We've all seen them, those great B-films where a giant, vicious monster from under the sea, or invaders from outer space arrive to cause mayhem across our cities and generally mess up our way of life. In the end, it seems no matter who or what it was that was attacking us, be it Mothra, Godzilla, or some race of belligerent extra-terrestrials, we could always count on the military to save our collective behind.
Unfortunately, with mosquitoes, that might now be the case anymore.
Scientists are reporting that Deet, one of the most widely used active ingredients in insect repellents, loses its effectiveness against mosquitoes shortly after those ubiquitous, blood-seeking winged vermin are first exposed to it.
Deet - the common name for N,N-diethyl-meta-toluamide - was developed by the US Army after the Second World War to help combat insects during jungle warfare. It was used extensively in the Korean and Vietnam wars, but mosquitoes seem to be able to adapt quickly to it.
"Mosquitoes are very good at evolving very very quickly", said Dr. James Logan of the London School of Hygiene and Tropical Medicine and co-author of the study. "There is something about being exposed to the chemical that first time that changes their olfactory system - changes their sense of smell - and their ability to smell Deet, which makes it less effective."
So what I want to know is where does that leave us here in Minnesota where the mosquito constantly competes with the Common Loon for the title of State Bird? Maybe it's time to start digging the bunker in the backyard.
Courtesy Wikimedia CommonsUnmanned aerial vehicles (UAVs) are commonly used in military operations. Micro air vehicles (MAVs) are a subcategory of UAVs that are currently in development and can be as small as 15 centimeters (~ 5.9 inches); their anticipated uses include search-and-rescue, surveillance, detection of explosives, and monitoring of hazardous environments.
Two researchers from the University of Michigan researchers had an idea: instead of building UAVs the size of an insect, why not use the insects themselves? Professor Khalil Najafi and doctoral student Erkan Aktakka engineered a piezoelectric generator that converted the kinetic energy from the wing movements of a Green June Beetle into electricity (45 µW per insect). Their research was recently published in the paper, "Energy scavenging from insect flight," which appeared in the Journal of Micromechanics and Microengineering.
Courtesy Erkan Aktakka
This research was funded by the Hybrid Insect Micro Electromechanical Systems (HI-MEMS) program of the Defense Advanced Research Projects Agency.
University News Release: Insect cyborgs may become first responders, search and monitor hazardous environs
"Water striders don't really stride, they row on the water. But their legs are spindly and don't seem good for paddling. David Hu, mechanical engineer at Georgia Tech, wanted to understand the basic physics of how water striders glide. By filming them stride on food coloring and building his own robotic strider, he found out that the secret to the stride is in the paddle."
Courtesy Bruce Marlin (via Wikipedia Creative Commons)Summer is heading our way and soon the familiar buzzing of cicadas will fill the air. But for some, particularly in the southern and eastern United States, the buzz will become a loud symphony of sound. That's because, this year, the Great Southern Brood will (actually already has in some places) reappear and millions of the insects will soon be crawling out of the ground to overwhelm us with their vast numbers and cacaphonic chorus.
Relax. Last weekend's rapture was a bust (or was it?), and there’s nothing to worry about in the biblical sense. It’s merely the latest appearance of Magicicada neotredecim and M. tredecim, two closely related species of cicada that show up every 13 years in the United States to fill the treetops with their buzzing song.
The most common genus of cicadas in the US is Tibicen and unlike Magicicada, cicadas in the genus Tibicen appear annually, not periodically. After a 2-3 year stint as nymphs, Tibecen cicadas emerge into their adult stage. The full-grown insect measures about 1-2 inches in length with long translucent wings and distinctive green, brown, and black markings on the middle of its body. Generations overlap so they show up every year and can be heard in many areas, including Minnesota, during the hot and steamy Dog Days of summer buzzing to high heaven. It’s that shrill, grating noise that builds in the air and sounds like someone is cutting up cement blocks with a chainsaw. As deafening as it can be, I like the sound, in much the same way I like the smell of rotting leaves in the fall, it triggers memories.
