'Zen' Bats Hit Their Target by Not Aiming at It

(Feb. 5, 2010) — New research conducted at the University of Maryland's bat lab shows Egyptian fruit bats find a target by NOT aiming their guiding sonar directly at it. Instead, they alternately point the sound beam to either side of the target. The new findings by researchers from Maryland and the Weizmann Institute of Science in Israel suggest that this strategy optimizes the bats' ability to pinpoint the location of a target, but also makes it harder for them to detect a target in the first place.

Researchers have found that a type of fruit bat finds its target by NOT aiming their guiding sonar directly at it. Instead, it alternately point the sound beam to either side of the target.

"We think that this tradeoff between detecting a object and determining its location is fundamental to any process that involves tracking an object whether done by a bat, a dog or a human, and whether accomplished through hearing, smell or sight," said coauthor Cynthia Moss, a University of Maryland professor of psychology, who directs interdisciplinary bat echolocation research in the university's Auditory Neuroethology Lab, better known as the bat lab.

Moss, colleagues Nachum Ulanovsky and Yossi Yovel of the Weizmann Institute, and Ben Falk, a graduate student of Moss's in Maryland's Neuroscience and Cognitive Science Program, published their findings in the journal Science. Ulanovsky, the paper's corresponding author, was a Maryland postdoctoral student under Moss.

For this research, Ulanovsky and Yossi trained fruit bats to land on a spherical target while relying exclusively on their sonar. Trained in Israel, the bats were then brought to Maryland to be studied in Moss's specialized lab. High speed infrared cameras recorded the bats movement in flight while the shape and direction of their sonar beam patterns was measured with a sensitive arrangement of 20 microphones positioned around the large room. These bats emit paired clicking sounds and the researchers found that the sonar beam created by each click alternated to the left and right of a target. This alternating pattern effectively directed the inside edge, or maximum slope, of each sonar beam onto the target. As a result, any change in the relative position of the target to the bat reflected that large sonar edge back at the bat, delivering the largest possible change in echo intensity.

However, as the researchers note, there is a cost to this approach: less sound is reflected back to the bat from the object than if the sound beam were aimed more directly toward the object. Thus the fruit bat's strategy of using the steepest edge of a sonar beam (which intuitively follows a mathematical optimization formula) sacrifices a little target-detection for pinpoint accuracy in tracking.

Detecting vs. Tracking

By changing the conditions of their experiments in the bat lab the researchers were able to show that the fruit bats will sometimes change their echolocation strategy based on the situation. To do this, a reflecting board was positioned behind the target, creating "noise" echoes that competed with those from the target, potentially making detection of the target more difficult. In trials under these conditions, some bats altered their sound beam directional strategy. These bats started off with the wide side to side pointing that maximizes determining location, but once they got closer, switched to point the beams from both clicks almost directly at the target.
Moss, who has been researching bat echolocation for 20 years, notes that even among different bat species there are different approaches to tracking objects. Much of the research she and her students have conducted in the bat lab has looked at big brown bats, which are common in the United States. Big brown bars generate sound with their vocal cords and aim the resulting sound beam directly at their targets, an approach that maximizes their ability to detect the mosquitoes and other small, fast moving insects that serve as food.

"The difference in sonar beam directing strategies between the Egyptian Fruit bats and Big Brown bats may be related to the differences between their sound production mechanisms (tongue clicks vs. vocalizations), echo processing systems, behavioral requirements in nature, or other species differences," said Moss, a former director of the Neuroscience and Cognitive Science Program, who also holds an appointment in the university's Institute for Systems Research.
The researchers suggest other animals reflect similar approaches to the detection versus tracking tradeoff. Their paper gives the example of a hound dog following an odor trail using a similar localization approach to that used by the tongue clicking Egyptian fruit bats.

"People without sight use echolocation, in some cases also generating sound by tongue clicking," said Moss. One such person, she noted, is Daniel Kish, Executive Director of World Access for the Blind. Totally blind from birth, Kish uses tongue clicking for sonar that allows him to "see" his enviroment at a very high level, even allowing him to safely ride a bike in a city street. Kish is "the first totally blind, national certified Orientation & Mobility Specialist," according to the website for World Access for the Blind. Check out this YouTube video about Kish and his work educating others to use echolocation.

"There are no measurements of the directionality of the sound beams used by blind echolocators like Kish," Moss said. "But looking at head movements in echo locating blind individuals, it seems that some may show a similar strategy [to that of fruit bats]."

New Primitive Dinosaur Used Claws to Hunt Termites

Sometime in 2004, the Xinjiang Autonomous Region in China provided experts with the fossilized remains of a dinosaur that could not be cataloged. At that time, experts who had seen it had proposed that the creature was part of a new species, and their predictions eventually turned out to be true. The animal was named Haplocheirus sollers (“simple, skillful hand”), and its major traits were subject to rigorous analysis. As this was done, experts learned a great deal about this small lizard.

