Japanese giant hornets can wreak havoc on a hive of Japanese honeybees, slicing off the heads of worker bees, feeding on the hive’s honey, and carrying back the larvae to feed to their own young. But the native bees do have one effective defense against the giant marauders, and it’s a battle plan that uses the bees’ one clear advantage: numbers. When a hornet scout appears, hundreds of bees instantly swarm around the invader in what’s known as a “bee ball.” In a new experiment, researchers say they’ve determined exactly how the bee ball kills.
Previously, scientists thought that the heat generated by the mass of vibrating bees killed the hornet. But in the study, published in the journal Naturwissenschaften, researchers found that temperature alone can’t do the trick. The hornets “can survive for 10 minutes at a temperature up to 47C (or 116 degrees Fahrenheit), and the temperature inside the bee balls does not rise higher than 46C” [BBC News], says lead author Fumio Sakamoto. The researchers determined that increased carbon dioxide levels inside the bee ball also plays a role.
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In a rare conservation success, a beautiful butterfly species that was headed for extinction has been brought back from the brink, thanks to careful biological observations of the insect’s life cycle. The mysterious disappearance of the Large Blue Butterfly across most of northern Europe was originally put down to its popularity among insect collectors [Telegraph]. Then biologist Jeremy Thomas spent six summers in the 1970s studying the very last colony of large blue butterflies in the United Kingdom, and determined that the butterflies were dependent on one species of red ant for their survival–and those ants were losing their habitat.
The butterflies lay their eggs on flowering thyme plants, and the hatched caterpillars fall to the ground and begin to impersonate immature red ants. They secrete chemicals and even make noises that make the red ants believe they are wayward grubs. The ants then mistakenly carry the caterpillars to their underground homes and keep looking after them even though the adopted intruders gobble ant grubs for 10 months before forming a chrysalis and flying away as adult butterflies [Reuters].
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Pest control has never looked so sweet. Scientists have found that a simple derivative of sugar can shut down the immune defenses of ravaging termites, thus leaving the insects open to attacks from bacteria and fungus. Says lead researcher Ram Sasisekharan: “When you have an immune system that is compromised, you have a variety of opportunistic infections that take over…. You give these microbes sort of a leg up to attacking more seriously” [The Scientist].
As termites cause an estimated $30 billion in crop and building damages each year, and most current methods used to combat them rely on toxins that disrupt the termites’ nervous systems. These new findings could give rise to a whole new class of safer pest-control treatments, the authors say. “We wanted something environmentally friendly, biodegradable, and [that] does not play a toxic role” [National Geographic News], says Sasisekharan.
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The mighty tortoises that roam the Galapagos Islands may not have many predators, but a new study suggests that the giant reptiles could run into serious problems due to the diminutive black salt marsh mosquito. Researchers genetically analyzed the mosquito, and found that it was not introduced recently by humans but instead arrived about 200,000 years ago. Since then the insect has evolved so much it is practically a distinct species from the mainland variety. For one thing, the insect has adapted to be able to feast on the blood of lizards, tortoises and other reptiles and not solely on mammals, as it does on the mainland [The New York Times].
That diversity of diet is what has researchers worried. If the black salt marsh mosquito picks up a disease like avian malaria or West Nile fever, it could quickly spread the disease to the Galapagos’s rare tortoises and marine iguanas. Says study coauthor Andrew Cunningham: “With tourism growing so rapidly the chance of a disease-carrying mosquito hitching a ride from the mainland on a plane is also increasing, since the number of flights grows in line with visitor numbers…. If a new disease arrives via this route, the fear is that Galapagos’ own mosquitoes would pick it up and spread it throughout the archipelago” [Telegraph].
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Scientists may finally be on their way to controlling the pesky fire ants that have invaded the American South: They’re releasing swarms of parasitic flies that first turn the ants into zombies and then decapitate them. The non-native ants are at the top of scientists’ hit lists because they cause an estimated $1 billion in damage in Texas each year. The insects swarm on circuit breakers and other electrical equipment, damaging them severely. Swarms of the stinging insects can also severely injure humans and can kill smaller animals, such as calves and pets, that stumble across nests [Los Angeles Times].
Over the past ten years, Texas agricultural researchers have begun releasing several species of phorid flies, imported for this task from the South America. The flies “dive-bomb” the fire ants and lay eggs. The maggot that hatches inside the ant eats away at the brain, and the ant starts exhibiting what some might say is zombie-like behavior…. “There is no brain left in the ant, and the ant just starts wandering aimlessly. This wandering stage goes on for about two weeks” [Fort Worth Star-Telegram], says researcher Rob Plowes. Eventually the ant’s head falls off and the mature fly emerges, ready to lay its own eggs in a new round of ants.