But I’m not sure how I’d feel about Tibicen's cyclical cousins - those belonging to the Magicada genus - that show up all at once in mass periodical emergences and put on huge choruses of buzzing. There are seven species that do this in the US, three in 13-year cycles, and four in 17-year cycles. Periodical cicadas are categorized into broods numbered in Roman numerals from I to XXX. The thirteen-year cycles occupy XVIII–XXX; seventeen-year cycles number I–XVII. Only about 15 broods are still recognized. There are still only seven cyclical species but some species emerge happen at different times in different regions, hence the number of broods. This year it will be a 13-year cycle called Brood XIX , and it is the largest of the 13-year cycles in terms of geography.
The numbers involved in a periodical swarm are huge but, as Vanderbilt biologist Patrick Abbot explains, the vast numbers increase the possibility of available mates and serve as a way to overwhelm the cicadas many predators, which include birds, snakes, turtles, spiders and wasps, and even fungi. It’s interesting that the periodical emergences have evolved into separate prime number cycles. The reason is probably to reduce competition between broods.
“Say you have two populations, one which emerges every five years and one which emerges every 10 years. Then they would emerge simultaneously every 10 years," Abbot said. "Whereas the period between simultaneous emergences between populations with 13- and 17-year cycles is 221 years."
Occasionally, two cyclical broods have been known to emerge simultaneously but usually the overlap is minimal. For example two 13-year broods rising at the same time but in adjacent regions.
During a brood’s synchronized emergence the number of individuals can be daunting. Some emergences have been estimated to contain something like 1.5 million cicadas per acre of land. That amounts to 800 tons (!) of biomass busily buzzing within a square mile of forest. Think of that!
But despite the huge numbers involved in a cyclical emergence, cicadas are pretty harmless, and don’t voraciously eat up crops like locusts do, nor do they sting or bite. The most damage done is by females when they make “v”-shaped slits in the bark of a twig to lay their eggs (I suppose this could feel like a sting if she mistakes your arm for a tree branch). But, come on, even this is nothing compared to a plague of locusts wiping out the summer corn crop.
The word cicada is Latin and means “buzzer” Very apropos, don’t you think? The males of the species spend a lot of time trying to get the attention of female cicadas by vibrating a membrane on their exoskeleton called tymbals. Each time the muscles contract or relax the tymbals they produce a click. Portions of the exoskeleton such as the abdomen or thorax help amplify the sound. The rapid vibration causes a shrill and (possibly annoying) buzzing, and each of the world’s estimated 2500-3000 species has its own distinct sound. The females, by comparison, make a rather boring click with their wings to attract males (I suppose the male cicadas don’t think it boring). You can replicate the female clicking by snapping your fingers in rapid succession a couple times.
When periodical cicada eggs hatch the nymphs drop down and burrow deep into the ground where they spend most of their lives sustaining themselves for several years ingesting fluids from tree roots and developing through five juvenile stages. Scientists suspect soil temperature triggers the emergence. When it reaches 64 degrees F., the nymphs head for the surface. It seems the likely catalyst since emergences in warmer, southern regions take place sooner than those farther north. Whatever the case, when they do emerge, the nymphs crawl up and attach themselves to nearby vegetation where they eventually molt out of their skins. They don’t begin adult activities until after their exoskeletons harden. So for the first 4 to 8 days after molting, they pass through a stage called teneral (meaning soft and tender) before the exoskeleton is complete. The adult stage of a cicada lasts anywhere from a couple weeks to a few months. Very short in comparison to their other life stages.
People eat cicadas in several areas of the world. And the females are meatier and more desired. I suppose the insect is a good source of protein but – there’s no way I’m ever doing that - I’d never eat one. Maybe I shouldn’t say “never”. Some Native American tribes supposedly survived times of famine by eating cicadas.
