Their life cycle involves the stages of the egg, the larvae (caterpillar), the pupa (chrysalis), and the adult (butterfly). The initial generation is a result of the final generation of hibernating monarch butterflies mating and migrating to the north and east to lay eggs. This represents both the first stage in the life cycle and the first generation of the year. These generations of butterflies, as well as the next two, are expected to live for two to six weeks after adult butterfly maturation. The fourth and final generation of the year varies from the initial three because this generation of butterflies do not die two to six weeks after maturation, instead, these adults migrate south and live up to eight months.
It really is amazing to see how all these different biological processes, and environmental factors play a role in Mother Nature’s course. These butterflies have an instinctive nature of migrating south and north even if their generation of adults has never been there before. This migration process is sophisticated for such a small organism. However, is it possible to quantify, or predict migrating capabilities?
The Odum School of Ecology at the University of Georgia has investigated the possible relationship between wing color and flight performance in captive-reared monarchs. Past work has shown that fall migratory monarchs expressed a darker shade of orange relative to non-migratory summer cohorts. It was on this basis that there was an assumption of wing color and flight capabilities being coordinated. A tethered flight mill apparatus was used to quantify captive-reared butterfly flight duration, speed, and distance. Over 90% if the individuals initiated flight after being released, and those that did not, were not included in the data.

Source: PLOSone

Researchers found a strong correlation between wing hue and flight capabilities. There was a negative relationship between flight distance and orange hue of the wings. The individuals with lower hue values (meaning redder wings) traveled farther on the flight mill apparatus within each sex.

Source: PLOSone

The results are consistent with the previously performed study revealing wild migratory monarchs having redder wing colors than those of no-migratory individuals captured in the summer. Both results suggest that the traits that influence flight could be linked with the pigmentation of the wing scales during metamorphosis. While this evidence does not necessarily prove the theory and flight capability may be attributed to other factors, this study represents an important starting investigation of the involved factors between insect movement and aesthetic attributes. This is an important area of study. If we want to future conserve our butterfly conservation, we must learn about them first.

http://ehis.ebscohost.com.ezproxy.rice.edu/eds/pdfviewer/pdfviewer?sid=e16bfe20-67f0-4ef3-b303-64a8ccbf9ff0%40sessionmgr111&vid=2&hid=107

http://www.sciencedaily.com/releases/2012/07/120725220331.htm

http://www.butterfliesandmoths.org/species/Danaus-plexippus

A Visit to the Victoria Bug Zoo

One of the first times I had the privilege of truly experiencing the vast diversity of the insect world occurred several years back when my family visited Victoria in British Columbia, Canada on a vacation during Christmas break. Of course, you may be thinking, how many insects could one possibly encounter in Canada, especially during the winter? Well, the answer to this occurred by chance when we happened walk by the Victoria Bug Zoo and my younger brother became intrigued by the idea of being able to both see and handle exotic insects. At the time, I did not know that I would be taking a course on insect biology, but this “zoo” visit marked the first time I was truly able to appreciate the vast diversity of the insect world.

Ironically enough, this zoo did not only include “bugs,” but was also the home to other orders of insects. So despite being coined a “bug” zoo, the more scientifically correct description of the collection would in fact be an “insect” zoo. (One is left to wonder who is responsible for the misnaming of the zoo, or what the entomologists working there think of this foolish mistake.) Notable residents of the zoo range from giant stag beetles to phasmatodea, scorpions to centipedes, just too name off a few.

When we entered the zoo, I was immediately taken aback by the size and color of many of these mysterious insects hailing from all over the globe. In all, the zoo housed over 50 different species of insects, many of which I had never even seen or heard of before my eye-opening visit. Thinking back on the experience, this zoo visit was a lot like our class’s behind-the-scenes visit to the HMNS Butterfly Center in the sense that it was awe-inspiring and raised the visitors’ awareness of the insect diversity. I was a lot younger at the time of the bug zoo visit than I am now, so perhaps this is the reason why I found the collection of insects to be so impressive and memorable – maybe being physically smaller in size made the insects seem bigger than they truly were!