For one, its body was covered in feathers, but its teeth were long and serrated. According to the investigators, it may be that the animals also used their claws to basically hunt termites out of their nests, which would make it one of the first animals ever to do so. The fossil, which endured for more than 160 million years, is believed to have belonged to an individual that was at least 7 feet long (2 meters) and weighed roughly 33 pounds (15 kg). The team investigating these bones also concluded that the creature was a member of the peculiar-looking, feathered dinosaur group Alvarezsauridae.

George Washington University investigator Jonah Choiniere, who was a researcher on the new study, says that the earliest proof that Alvarezsauridae existed came from fossils that were “only” 85 million years old. One of the defining traits for these animals was their short, stubby arms, and also the fact that they only had a single large claw on their hands, flanked by several that were considerably smaller “Haplocheirus is a transitional fossil, because it shows an early evolutionary step in how the bizarre hands of later alvarezsaurs evolved from earlier predatory dinosaurs,” Choiniere explains, quoted by LiveScience.

It is additionally believed that these animals were proficient termite eaters. One of the things that lead scientists to believe that is the shape and size of the animals' teeth, which seem very similar to those of modern anteaters. “When the alvarezsauroids were initially discovered only about 15 years ago the prevailing hypothesis was that they were birds – a lineage within birds that had lost flight ability. And so what Haplocheirus shows is really that alvarezsauroids are not birds, but it pushes them further down the evolutionary tree,” the expert concludes.

Rats In Plumbing Cause Home Damage

Large rodents are causing high-dollar damage to homes. Three times in the month of December, rats chewed through three different water pipes in Lois Stevenson’s Yuba City home.

“Never in my wildest dreams would I have known that rats where, like, in my attic having a great time,” said Lois Stevenson.

Stevenson said she had major water leaks in the ceilings and walls of her home. The damage was so extensive Stevenson had to stay in a hotel while her home was fixed.

The problem is not isolated to her house.

“I have seen them chew through the black PVC drain line,” said Sarah McNelly, with Rainbow International Restoration and Cleaning service.

This winter, McNelly said she has had four times the number of phone calls about water damage from rats chewing through pipes. According to McNelly, wet weather is forcing rats out of their homes and into yours.

“The shelter they typical find is an attic. They are not bothered by people up there and there is a ready water source for them,” McNelly said.

Repairs for this kind of damage usually runs into the thousands. At the Stevenson home in Yuba City, it has taken more than a month for repairs to be made and for life to get back to normal.

Stevenson said she hopes she won’t have this problem again.

“I have not had any problems since we caught the little sucker,” Stevenson said with a smile.

Tobacco Plant Thwarts Caterpillar Onslaught by Opening Flowers in the Morning

(Jan. 25, 2010) — Butterflies and moths are welcome visitors to many plant species. Plants attract insect pollinators with the colors, forms, nectars and scents of their flowers to ensure fertilization and reproduction. However, female moths are also threatening to the plant: Once attracted by the flower's scent, they lay their eggs on the green leaves, and shortly voracious young caterpillars hatch. Scientists from the Max Planck Institute for Chemical Ecology have now discovered how tobacco plants successfully solve this dilemma.

Wild tobacco (Nicotiana attenuata), native in North America, is flowering during the nighttime and attracts night-active moths as pollinators by emitting the attractant benzyl acetone. However, as soon as female moths start laying their eggs on the plant and the young caterpillars become a serious danger, the plant postpones the opening time of the flowers by 12 hours to dawn and additionally stops producing benzyl acetone. Moths stay away and hummingbirds take over pollination. (Credit: Danny Kessler, Max Planck Institute for Chemical Ecology, Jena, Germany)


The researchers found that herbivory changed the opening time of the flower buds from dusk to dawn. In addition the emission of flower scents was dramatically reduced. This change in flower timing was elicited by specific molecules in the oral secretions of the larvae, and required the jasmonate signaling cascade, which is known to elicit a host of other defense responses in plants. Instead of night-active moths, these morning-opening flowers attract day-active hummingbirds which are also able to transfer pollen -- without threatening the plant's life.

Outbreak of tomato hornworms

During field experiments performed by PhD students of the Department of Molecular Ecology headed by Prof. Ian T. Baldwin in the Great Basin Desert of Utah (USA) in summer 2007, a massive outbreak of tomato hornworms (Manduca quinquemaculata) occurred. Almost every tobacco plant of the native species Nicotiana attenuata on the field site was attacked by these herbivores which prefer plants of the nightshade family. Danny Kessler intensively studied the infested plants and noticed that these plants had many flowers that opened after sunrise -- although tobacco is typically a night-flowering plant and usually opens its flower buds after sunset. This finding resulted in experiments conducted in the following two years that showed that the flowering time postponed by 12 hours was directly related to herbivory.

