Fruit body of a parasitic fungus, growing out of a dead ant.
An unlucky ant inhales a spore, the fungus begins to eat the ant from inside, and, in a particularly sinister twist, Ophiocordyceps hijacks the ant’s brain. The “zombie” ant is forced to leave its nest to climb up onto a tree, clamping its jaws into a leaf vein with abnormal force. A stalk sprouts from the now dead ant’s head. This stalk is fruiting body of the fungus, which will produce new spores that rain down onto the unlucky ants below.
Ophiocordyceps seems like a lean mean killing machine in that scenario, but the fungus itself is vulnerable—to another fungus it turns out. A new paper published in PloS ONE models the disease dynamics of Ophiocordyceps with respect to ants and a hyperparasitic fungi, which is the name for parasite whose host is also a parasite. Unfortunately, this hyperparasite is not of much help for the ant, as it only infects the Ophiocordyceps after the ant has died.
The many-times-magnified photos of the Nikon Small World photomicrography contest entrance us year after year, with mesmerizing close-ups of nature’s microscopic marvels. Now, in the first Small World in Motion movie competition, we get to see the world’s wee wonders in action. The three winning films and eleven honorable mentions chronicle circulating blood, budding yeast, gestating eggs, and more.
First Place: This time-lapse video, at 10x magnification, traces the path of ink injected into an artery of a three-day-old chick embryo. As the ink spreads through the chick’s vascular system, the branching blood vessels and beating heart become clearly visible.
It’s a classic David and Goliath story, except there are 90,000 Davids and they all have stings. On the African plains, the whistling-thorn acacia tree protects itself against the mightiest of savannah animals – elephants – by recruiting some of the tiniest – ants.
Elephants are strong enough to bulldoze entire trees and you might think that there can be no defence against such brute strength. But an elephant’s large size and tough hide afford little protection from a mass attack by tiny ants. These defenders can bite and sting the thinnest layers of skin, the eyes, and even the inside of the sensitive trunk. Jacob Goheen and Todd Palmer from Kenya’s Mpala Research Centre have found that ants are such a potent deterrent that their presence on a tree is enough to put off an elephant.
80beats: Parasite-Infested Zombie Ants Walked the Earth 48 Million Years Ago
80beats: Is an Ant Colony’s Caste System Determined by Epigenetics?
80beats: Finally, a Predator to Control the Notorious Cane Toad: Meat Ants?
80beats: Tricky Caterpillars Impersonate Queen Ants to Get Worker Ant Protection
Image: flickr / ebrelsford
What does it take to be a long-living queen? Change your gene expression, say researchers who analyzed both worker ant and queen ant genes in two ant species–making the humble bug the second social insect (after the bee) to get sequenced.
Their results appear today in Science and suggest that epigenetic changes–molecular switches that alter gene expression–may mean the difference between the queen’s long life, and the workers’ short one. Epigenetic changes don’t actually modify the underlying genetic code, instead they’re carried out by mechanisms that act like on and off switches for genes. That could explain how a queen and worker ant can have the same genetic blueprints but very different lives.
“Ants are extremely social creatures and their ability to survive depends on their community in a very similar way to humans,” says [co-author Danny] Reinberg, who is also a member of the NYU Cancer Institute. “Whether they are workers, soldiers or queens, ants seem to be a perfect fit to study whether epigenetics influences behavior and aging.” [Arizona State University]
Here’s one that I didn’t touch on in DISCOVER’s creepy gallery of zombie animals controlled by mind-altering parasites: A parasitic fungus called Ophiocordyceps unilateralis that infects a plain old carpenter ant and takes over its brain, leading the ant to bite into the vein that runs down the center of a leaf on the underside. The ant dies shortly thereafter, but the fungus gains the nutrients it needs to grow this crazy stalk out of the ant’s body and release spores to create the next generation of ant-controlling fungi.
This cryptic cycle has been going on for at least 48 million years.
In a study forthcoming in Biology Letters, Harvard’s David Hughes argues that a fossilized leaf found in a fossil-rich part of Germany’s Rhine Rift Valley bears the scars of the ant’s trademark death bite. The ant bites down hard so the fungus will have a stable position when it grows a stalk out of the ant’s head. But even so, Hughes says, he doubted the mark would turn up in the fossil record—that is, until serendipity reared its random head:
Many children have a “bug period”–a time of life when bugs and creepy crawlies are a source of endless fascination and learning. Naturalist Edward O. Wilson jokes that unlike other kids, he never grew out of his bug period.