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Each adult Argentine ant has two chemical fragrances that send out critical messages to other ants in its colony, in what is literally a matter of life and death. Normal, still-breathing adult workers carry chemicals signaling “Dead ant — haul to burial pile” on their outer covering, proposes [entomologist] Dong-Hwan Choe…. What prevents awkward mistakes about who’s really dead are two additional compounds also found on the covering of living ants, Choe suggests. These compounds temporarily inhibit responses to the death cues by signaling, “Wait — still alive so far,” Choe and his colleagues report [Science News].
Choe’s study, which was published in the Proceedings of the National Academy of Sciences, set out to examine the corpse-ridding behavior, or necrophoresis, that is common to many ants and other social insects, and helps maintain good sanitation in the colony…. The prevailing theory of necrophoresis had been that ants were responding to fatty acids and other chemical cues from the decomposing corpse. But the researchers noticed that ants would haul a corpse away within an hour after death — before much decomposition began [The New York Times].
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Males of the spider species Harpactea sadistica have a violent way of increasing their odds of reproductive success. In the midst of a mating tussle, the male stabs his spiked copulatory organ (pictured) into the abdomen of the female, in order to deposit his sperm directly into the female’s ovaries.
This process, known as traumatic insemination, is common among many hermaphrodite species as well as some insects with separate sexes, most famously the bed bug. But it has never before been observed in other arthropods. “Now we have a very odd biological phenomenon in an unrelated taxonomic group…. It’s like finding a peacock’s tail in a non-bird species” [The Scientist], says Mike Siva-Jothy, who has observed the behavior in bed bugs.
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Scientists have managed to make extra-strength spider silk—already notable for having a tensile strength higher than many alloys of steel, even though its comprised entirely of proteins [Ars Technica]—by incorporating small amounts of metal into it. A research team at the Max Planck Institute was inspired by studies showing traces of metals in the toughest parts of some insect body parts. The jaws of leaf-cutter ants and locusts, for example, both contain high levels of zinc, making them particularly stiff and hard [Reuters]. The researchers wanted to try adding metals into existing biological materials, and decided to start with the Araneus spider.
The researchers, whose work is published in Science, used atomic-layer deposition to pulse zinc, titanium, and aluminum ions into spider silk [Technology Review]. The process is used normally to apply a thin film layer of one material onto another, but the researchers found that the metal ions had actually penetrated and reacted with the protein structure of the silk, yielding a material significantly stronger than natural spider silk, though they don’t quite understand how the integration occurred. One of the researchers, Mato Knez, attributes the strengthening effect to the metal’s displacement of hydrogen bonds within the silk’s protein structure…. The team were also able to show that the outer metal coating of the silk was of minor importance in the improvement of strength, and therefore that the phenomena was caused by the metals imbedded in the protein fibres [Chemistry World].
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In the latest development in the ongoing debate about why some leaves turn bright red in the fall, a new study suggests that the color is a signal to insect pests to stay away. Harvard biologist Marco Archetti sought to prove the theory, first put forth in 2001 by the late evolutionary biologist William Hamilton, that the red pigments, or anthocyanins, serve as a plant’s chemical defense. Archetti studied aphids’ survival rates in wild apple trees, which turn more red, compared with farmed trees, which produce more green and yellow leaves. He found that aphids don’t show up as frequently on apple trees that turn red in the fall [ScienceNews]. He also reports in the study, published in Proceedings of the Royal Society B, that once spring came, young aphids who had fed on red trees in the fall were less likely to grow to maturity than aphids placed in the green or yellow trees.
Archetti chose aphids for the study because fall is their mating season: They leave their summer plants to find a good tree for mating and egg laying. Aphids can damage trees in two ways, especially when the new generation hatches in the spring. The insects steal the sap and also spread diseases with their piercing mouthparts that end up as entomological dirty needles. So trees would do well to dodge aphids [ScienceNews]. To test whether the red signals a threat to the insects, Archetti placed nesting aphids in both red- and green-leaved apple trees in the fall of 2007, and found that the next spring, 60 percent of those in green trees had survived, compared with 29 percent in red trees. The reason behind this disparity is unclear, but Archetti’s and other studies suggest that the red leaves either have toxic chemical defenses or hold fewer nutrients for young aphids [ScienceNow Daily News].
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Researchers have learned the universal secret behind the graceful, aerial turns executed by everything from insects to cockatoos. And it’s a surprisingly simple process: To turn left, all a bird has to do is flap its right wing a little bit harder than the left wing. To end the turn, the bird simply returns to flapping its wings in unison [Discovery News]. Researchers hope to duplicate the simple set of motions to create more nimble and acrobatic flying robots.
Though the dynamics probably can’t work at large scales — building-sized robotic birds won’t ever be as agile as a swallow — they could be harnessed in small drones used by explorers or the military. Compared to the average hummingbird or fruit fly, such craft are now clumsy and unstable. “The results will inform all future research into maneuvering flight in animals and biomimetic flying robots” [Wired], wrote biomechanicist Bret Tobalske in a commentary.