Pollination wanted, but no oviposition

Ecologists had already noticed that female moths attracted for pollination laid their eggs, and shortly leaf-eating larvae hatched to feed on the same plant. The scientists considered whether plants would actually submit without reserve to this life-threatening disadvantage -- just for pollination. They intensively studied the remarkable morning-opening flowers (MoF) which were only produced by plants that had been attacked by insect larvae and compared them to the usually occurring night-opening flowers (NoF). The first experiment already revealed an astounding result: MoF did not emit the attractant benzyl acetone anymore (see also Kessler et al., Science 321, 2008) and also the sugar concentration in the floral nectar was considerably reduced. Furthermore, it was striking that the petals of MoF only opened to a third of the size of NoF. All in all, the MoF were rendered literally unnoticeable by the moths -- however, they may become interesting for different pollinators living nearby the field station: hummingbirds.

Hummingbirds visit the morning-opening flowers and serve as pollinators

To find out whether moths or birds successfully transferred pollen from flower to flower, the scientists determined the outcrossing rate of plants visited by moths or hummingbirds in field experiments. They removed the anthers from young flower buds to rule out self-pollination. Then an unattacked and an insect-attacked tobacco plant were covered with a mesh-covered wire cage until the morning of the next day to exclude night-active pollinators. A second pair of plants remained uncovered and thereby accessible to night-active pollinators. Before dawn the cages were exchanged, so that the plants that had been uncovered during the night were now covered and the plants that had been covered at night became accessible to pollinators during the day. In the evening all experimental plants were covered and the plants remained so until seed capsules were produced. Counting of the capsules revealed that a significant majority of capsules on plants that had not been attacked by caterpillars originated from flowers that were pollinated during the night between 8:00 p.m. and 6:00 a.m., whereas in caterpillar-infested plants successful pollination had occurred in majority during the day between 6:00 a.m. and 8:00 p.m., therefore by hummingbirds.

The scientists verified the assumption that actually hummingbirds visit the MoFs and drink their nectar by directly observing and counting out more than 1000 flowering wild tobacco plants. 18 humming bird visitations were intensively studied which showed hummingbirds visiting larvae-infested plants. As a matter of fact, more than 90% of the birds preferred the MoF compared to NoF, even if only a few MoF were on a plant. "It is likely that the hummingbirds can recognize the special shape of the partially open corollas of the MoF in the morning and associate these characteristics with the reliable quality and quantity of the nectar in these flowers," says Celia Diezel, co-author of the study.

Experiments using larval oral secretions and transgenic tobacco plants

In further experiments the scientists studied how attacked plants recognize herbivory and subsequently change the developmental program of the flowers to favor hummingbirds. Instead of infesting the plant by putting caterpillars on the leaves, the researchers mechanically wounded a leaf with a pattern wheel and applied oral secretions from hornworm larvae on the wounds. The plant reacted as after direct insect attack: After approximately 3 days more morning-opening flowers compared to non-induced plants were produced.

"Maybe the fatty acid amino acid conjugates present in the oral secretions of the larvae elicit this reaction. We already know that they switch on the plant's defense against herbivory, for instance by producing toxic substances to fend off the attacker," Danny Kessler, PhD student at the institute, explains. In an additional experiment he used genetically modified tobacco, in which the signaling pathway between the messenger molecule in the oral secretion and the defense reaction was interrupted; these plants were unable to produce jasmonate, a plant hormone initiating plant defense responses. In fact, the transgenic jasmonate-deficient plants used in the field experiment did not produce MoF after spit induction, but could if the plants were sprayed with jasmonate, which showed that the reprogramming of the flower production is actually related to the pathway that switches on defense mechanisms.

Why do plants risk attracting tomato hornworm moths as pollinators, although the insects' larvae feed on the plants? "We cannot answer this question from the perspective of one single plant, but, if at all, from an evolutionary and ecological background," says Ian Baldwin.

Wild tobacco populations grow on vast areas after fires, comparable to synchronized monocultures with thousands of widespread plants. Hummingbirds may not be the most reliable pollination service the plant species needs for outcrossing and reproduction. Using volatiles, the plants can attract moths from large distances, whereas hummingbirds are only available, if their nests are accidentally in the vicinity of the tobacco populations. Moreover, looking at the special mode of hummingbird pollination, it is more likely that flowers of one single plant are pollinated with pollen from the same plant than from flowers of different plants. This can decrease the genetic variability of the seeds produced. Moths may move more frequently among plants and this behavior may results in greater genetic variability for the seed produced from their pollination services. [JWK/AO]

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Why Mice Develop 'Knots' While Exploring a New Environment

(Jan. 18, 2010) — During exploration of a new environment, mice establish "knots" -- preferred places visited sporadically and marked by the performance of twists and turns, according to a new study by Israel and Canada-based researchers. The research provides evidence that the formation of these places is increased by stress, and suggests that the tortuous movements improve the interpretation of the visual scene, enhance the memory of the place and provide the mouse with multiple views that turn the established places into navigational landmarks.