If you live in or are visiting an area that is or will soon be overrun by an invasion of the Great Southern Brood, rather than cowering in a corner and wailing and gnashing your teeth, head outside, go for a walk, and take in a symphony of cicada songs. While you’re out there enjoying the summer day, you can get even more involved by trying some of these neat cicada experiments. It will take your mind off the fact that you’re surrounded by 800 tons of buzzing biomass.
SOURCES and LINKS
I know, I know, it's not Friday. But I didn't post the Science Friday video last week. (Or the week before, for that matter, and that one's up next.)
This week (last week?):
"Crocuses, robins, spring peepers aren't the only creatures to signal spring. We visited the "Insect Compactor" at the American Museum of Natural History in New York to learn about which bugs to look out for as the weather warms. Keep your eyes on the willow trees--that's where early bees like to hang out."
There's still time to purchase this most unique Valentine's Day gift for your dear, especially if he/she is into entomology or dirty apartments.
Courtesy Rongem BoyoOne of my favorite 20th century writers is the Russian-born Vladimir Nabokov (1899-1977). Many people were (and many probably still are) shocked by the subject of his best-known novel, Lolita, which he wrote in English in the early 1950s. But Nabokov’s use of the language in that book - and others - is at times so exquisite and so finely-crafted, that it’s equally shocking to realize that English wasn’t his native tongue but rather his second language taught to him by his governess while he was growing up in St. Petersburg. He was also well versed in French, so language played an important role in his life, as his many novels, poems, and essays attest. But growing up to become one of the 20th century’s greatest writers was not something he planned, because at age seven he had discovered another passion: collecting butterflies.
Nabokov said in later interviews that had it not been for the 1917 Russian Revolution, he would have probably been a lepidopterist at some obscure museum in St. Petersburg. But fate brought him eventually to the United States where (before publication of Lolita made him independently wealthy) he made his living mainly by teaching literature at Wellesley College and Cornell University. He also volunteered at the American Museum of Natural History - where he learned to dissect butterflies - and at the Harvard Museum of Comparative Zoology.
During the summer months he liked to mix his passions as he explained in the afterword to later editions of Lolita:
Every summer my wife and I go butterfly hunting. The specimens are deposited at scientific institution, such as the Museum of Comparative Zoology at Harvard or the Cornell University collections. The locality labels pinned under these butterflies will be a boon to some twenty-first-century scholar with a taste for recondite biography. It was at such of our headquarters as Telluride, Colorado; Afton, Wyoming,; Portal, Arizona, and Ashland, Oregon that Lolita was energetically resumed or on cloudy days.
Around 1945 he came up with a new theory of migration for the Polyommatus blue butterflies. Without the use of genetics and by studying anatomical features (mostly genitalia), Nabokov speculated that Polyommatus blues found in South America evolved by migrating in five waves from Asia across the Bering Strait. At the time the prevailing migration theories involved land bridges across the Pacific, so no one gave Nabokov’s hypothesis much weight.
Professional lepidopterists weren’t that impressed with Nabokov. They admitted he was decent enough researcher and at describing specimens (his published descriptions numbered in the hundreds) but they didn’t think he offered much in the way new ideas.
But now it seems Nabokov has been vindicated. A new report in the journal Proceedings of the Royal Society of London has determined - through DNA analysis – that Polyommatus blues have indeed evolved through five separate migrations from Asia over the Bering Strait.
“It’s really quite a marvel,” said co-author Naomi Pierce of Harvard. Pierce was part of a team of lepidopterists from England and the United States that made several expeditions to Chile to study and collect specimens of Polyommatus blues, then returned to the lab for gene sequencing and computer analysis of the data. The results showed that the Polyommatus blues did indeed originate in Asia, and were more closely related to that 10 million year-old ancestor than they were to their South American neighbors. But they also revealed that the first wave arrived when the temperature along the Bering Strait was warmer. But that temperature was in decline, and subsequent migrations brought in hardier species of Polyommatus, better suited to colder temperatures that correlated with the temperature range existing around the Bering Strait at the time of each wave. The conclusions matched Nabokov’s hypothesis to a “t”.