Luckily for this biologist, his lifelong passion for ants has yielded a career rich in accomplishment and accolades. He is not just the world’s preeminent expert on the social behavior of ants, but also the recipient of the National Medal of Science and two Pulitzer Prizes for nonfiction. Now, at the age of 80, Wilson has taken a stab at fiction. His first novel, Anthill, combines two of his greatest loves–his childhood home, Alabama, and the ants that have been his lifelong friends.
Described as an “six-legged Iliad,” Wilson’s Anthill draws parallels between human and ant societies. Though there are no ant symphony orchestras, secret police, or schools of philosophy, both ants and men conduct wars, divide into specialized castes of workers, build cities, maintain infant nurseries and cemeteries, take slaves, practice agriculture, and indulge in occasional cannibalism, though ant societies are more energetic, altruistic, and efficient than human ones [The New York Review of Books].
The book’s first and third sections deal with the adventures of an Alabama boy named Raphael Semmes Cody, called Raff. The boy grows up poking around the lush pine savanna of the Nokobee Tract; he’s drawn to its natural wonders, and uses the forest to escape from his parents’ toxic marriage. In this pristine woodland he literally leaves no stone unturned as he discovers the forest’s rich flora and fauna. Raff grows up and heads to Harvard to study law, returning later in life to protect the Nokobee from feckless developers. But fans of Wilson’s science will be most interested in the book’s middle section, where the author inserts a mini-novella describing the trials and tribulations of the ants living in the endangered forest.
In leafcutter ants and honeybees, it’s survival of the fittest sperm. Biologist Boris Baer, for a study out this week in Science, investigated these two species because of their peculiar sexual practices: In one day, the queen acquires all the sperm she’ll need to fertilize her eggs over the course of her lifetime. But in the race to be the top genetics-spreader, the males have evolved a dirty trick. Their seminal fluids actually do battle within the female’s reproductive tract.
To test out the idea, Baer and colleagues exposed the sperm of the bee and ant males to their own seminal fluid, and also to that of other males of the same species. The seminal fluid killed more than 50 per cent of the rival sperm within 15 minutes. “The males seemed to use the seminal fluid to harm the sperm,” says Baer [New Scientist]. When the team studied other organisms whose lifestyle didn’t depend on this kind of polyandry, they didn’t see the same effect.
A jumping spider that passes on eating ants in favor of leafy greens has just been described by scientists. The novel arachnid, named Bagheera kiplingi, is exciting because it is the first-known predominantly vegetarian spider; all of the other known 40,000 spider species are thought to be mainly carnivorous [BBC News]. The study was published in the journal Current Biology.
Found in Central America and Mexico, the order-defying jumping spider eats nutrient-rich structures called Beltian bodies, which are found on the tips of Acacia trees. Trees produce the bodies to feed ants that defend them, which is a textbook example of what’s called co-evolutionary mutalism, and one that B. kiplingi has evolved to exploit [Wired.com]. Despite a primarily veggie diet, B. kiplingi actively hunts its green prey, which sounds bizarre, since the leaves can’t run away. The spider first sits and stalks its target before it dodges through the ant defenses, snatches a Beltian body, and flees to safety.
In an ironic twist, the weaponry of the fire ants that have invaded the American South is also their potential downfall. Entomologists have found that the fire ants’ venom contains chemical compounds that attract their natural foes, the parasitic phorid flies that turn ants into zombies before decapitating them.
The invasive red fire ants first came from South America by boat, and from their original disembarkation point in Mobile, Alabama, they have spread across the South, from Texas to Maryland. Their painful stings and their habit of shorting out electrical equipment make them a serious pest to humans, and biologists have been attempting to control their numbers by importing and distributing the parasitic phorid flies. But until now, researchers didn’t know how the flies homed in on the ants. So researcher Henry Fadamiro hooked electrodes up to the antennae of flies to investigate which of several stimuli prompted nerves to fire. By exposing the antennae to extracts from different ant glands and body parts, the researchers determined that juice from the venom glands got antennae buzzing [Science News].