Details are published January 15 in the open-access journal PLoS Computational Biology.
The notion of "a place" and an "itinerary" is taken for granted in everyday life but how these abstract ideas are created is a subject of much discussion and research. Using advanced computational tools the authors show how a particular type of place (knot) is formed and then used by mice. The knots, and other preferred places discovered earlier, contribute to our understanding of how the animals map the environment, and what they try to accomplish.
In an empty arena devoid of proximal cues, the rich perceptual inputs generated by the twisting and turning could improve the mouse's view of the environment and more generally enhance or even embody for the mouse the memory and significance of this place by tagging it with a place-specific perceptual signature, say the authors.
Exploration is a central component of human and animal behavior that has been studied in rodents for almost a century. It is presently one of the main models for studying the interface between behavior, genetics, drugs, and the brain. Until recently, rodents' exploration of an open field has been considered to be largely random. Lately, this behavior is being gradually deciphered, revealing reference places established and used by the animals for navigation.
Portrayal of how behavior is structured within and around knots in normal animals can later be used to study how this behavior is affected by pharmacological and genetic manipulations.

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Sex Life May Hold Key To Honeybee Survival

 (Jan. 11, 2010) — The number and diversity of male partners a queen honeybee has could help to protect her children from disease, say University of Leeds scientists, who are investigating possible causes of the widespread increase in bee deaths seen around the world.
The researchers are working on the theory that the reason some colonies are wiped out while others remain healthy could be down the genetic diversities of the hives.

Dr Bill Hughes, from the Faculty of Biological Sciences at the University of Leeds, says: “By making sure queens mate with enough genetically variable males, we may be able to boost resistance levels and so protect our Bee populations from disease attacks like the ones we have seen hitting the US.”

One possibility is that the loss of honeybees means that the number and variety of potential mates for a queen is becoming too low to maintain genetic diversity and therefore disease resistant populations.

Says Dr Hughes: “Given the choice, queen honeybees will typically mate with up to 12 different male partners in a matter of minutes and some with over 20. The record is the giant Asian honeybee whose queens normally mate with well over 40 males - and in one case was found to have mated with over a hundred.”

The Leeds scientists will be examining the question of genetic resistance by studying honeybee reactions to a common fungus parasite called Chalkbrood, under carefully controlled laboratory conditions.

The fungus, already found in the majority of UK hives, infects and ‘eats’ larvae, giving them a chalky appearance. Individual larvae die but the parasite rarely kills the whole colony.

In 2008, US average losses of honeybee colonies were 35%, with some beekeepers losing 90% of their colonies. A contributing factor to these high levels of bee may have been a virus. However the same virus has been found in other countries yet does not seem to cause the same problems.

Dr Hughes and his team think infections by hidden parasites in genetically susceptible bees may be combining with other factors to produce a lethal ‘perfect storm’ which overwhelms their defences.

Honeybee survival is vital to the protection of our food supplies because they pollinate up to a third of the food we grow in the UK.

The project, which has received just under £500,000 in funding from the Natural Environment Research Council, is due last for three years. Collaborators include the UK Government’s National Bee Unit based near York and the University of Copenhagen.

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To a Mosquito, Matchmaking Means 'Singing' in Perfect Harmony

 (Jan. 4, 2010) — Researchers have new insight into the sex lives of the much-maligned mosquitoes that are responsible for the vast majority of malaria deaths, according to a report published online on December 31st in Current Biology, a Cell Press publication.
                                                                                 A new study shows that in finding a partner of the right species type, male and female mosquitoes depend on their ability to "sing" in perfect harmony.
In finding a partner of the right species type, male and female mosquitoes depend on their ability to "sing" in perfect harmony. Those tones are produced and varied based on the frequency of their wing beats in flight.
"Everyone must be familiar with the maddening whine a mosquito makes as it hones in for a bite," said Gabriella Gibson of the University of Greenwich at Medway. "There's no doubt many of us have wondered why it makes its presence so obvious -- surely, after all of these centuries of blood-feeding, selection should have favored a more stealthy approach that would leave mosquitoes less vulnerable to the defensive attacks of its unsettled host. Our findings suggest that mosquitoes rely on the sounds they make to attract a mate of the right species, a behavior that is far more vulnerable to selection than avoiding the risk of being squashed by the rare host that is still awake at feeding time."

