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]
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If you’re a tobacco hornworm caterpillar, your own spit can come back to bite you: That plant you tried to eat for dinner can use your own saliva to summon larger animals that might like to make you their dinner.
According to a study in Science, the tobacco plant has evolved a clever defense against hungry insects—it calls in the insects’ predators for help:
When a leaf is wounded, plants immediately release a “bouquet” of distress chemicals known as green leaf volatiles (GLVs) into the air. GLVs are formed when long fatty acid chains in the cell membranes are chopped up into six-carbon molecules as a result of damage. These molecules can exist in two different shapes, or isomers, depending on the position of a double bond between two of the carbons [The Scientist].
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Teamwork: That’s what it takes to get lucky (if you’re a certain kind of firefly).
Suppose you’re a single male firefly, fluttering about on a muggy night. You flash your bioluminescent signal to try to catch a lady’s attention, but how is she going to pick out your blip from all the other points of light ablaze when various species of firefly zoom around? About 1 percent of firefly species have figured out how to beat the noise: They team up and flash their lights in an unmissable, synchronous signal. And in a study in this week’s Science, researchers unlocked the inner workings of this sexual back-and-forth.
Biologists had long known about the synchronous flashing, but had not tested the idea that each species has its own rhythm—its own signal to complete the optical call-and-response between male and female.
To do this, Andrew Moiseff of the University of Connecticut in Storrs and Jonathan Copeland at the State University of New York at Stony Brook turned to LEDs. They put female synchronous fireflies (Photinus carolinus) in a Petri dish surrounded by green LEDs, and flashed the lights in the same pattern used by male fireflies. The females responded with their signature pattern 82 per cent of the time – but only if the LEDs were synchronised. When the lights did not flash in unison, female response dropped to 10 per cent or less [New Scientist].
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It doesn’t take much to be a vile, bloodsucking pest. You, human, have three billion base pairs in your genome, but the body louse—which has been a typhus-spreading scourge of humanity for millennia—carries just 108 million. That’s what scientists say today in a study in the Proceedings of the National Sciences that describes how they sequenced the body louse genome.
Because the body louse (a separate creature from the head or pubic louse) lives entirely on humans, hatching in our clothes and eating our blood, its genome can get away with being so streamlined, study author Barry Pittendrigh says:
“Most of the genes that are responsible for sensing or responding to the environment are very much reduced,” Pittendrigh said. The body louse was found to have “significantly fewer genes” for smell and taste, as well as minimal genes responsible for a “simple visual system,” the study authors wrote. They found just 10 genes to code for odor receptors [Scientific American].
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The single-mindedness that drives a swarm of locusts to rampage through the countryside and devour everything in its path might not seem like it would require a great deal of brainpower. However, biologists in Britain have found that the brain of a swarming locust swells up to 30 percent larger than the brain of its solitary counterparts.
These crazed grasshoppers aren’t geniuses, says lead researcher Swidbert Ott. According to his study forthcoming in the Proceedings of the Royal Society B, swarming locusts simply need enlarged brains to cope with the assault on their senses that comes with being caught up in an insect mob:
Locust brains are quite simple: on each side of the head is an optic lobe taking in information from the eyes and performing basic processing, and these lobes feed into the central midbrain, which carries out higher-level processing.
In swarming locusts, the midbrain grew more than the optic lobes. This, and other subtle changes, suggest that because swarming locusts are constantly surrounded by wild activity, they do not need to worry about having particularly sensitive vision. However, they do need extra high-level processing power to cope with the extremely complex patterns of motion that they see [New Scientist].
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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.
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This spring, many beekeepers across America opened their hives and found ruin within. At a time when they should have been buzzing with activity, the hives were half-empty, with most adult bees having flown off to die. A new federal survey indicates that 2010 has been the worst year so far for bee deaths. Another study suggests that pesticides might be to blame for the mass wipeout of adult honeybees.
This winter’s die-off was the continuation of a four-year trend. At any given point, beekeepers can expect to see 15 to 20 percent of their bees wiped out due to natural causes or harsh weather. But this alarming phenomenon, termed colony collapse disorder (CCD), has seen millions of bees perish in a mysterious epidemic, with some farmers losing 30 to 90 percent of their hives.
As for the cause of this epidemic, experts say their best guess is that many factors are combining to sicken bees, with the list of culprits including parasites, viruses, bacteria, poor nutrition, and pesticides. Now a new study published in the scientific journal PLoS ONE strengthens the case for pesticides’ culpability.
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A certain species of dung beetle has been crowned the world’s strongest insect. A male Onthophagus taurus can pull 1,141 times its own body weight — the equivalent of a 70-kilogramme (154-pound) person being able to lift 80 tonnes, the weight of six double-decker buses [AFP]. That power comes in handy not just to roll up a few extra dung-balls, but also to protect mates and stave off potential rivals.
Chronicling the insect’s amazing strength in the journal Proceedings of the Royal Society B, scientists Rob Knell and Leigh Simmons explain that the beetle’s amazing strength is connected to his sex life. These female dung beetles dig tunnels beneath choice pieces of dung in which to lay their eggs. If another male enters a tunnel already occupied by a rival, then the dung beetles duke it out, each male using his immense strength in an attempt to push the other out. Usually, the male that guards the tunnel repeatedly mates with the female inside.