Of all the insects that I encountered there, the most memorable one was definitely the giant African millipede, or Archispirostreptus gigas. There are multiple reasons why the giant millipede from the zoo still sticks in my memory. For starters, this species is huge – adults can grow to be nearly a foot long. They also live a long life that ranges from about 7 to 10 years. Another fascinating fact is that after each molt, they add more segments and thus more legs, although they never quite reach the milestone 1,000 legs, maxing out at around 400. (http://exoticpets.about.com/cs/centipedes/a/millipedes.htm)

But the most memorable aspect of this creature lies in the fact that they are very docile and can even be handled by kids. Case in point, see the picture below provided courtesy of my mom:

Above is a picture of my younger brother with a millipede mustache. Although I did muster up the courage to handle the millipede with my hands, I was not as courageous as my brother. He was the only one in the zoo that day who volunteered to have the millipede crawl on his face.

So if you ever find yourself in Victoria, have time to spare, and want to acquire a millipede mustache, the Victoria Bug Insect Zoo is just the place for you. For more info on the zoo, visit:  www.bugzoo.com

 

Leafcutter Ants, the Fungal Farmers of the Family Formicidae

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

Ladybugs! Attack on the Orange Powdery Stuff?

This summer I worked in the greenhouses on Rice University’s campus tending to tallow trees, clover, and other plants. Several different organisms invaded the plants, including spiders and snails. The worst of these pests however, were the spider mites.

While watering the plants, I began to notice that many of the clover and tallow tree leaves were fading to a pale yellow, and everywhere I saw yellow leaves there was always what looked like an orange powdery substance on the plant. In taking a closer look I realized that the “powder” was made up of thousands of tiny orange arthropods, the spider mites.

Photo cred: Ariel Nixon
Colony of Spider Mites on Clover
Photo cred: Ariel Nixon

Spider Mites are not actually spiders but they are mites in the order Acari and family Tetranychidae.  They get the name “spider” from their ability to spin silk webs around the leaves of various plants. There are over 1000 species of spider mites alone, and I think the species I saw was Tetranychus urticae, the red spider mite. Although spider mites do not live longer than a couple of days, their numbers can grow exponentially. One female spider mite can lay 20 eggs a day, and each egg matures into an adult in less than a week. This leads to huge colonies like the one seen in the photo of the clover. The mites eat individual cells on the leaves lowering a plant’s ability to photosynthesize and causing the plant to loose coloration. Pesticides and other treatments are usually ineffective against spider mites because of their fast generation times. Each new generation of these insects develops in 5 to 7 days, which means that a single population of spider mites can build resistance to such chemicals in a matter of weeks.

Photo cred: wikipedia.org

My professor and lab manager Dr. Siemann suggested that we order ladybugs to rid the greenhouse of these pests. Yes, it is possible to order live ladybugs from the Internet! Ladybugs also known as Ladybirds and Ladybeetles are in the beetle order Coleoptera and family Coccinellidae. These insects are amazing predators against pests such as aphids and mites that attack crops and other plants. They are actually considered sacred in many areas of the world because of the “good luck” they bring to farmers. There are over 6000 species of ladybugs; the most common species of ladybug found in the U.S. and the one we used in the greenhouses is Coccinella septempunctata. This ladybug has red elytra with black spots. Other species of ladybugs are black, orange, yellow, and even blue. Ladybugs possess the ability to secrete smelly and disgusting substances when in danger. In what is called aposematic coloration, their colorful elytra ward off predators by letting them know they taste bad! Like all beetles, ladybugs have powerful mandibles, which are sharp teeth-like structures that move horizontally. These allow them to munch on several tiny organisms.

Once our package of 4000 ladybugs arrived from California we went through the process of distributing them on the leaves of each plant. This took some time, as ladybugs are quick to fly! Surprisingly, over the next week the number of spider mites decreased substantially as well as the number of other pests. The ladybugs must have had a huge appetite from their trip to Texas!

Watch this video of ladybugs eating aphids!