The Anopheles gambiae mosquitoes in fact include a considerable amount of genetic diversity, representing a complex of seven species and several chromosomal forms. And that diversity comes with real consequences for humans, explained Gibson and Ian Russell of the University of Sussex. The complexity of malaria epidemiology and control is due in part to the mosquito's remarkable genetic plasticity, enabling its adaptation to a widening range of human-influenced habitats.
The new results help to explain how those different mosquito forms manage to reproductively isolate themselves and maintain that genetic diversity, even while some, including the "M" and "S" forms found in Burkina Faso that were the subject of the current study, can be found traveling together in the very same swarms.
Gibson and Russell's team first discovered that male and female mosquitoes harmonize with each other. Gibson said that this is analogous to two partially deaf singers -- one alto and the other soprano -- who can hear low frequencies, but perhaps not their own or each other's songs. Instead, they listen to the terrible dissonance if one or the other goes a bit sharp or flat, which they can get rid of by adjusting their respective tones until the dissonance diminishes to nothing.

"They can do this even if they each sing a different note, say a 'middle C' and a 'G' four tones higher," Russell said. "By listening and subtly altering their pitch to minimize the dissonance, they achieve their goal of 'singing' in a perfect harmony that we, but not they, can hear."
The researchers have now shown that two mosquitoes don't harmonize successfully if they are of the same sex or if they are not the same type of mosquito. They might try for a while, Gibson explained, but they never find that harmony and eventually give up trying.
And that leads Gibson to another take-home of the study. "Even the most 'lowly creatures,' such as mosquitoes, have highly evolved neurosensory systems that can process relatively simple auditory inputs to produce motor outputs enabling them to distinguish between other types of mosquito that are so closely related we need to analyze their DNA to tell them apart."

The researchers include C. Pennetier, University of Sussex, U.K., University of Greenwich at Medway, Kent, U.K., B. Warren, University of Sussex, U.K.; R. Dabire, Institut de Recherche en Science de la Sante/Centre Muraz, Burkina Faso; I.J. Russell, University of Sussex, U.K.; and G. Gibson, University of Sussex, U.K., University of Greenwich at Medway, Kent, U.K.

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Final Moments of Bee Landing Tactics Revealed

(Jan. 2, 2010) — Landing is tricky: hit the ground too fast and you will crash and burn; too slow and you may stall and fall. Bees manage their approach by monitoring the speed of images moving across their eyes. By slowing so that the speed of the looming landing pad's image on the retina remains constant, bees manage to control their approach. But what happens in the final few moments before touch down? And how do bees adapt to landing on surfaces ranging from the horizontal to upside-down ceilings?

Bees manage their approach by monitoring the speed of images moving across their eyes. By slowing so that the speed of the looming landing pad's image on the retina remains constant, bees manage to control their approach. (Credit: iStockphoto/Amit Erez)

Flies land on a ceiling by simply grabbing hold with their front legs and somersaulting up as they zip along, but a bee's approach is more sedate. Mandyam Srinivasan, an electrical engineer from the Queensland Brain Institute, The University of Queensland and the Australian Research Council's Vision Centre, knew that bees must be doing something different from daredevil flies. Curious to know more about bee landing strategies Srinivasan teamed up with Carla Evangelista, Peter Kraft, and Judith Reinhard from the University of Queensland, and Marie Dacke, visiting from Lund University.

The team used a high-speed camera to film the instant of touch down on surfaces at various inclinations and publish their discoveries about bee landing tactics in The Journal of Experimental Biology on December 28 2009 at http://jeb.biologists.org/.
First the scientists built a bee-landing platform that could be inclined at any angle from horizontal to inverted (like a ceiling), then they trained bees to land on it and began filming. Having collected movies of the bees landing on surfaces ranging from 0deg. to 180deg., and every 10deg. inclination between, Evangelista began the painstaking task of manually analysing the bees landing strategies, and saw that the bees' approach could be broken down into 3 phases.
Initially the bees approached from almost any direction and at any speed, however, as they got closer to the platforms, they slowed dramatically, almost hovering, until they were 16mm from the platform when they ground to a complete halt, hovering for anything ranging from 50ms to over 140ms. When the surface was horizontal or inclined slightly, the bees' hind legs were almost within touching distance of the surface, so it was simply a matter of the bee gently lowering itself and grabbing hold with its rear feet before lowering the rest of the body.

However, when the insects were landing on surfaces ranging from vertical to 'ceilings', their antennae were closest to the surface during the hover phase. The team saw that the antennae grazed the surface and this contact triggered the bees to reach up with the front legs, grasp hold of the surface and then slowly heave their middle and hind legs up too. 'We had not expected the antennae to play a role and the fact that there is a mechanical aspect of this is something that we hadn't thought about,' admits Srinivasan.