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Bed bugs are a nuisance that is on the rise around the world, but the bugs don’t spread disease, according to new research. Because they feed on blood, there was a concern that the pests transmitted diseases like HIV and hepatitis, but it now seems that they don’t pose a health threat.
Led by entomologist Jerome Goddard, the study showed no sign of disease transmission by the bugs; it did confirm, however, the bugs’ increased resistance to insecticides and the lack of alternative methods to eradicate infestations, as well as the lack of effective treatment options for troublesome bites. Many people don’t even know they’ve been bitten: 7 in 10 people see no signs apart from an almost invisible puncture mark on their skin. When people do get a reaction, it usually takes the form of red, itchy patches a few millimetres across, each one the result of an individual bite [The Guardian]. Allergic reaction is also possible, but rare, and any rash that results will disappear on most people within a week, although scratching can prolong the symptoms.
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While the Eurythmics and Aretha Franklin were singing about female empowerment in the human species, they’d probably approve of this termite queen’s activities. When it comes time for aging queens of the Japanese species Reticulitermes speratus to produce replacement queens, they don’t bother to mate with their king and instead produce their daughters asexually, in a process called parthenogenesis. Even when the queen dies, she maintains her genetic contribution to the colony. “This gives genetic momentum to the expression ‘Long live the queen’” [ScienceNOW Daily News], comments entomologist Barbara Thorne.
A termite colony starts when a king and queen pair up during an annual mating flight and settle down to start a family. At first, the couple produces worker and soldier termites that care for the nest. When the colony gets big enough, the king and queen start making alates–winged termites that leave home to find mates and start colonies of their own [ScienceNOW Daily News]. Finally, towards the end of her life, the queen has to produce several replacement queens to keep the colony going. In most species the king and queen mate to conceive these secondary queens, but that poses a problem before too long, when the king begins to mate with his daughters. This termite incest creates a next generation with reduced genetic diversity.
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The blast that shook the Chernobyl nuclear power plant more than 20 years ago, sending a highly radioactive plume of fallout into the air, still affects local populations of butterflies and bees and other insects, according to a new study. The study appears to argue against the idea put forward by previous researchers that the region around the power plant, contaminated by radiation and off limits to most humans, has become a sort of post-apocalyptic Eden [The New York Times], in which animals can live unmolested. However, the new results are stirring up controversy.
A pair of researchers conducted standard surveys in forests around Chernobyl over three springs from 2006 to 2008, noting the numbers of bumblebees, butterflies, grasshoppers, dragonflies and spider webs at points with radiation levels that varied over four orders of magnitude [The New York Times]. They found that the number of bugs declined as the radiation increased, and that even relatively low levels of radiation impacted insect populations. The researchers say insects may be particularly vulnerable because radiation is usually found in the top layer of soil, where many invertebrates spend time during either their egg, larvae, or adult phases.
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If aphids could recite Shakespeare, they might favor this rousing cry: “Once more unto the breach, dear friends, once more; or close the wall up with our [aphid] dead.” Researchers have discovered that the social insects send soldiers to repair holes in the plant tissue where they make their homes, and that some of the soldiers never return from these “suicide missions.”
Some aphids cause their plant hosts to form hollow swellings called galls within which the larvae mature. A hole in the gall’s wall threatens the larvae’s cozy and protected home, and causes soldier aphids to rush to the spot. There they excrete body fluids that represent about two-thirds of their body mass, and mix the fluids with their legs to form a scab that patches the hole. Many of the soldier aphids, of the species Nipponaphis monzeni, die from the significant loss of body mass. Many others get stuck in the viscous fluid and fail to escape. Like workers on the Great Wall of China, they simply become a physical part of the building work [BBC News].
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In a classic tale of symbiosis, researchers have determined that a parasitic wasp got its most potent weapon from an ancient virus that may have attacked it around 100 million years ago.
When a parasitic wasp wants to lay its eggs in a caterpillar, it takes steps to ensure that everything goes according to plan: Along with the eggs, it injects a powerful dose of virus-like particles. Not only do these disable the caterpillars’ immune system to stop it attacking the eggs, they also cause paralysis and keep the host from pupating – turning the caterpillar into an eternally youthful larder and nursery for the wasp grubs [New Scientist]. But the nature of the wasp’s poison has been a subject of debate.
The virulent particles, were named polydnaviruses because they resemble viruses; they consist of protein-encased, double-stranded DNA pieces. But their DNA doesn’t match that of any other known virus, and a closer analysis showed that the particles contained mostly wasp DNA. That had entomologists wondering if the wasps had come up with the virus-imitating particles themselves. “The spectre arose that the wasps were doing really clever genetic engineering that looks just like a virus but is really a wasp invention” [New Scientist], explains lead researcher James Whitfield.
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