“By God, he got every one right,” Dr. Pierce said. “I couldn’t get over it — I was blown away.”
Paleontologist Stephen J. Gould included an essay in one of his many books about Nabokov’s split loyalties between art and science (he termed it “intellectual promiscuity”) proposing if the writer had kept focused on just writing he might have created another Lolita. On the other hand, Gould mused, if Nabokov had only studied butterflies, he could have become a well-known (at least in some obscure circles) lepidopterist. If it sounds like the old adage “you can’t serve two masters”, Nabokov seems to have pulled it off equally well in both arenas. I think had it not been for his writing and the lifestyle it afforded him, he wouldn’t have had the luxury of pursuing lepidoptery as fervently and successfully as he did; and without his butterfly collecting, he never would have written his masterpiece. If you asked the seven year-old Vladimir what he wanted most to be remembered for, his answer wouldn’t have been “writing a great novel”. He had another aspiration in mind, which he fulfilled several years later during one of his summer breaks from teaching. While visiting the Grand Canyon with his wife, Nabokov discovered a new species of butterfly which he named Neonympha dorothea in honor of a family friend who was traveling with them. His satisfaction poured out a couple years later in a poem:
I found it and I named it, being versed
in taxonomic Latin; thus became
godfather to an insect and its first
describer – and I want no other fame.
- On Discovering a Butterfly (1943) by Vladimir Nabokov.
(I doubt you are as big Science Buzz fans as I am, though. Do you have a large, Party of Five-style poster of Liza, bryan kennedy, Artifactor, mdr, Thor, and Gene hanging in your room? Didn't think so.)
Anyway, despite what we might have said, it turns out that eating bugs may in fact be a good idea. But it's a good idea that's never gonna happen. (When I say "never," I mean "not in my lifetime, so as far as I'm concerned, 'never.'")
See, there are lots of folks who eat bugs (it's called entomophagy). And it's not all Fear Factor-style disgustingness—the insects are often cooked and flavored, and, you know, I'm sure they're fine. Like Corn Nuts.
But there are a lots more people who get their protein from eating larger animals, like cows and pigs and chickens and turkeys and stuff. And for a long time some people ate cows and pigs, and some people ate insects, and the world spun along just fine.
Then, not too long ago, people started to realize something: raising enough cows and pigs and things to feed billions of people has a tremendous negative impact on the environment. You have to feed each animal many times its weight in plants before it grows to full size, and all the while its pooping, peeing, and farting. And before you start complaining about how you're too young to read "pooping, peeing, and farting," let me say two things. 1) The alternative was to write "defecating, urinating, and flatulating," and you are too young to read that; and 2) animal poop, pee, and farts have a huge environmental impact.
When animal waste leaks into water sources, it can make them unhealthy to drink, and toxic to live in (if you're the sort of organism that lives in the water. And the various gases (like methane, nitrous oxide, and carbon dioxide) emitted by animals and their waste are a major source of global warming.
So there. It turns out that those of us who eat meat are straining the environment quite a bit.
But what about all those edible bugs? How do they fit in?
Well, a group of scientists from the Netherlands just published a report on that very thing. They compared the emissions of common meat animals to those of a variety of insects, and found that the world would probably be better off if we raised and ate bugs instead of cows and pigs.
See, insects are able to turn the food they eat into protein much more efficiently than cows and pigs, because insects' metabolisms don't constantly burn fuel to maintain a regular body temperature (like the metabolisms of cows, pigs and people do). In the end, for the amount of mass they build, insects produce less greenhouse gases than pigs, and way less than cows. The insects' production of ammonia (a source of water pollution) was also much less than cows and pigs. The long and the short of the research is that if we were to have farms raising delicious mealworms, house crickets, and locusts, we could reduce our greenhouse gas emissions significantly.