Looking at the antennae's positions, the team realised that in the final stages as the insects approached inverted surfaces, they held their antennae roughly perpendicular to the surface. 'The bee is able to estimate the slope of the surface to orient correctly the antennae, so it is using its visual system,' explains Srinivasan. But this is surprising, because the insects are almost completely stationary while hovering and unable to use image movement across the eye to estimate distances. Srinivasan suspects that the bees could be using stereovision over such a short distance, and is keen to test the idea.
Finally the team realised that bees are almost tailor made to land on surfaces inclined at angles of 60deg. to the horizontal. 'When bees are flying fast their bodies are horizontal, but when they are flying slowly or hovering their abdomen tilts down so that the tips of the legs and antennae lie in a plane that makes an angle of 60deg.' explains Srinivasan: so the legs and antennae all touch down simultaneously on surfaces inclined at 60deg. 'It seems like they are adapted to land on surfaces tilted to 60deg. and we are keen to find out whether many flowers have this natural tilt,' says Srinivasan.
Srinivasan is optimistic that he will eventually be able to use his discoveries in the design of novel flight control systems.

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Dominant Chemical That Attracts Mosquitoes To Humans Identified

(Dec. 30, 2009) — Scientists at the University of California, Davis, have identified the dominant odor naturally produced in humans and birds that attracts the blood-feeding Culex mosquitoes, which transmit West Nile virus and other life-threatening diseases.

The groundbreaking research, published this week in the early online edition of the Proceedings of the A side view of a Culex mosquito, an important vector in West Nile Virus transmission.

National Academy of Sciences, explains why mosquitoes shifted hosts from birds to humans and paves the way for key developments in mosquito and disease control.

Entomology professor Walter Leal and postdoctoral researcher Zain Syed found that nonanal (sounds like NAWN-uh-nawl) is the powerful semiochemical that triggers the mosquitoes' keen sense of smell, directing them toward a blood meal. A semiochemical is a chemical substance or mixture that carries a message.
"Nonanal is how they find us," Leal said. "The antennae of the Culex quinquefasciatus are highly developed to detect even extremely low concentrations of nonanal." Mosquitoes detect smells with the olfactory receptor neurons of their antennae.
Birds, the main hosts of mosquitoes, serve as the reservoir for the West Nile virus, Leal said. When infected mosquitoes take a blood meal, they transmit the virus to their hosts, which include birds, humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels and domestic rabbits. Since 1999, the U.S. Centers for Disease Control and Prevention have recorded 29,397 human cases and 1,147 fatalities in the United States alone.
The UC Davis researchers tested hundreds of naturally occurring compounds emitted by people and birds. They collected chemical odors from 16 adult human subjects, representing multiple races and ethnic groups.
"We then determined the specificity and sensitivity of the olfactory receptor neurons to the isolated compounds on the antennae of the mosquitoes," Syed said.
Leal and Syed found that nonanal acts synergistically with carbon dioxide, a known mosquito attractant. "We baited mosquito traps with a combination of nonanal and carbon dioxide and we were drawing in as many as 2,000 a night in Yolo County, near Davis," Syed said. "Nonanal, in combination with carbon dioxide, increased trap captures by more than 50 percent, compared to traps baited with carbon dioxide alone."
The UC Davis research was funded in part by the National Institutes of Health; a cooperative research agreement with Bedoukian Research, a supplier of specialty aroma and flavor ingredients headquartered in Connecticut; and the National Science Foundation.

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Cockroaches Offer Inspiration for Running Robots

(Dec. 29, 2009) — The sight of a cockroach scurrying for cover may be nauseating, but the insect is also a biological and engineering marvel, and is providing researchers at Oregon State University with what they call "bioinspiration" in a quest to build the world's first legged robot that is capable of running effortlessly over rough terrain.