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As if living in Hawaii weren’t a great enough life, scientists have found a kind of caterpillar there that lives the best of both worlds—in water and on land. In the Proceedings of the National Academy of Sciences, Daniel Rubinoff’s team found that 12 species in the Hawaiian moth genus Hyposmocoma are amphibious in their caterpillar stage, the first amphibious insects ever found.
While most caterpillars are terrestrial (living on land), there are a few—0.5 percent—that are aquatic. However, all of the caterpillars seen before preferred either one or the other. Even classical amphibians, like the toad, often live mainly in one environment and seldom return to the other, perhaps just to lay eggs. But the Hyposmocoma caterpillars seem to have adopted a chilled-out Hawaiian way of life, comfortable with whatever environment they might be in. “They can stay underwater for an indeterminate period of time, or out of the water,” said Rubinoff, an entomologist. “There’s no other animal that I’m aware of that can do that” [Honolulu Advertiser].
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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.
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Male animals often use their horns to fight over females, but at least one species’ females use their horns to fight over excrement.
The species, no surprise, is the dung beetle. Unlike many of the animals we usually associate with elaborate horns, antlers, or other head weaponry—in which the male has the most impressive set—dung beetle females have horns that put the male version to shame. The reason, says a new study in the Proceedings of the Royal Society B, is that females must battle one another for that precious manure. Nicola Watson and Leigh Simmons of the University of Western Australia, Perth, pitted female dung beetles (Onthophagus sagittarius) against each other in a race for dung – a valuable resource that provides nutrients for their eggs. Matched for body size, females with bigger horns managed to collect more dung and so provide better for their offspring [New Scientist].
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It always helps to have good timing. And no one seems to understand that better than the tobacco plant Nicotiana attenuata, which grows in Western United States and flowers at night [The New York Times]. Normally, the tobacco plant is pollinated by hawkmoths that visits its flowers every night. But when these hawkmoths leave eggs behind that develop into leaf-chomping caterpillars, the plant’s self-defense snaps into place and switches to flowering in the day. That attracts a different pollinator, the hummingbird.
Ecologist Danny Kessler noticed this change when he was trying to get a picture of the plant being pollinated for a study. He saw that the plant was not just flowering in the day but also that they had changed their flowers to make them more attractive to hummingbirds: they emitted less of a chemical that attracts moths; they had less sugar in the nectar, which is the way hummingbirds prefer it; and they were more tube-shaped, making them friendly to a hummingbird’s long, thin beak [ScienceNOW Daily News].
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Some parasitic wasps may be no bigger than the head of a pin, but their genetics have plenty to teach us, a new study in Science says.
A research team has sequenced the genomes of three different species of parasitic wasp. Why bother with these tiny insects? For starters, genetics is easy. Females, like humans, carry two copies of every chromosome. But males develop from unfertilized eggs, which only carry one of each. With only one copy, even recessive mutations will be easy to identify and characterize [Ars Technica].
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Researchers from the Imperial College London have a new strategy to combat malaria. The species of mosquito responsible for the spread of malaria in Africa, Anopheles gambiae, only mates once during its life. Putting a stop to their one shot at reproduction should slow down malaria transmission. Anopheles males deploy a glob of proteins and fluids known as a “mating plug” that is essential for ensuring sperm is correctly retained in the female’s sperm storage organ, from where she can fertilise eggs over the course of her lifetime [BBC News]. Without a mating plug, the sperm is not stored and the mosquitoes can’t reproduce. Simply put, the researchers want to prevent male mosquitoes from plugging in the wild.
Anopheles gambiae is the only known species of mosquito to use a mating plug. (However, mating plugs are found in other animals where they prevent multiple males from reproducing with a female. Plug checking mice in research laboratories is a right of passage for many graduate students.) In their research, written up in the journal PLoS Biology, scientists were able to alter the mosquitoes’ genes so that they could no longer form a plug, and thus were unable to reproduce. If this process could be developed for use in the field, perhaps in a spray form like an insecticide, it could “effectively induce sterility in female mosquitoes in the wild,” [study author Flaminia] Catteruccia wrote, offering potential as “one more weapon in the arsenal against malaria” [Reuters]. The WHO is optimistic that their increased funding efforts will produce more technologies similar to this one and that, hopefully, one of them will prove effective.
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Watch out next time you’re in your garden—carnivorous plants are lurking where you least expect. OK, they aren’t really dangerous, unless you’re a small insect, but now that we have your attention, scientists are reporting that common plants like petunias, potatoes, and tomatoes may actually have a carnivorous nature.
Botanist Mark Chase argues that carnivorous plants are much more widespread than previously thought, they just act in more subtle ways than the Venus flytraps and pitcher plants of the world. For instance, the cross-leaved heath (Erica tetralix) is not typically considered a carnivorous plant, but this pink flower possesses sticky, adhesive glands and dwells in poor soils. Also, while carnivorous seeds might be a strange concept, those of the shepherd’s purse (Capsella bursa-pastoris) possesses a sticky layer with chemicals that can attract, kill and digest victims [Fox News]. Chase and his colleagues argue that about 300 more plants could be fairly classified as carnivores, in addition to the roughly 650 known carnivorous plants. Of the new suspects, tobacco and tomato plants are among the most famous.
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