But I don't have high hopes for any of that; it's hard to imagine seeing insect-based food items on the shelves any time soon. Here's hoping though, right?
I've been fascinated by ants since childhood. Back then, I loved to watch them working, or use their large anthills for my imaginary and devastating bombing runs, or incinerate them with a focused sunbeam from a magnifying glass (for scientific purposes, mind you). So here's a cool video from the Science Channel about the amazing complexities of an ant colony (or two). The little buggers are still fascinating.
Courtesy Scott CamazineWell, I understand that Science Buzz generally focuses on science in the news, as well as seasonal phenomena, and, frankly, this post doesn’t fall into either of those categories.
But yesterday I was starting to work on the next Object of the Month (I don’t want to spoil anything… but it’s “wasps’), and I came across an article on the tarantula hawk. The tarantula hawk is neither a hawk nor a tarantula—it’s a giant freakin’ wasp.
Growing up to 2 inches long, the tarantula hawk is one of the largest wasps in the world. It gets its name from its habit of paralyzing tarantulas, dragging the spiders back to their burrows (the wasps are that big), and then laying an egg on the tarantula’s living body. When the egg hatches, the wasp larva sucks the tarantula’s juices until it grows large enough to burrow into the hosts body. There it will eat the still-living spider’s organs, saving the vitals for last. When the wasp matures into an adult, it gives up its tarantula devouring ways, and lives off of fruit and nectar. How nice.
Anyway, the article also mentions that the tarantula hawk can have a stinger as long as 1/3rd of an inch, and that its sting is reported to be the second most painful sting in the world, according to the Schmidt sting pain index. (The Schmidt index was developed to the effects of insect venoms only, so I’m assuming that potentially fatal spider bites don’t count.) Naturally, the tarantula hawk’s position on the index begs the question, “What is the most painful sting?”
Answer: The bullet ant, so called because, supposedly, a sting from the bullet ant is like getting shot by a crossbow. I mean a gun. With bullets.
Native to central and South America, worker class bullet ants grow to about an inch, and are called “hormigas veinticuatro” by locals, or the “twenty-four [hour] ant” because the pain from a sting is supposed to remain unabated for a full day.
While the bullet ant will also bite, it delivers its sting the same way wasps and bees do, through a modified ovipositor on its abdomen (that’s all stingers are—egg-laying tubes evolved to inject venom).
The injected venom is a neurotoxin unique to the bullet ant: poneratoxin. A neurotoxin is a poison that affects the nervous system; poneratoxin interferes with the chemicals that allow nerve cells to send electrical signals to each other. So, when other insects and arthropods are stung with poneratoxin, they can be paralyzed (because, remember, you need nerves to control your muscles). When humans are stung with poneratoxin, they just experience extreme pain. Repeated stinging can lead to uncontrollable shaking, and temporary paralysis of the limbs.
But bullet ants aren’t generally aggressive, so how do we know about the affects of repeated stinging? Because some folks get themselves stung a lot. On purpose!
The Satere-Mawe people in Brazil use bullet ants as part of an adult-initiation tradition. (Or an initiation into adulthood. Whatever’s better.) Here:
Now, keep in mind, the tone of that video is pretty ridiculous. (That is, the “look at the weird stuff these weird people do” thing. We all do weird stuff, but other people’s weird stuff is just less familiar.) Also, if you go to the youtube page that video is hosted by, the description says that their hands “turn completely BLACK with poison.” That actually doesn’t make any sense, and it’s not true—the color is from charcoal.
Still, though… wild!
Oh, also, folks who have lived around the ants for a long time have used their stings to treat rheumatism (painful joints, etc), and have found that their bites are so strong that the ants’ mandibles can be used to pull the edges of a cut together, like stitches. The ant’s body is then twisted off, and the head (still biting) is left on the wound as a suture.
But we like the sting gloves. It’s news to me, right?