Researchers at Oregon State University are using studies of guinea hens and other animals such as cockroaches to learn more about the mechanics of their running ability, with the goal of developing robots that can run easily over rough terrain. (Credit: Image courtesy of Oregon State University)
If the engineers succeed, they may owe their success to what's being learned from these insects and other animals, such as the guinea hen, that have their own remarkable abilities.
The latest findings -- just published in the professional journal Bioinspiration and Biomimetics -- outline how animals use their legs to manage energy storage and expenditure, and why this is so important for running stability. The work is being supported by the National Science Foundation.
"Humans can run, but frankly our capabilities are nothing compared to what insects and some other animals can do," said John Schmitt, an assistant professor in the School of Mechanical, Industrial and Manufacturing Engineering at OSU. "Cockroaches are incredible. They can run fast, turn on a dime, move easily over rough terrain, and react to perturbations faster than a nerve impulse can travel."
Within certain limitations, Schmitt said, cockroaches don't even have to think about running -- they just do it, with muscle action that is instinctive and doesn't require reflex control. That, in fact, is part of what the engineers are trying to achieve. Right now some robots have been built that can walk, but none of them can run as well as their animal counterparts. Even walking robots absorb far too much energy and computing power to be very useful.
"If we ever develop robots that can really run over rough ground, they can't afford to use so much of their computing abilities and energy demand to accomplish it," Schmitt said. "A cockroach doesn't think much about running, it just runs. And it only slows down about 20 percent when going over blocks that are three times higher than its hips. That's just remarkable, and an indication that their stability has to do with how they are built, rather than how they react."
If successful, Schmitt said, running robots could serve valuable roles in difficult jobs, such as military operations, law enforcement or space exploration. Related technology might also be applied to improve the function of prosthetic limbs for amputees, or serve other needs.
The OSU researchers are trying to identify some of the basic biological and mechanical principles that allow certain animals to run so well and effortlessly. A guinea hen, for instance, can change the length and angle of its spring-like legs to almost automatically adjust to an unexpected change in a ground surface as much as 40 percent of its hip height. That would be like a human running at full speed, stepping into a 16-inch-deep hole and never missing a beat.
Researchers are getting closer to their goal.
In a computer model, they've created a concept that would allow a running robot to recover from a change in ground surface almost as well as a guinea hen. They are studying how the interplay of concepts such as energy storage and expenditure, sensor and feedback requirements, and leg angles can produce recovery from such perturbations. Ultimately, a team of OSU engineers hopes to use knowledge such as this to actually build robots that can efficiently run over rough terrain without using significant computing power.
And some day, a robot -- instead of a human -- might be used to run into a dangerous area, check things out and report back for further instructions.

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Spider Mite Predators Serve As Biological Control

(Dec. 28, 2009) — The control of spider mites, which damage tree leaves, reduce fruit quality and cost growers millions of dollars in the use of pesticide and oil spraying, is being biologically controlled in Pennsylvania apple orchards with two tiny insects known to be natural predators, according to Penn State researchers.

"Predator mite attacking a spider mite."

"Spider mites feed on the chlorophyll in the cells of leaves, damaging their ability to use photosynthesis," said David Biddinger, tree fruit entomologist and biocontrol specialist at the Penn State Fruit Research and Extension Center in Biglerville.
 "When the numbers of mites per leaf reaches 25 to 30, the tree becomes stressed and the leaves start to bronze. This affects the quality of its fruit and in two to three seasons can actually kill small trees."

The two most popular insect specialists used to control
spider mites are a lady bug named Stethorus punctum and a predatory mite named T. pyri. These insects prey on two types of spider mites, the European red mites and the two-spotted spider mites, which are agricultural pests worldwide. Much of Biddinger's work is in Pennsylvania apple orchards, a prime target for both types of pest mites.
Although the lady bug and the predatory mite both hunt spider mites, their ways of tracking them down are different.
"It turns out the predatory mite sort of roams around and bumps into them," said Biddinger. "The lady bug on the other hand is a selective killer, hunting using visual and olfactory cues to prey on spider mites."
The lady bug is tiny, oval, and black and it is a natural killer of pest mites. It is attracted to specific volatile chemical signals given off by the damage the spider mites cause to leaves. It is not just the smell that drives the lady bugs wild; this insect cannot resist the yellowing of the leaves damaged by spider mites. Adult lady bugs can live for over a year and eat up to nine mites an hour or 75 to 100 a day.
The predatory mite is much smaller than the lady bug. It is pear-shaped and is usually creamy-white in color. Young mites develop into adults in a very short time and their voracious appetites make them a formidable enemy to spider mites. Adults have a lifespan of about 75 days and can eat 350 mites during this time.
Reducing pest mite numbers and controlling outbreaks with the aid of mite predators is an important task. The biological control of spider mites reduces the need for mite-controlling chemicals and saves growers millions in integrated pest management costs.

"Biological control is basically using the good bugs to control the bad bugs," said Biddinger.
Growers chose lady bugs as their biological control agent until U.S. Environmental Protection Agency regulations prompted growers to switch to new pesticides that kill lady bugs. The predatory mite, however, was resistant and could live through sprayings. So predatory mites are now the hunter of choice for spider mites.
Biddinger, working with Donald C. Weber, research entomologist, U.S. Department of Agriculture, Agricultural Research Service Invasive Insect Biocontrol and Behavior Laboratory, Maryland, and Larry Hull, professor of entomology, Penn State, published their work in a special issue of Biological Control devoted to ladybugs in agriculture.
"With the pesticides we are using now it is very hard for the lady bug to survive," said Biddinger. "The predatory mite could never exist here before because they could not stand the old pesticides, but they are resistant to the new pesticides. With the predatory mite being more effective than the lady bug, we are probably going to exceed the savings for growers that we had with the lady bug in the past. So far we have reduced miticide use by over 90 percent since we switched. This is saving growers about a million dollars a year and is reducing oil spraying by 45,000 gallons a year."
The State Horticultural Association of Pennsylvania supported this work.

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How the Daisy Got Its Spot: Insect Mimicry

(Dec. 26, 2009) — Dark spots on flower petals are common across many angiosperm plant families and occur on flowers such as some lilies, orchids, and daisies. Much research has been done on the physiological and behavioral mechanisms for how these spots attract pollinators. But have you ever wondered what these spots are composed of, how they develop, or how they only appear on some but not all of the ray florets?

This is the Nieuw morphotype of Gorteria diffusa, which exhibits striking dark petal spots at the bases of some ray florets. Scale bar = 1 cm. (Credit: Courtesy Meredith Murphy Thomas.)


Dr. Meredith Thomas from the University of Cambridge and associates from England and South Africa were interested in exploring these questions and published their findings in the December issue of the American Journal of Botany. They focused on the South African endemic beetle daisy Gorteria diffusa (Asteraceae), which has a unique, raised, dark spot at the base of some of its ray florets.
"I find this plant/pollinator system very exciting to study because of the amazing morphological variation in the flowers between populations," Thomas said. "The spots on the flowers mimic the plant's pollinator, a small fly, which is attracted to the plant because of the spots. The plant is dependent on the pollinator for reproductive success, so it's incredibly important that the plant attracts the flies.
"What we found surprising," Thomas continued, "was how complex the petal spots are in a few populations, when other populations seem to get by with a very simple spot or even no petal spot at all."
By peeling away layers of the tissues that make up the spots on mature ray florets and examining them under a simple dissecting scope, Thomas and associates found that the spots of G. diffusa are more complex than most. These spots are composed of three different types of specialized epidermal cells: the central highlight cells that reflect UV and lack pigment; the interior cells that are shorter, rounder, variously pigmented, and raised above the highlight cells; and, surrounding the spot, a circle of multicellular papillae that are swollen, shiny, and filled with anthocyanin. Moreover, each spot spans four congenitally fused petal lobes, meaning that each lobe contained only part of the spot (and only some cell types) in its genetic makeup.

So what attracts the pollinators? Because there is a lot of spot variation in this species, the authors hypothesize that the elements that are found in common among the various populations, such as the presence of anthocyanin pigment or UV reflectivity, might do the trick.
The authors also wanted to know how only a subset of the floral rays develops a spot. Using scanning electron microscopy the authors looked at how the spot developed, or its ontogeny, over time. They found that only the first few ray florets that develop contain the spots, whereas the rest do not. Thomas noted that "the plant has evolved a very clever way of distributing the pollinator-mimicking spots around the inflorescence so that they appear random, as if a few flies had just landed on the inflorescence, when in fact the position of the spots is mathematically pre-determined according to the plant's phyllotaxy [or the order and location in which new floral organs are initiated]." The authors hypothesize that the genes that control the appearance of the spot are turned on initially and then fade with time, such that only the first, and oldest, rays to develop have the spots. Thus, the development of the spots is complex not only at the cellular level, but at the organismal level as well.
"What we now plan to investigate," concludes Thomas, "is whether the development of this adaptive floral trait is regulated by a similarly complex genetic regulatory pathway, or if this plant has simply co-opted and modified a pathway commonly used in plants to produce other types of specialized surface structures, like hairs.$395. Termite Treatments Termite Bonds Pest Control Termite Real Estate Inspections.
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Microscopic Flower Petal Ridges Flash to Attract Pollinating Insects; Scientists Now Know How Ridges Form

 (Dec. 25, 2009) — Microscopic ridges contouring the surface of flower petals might play a role in flashing that come-hither look pollinating insects can't resist. Michigan State University scientists and colleagues now have figured out how those form.

The result could help researchers learn to enhance plants' pollination success and even could lead to high-grip nanomaterials and "green chemical" feedstocks.
"Surprisingly, our work on plant surface biochemistry became a birds and bees and flowers story," said John Ohlrogge, MSU University Distinguished Professor of plant biology. "It's a fundamental property of plant flowers, and we've discovered a basis of how these ridges are made."
Known for 75 years, the exact biological function and nature of the flower nanoridges still eludes scientists. They might help pollinating insects grip petals, and retain glistening water droplets that could attract the visitors. Because the ridges' spacing is approximately that of visible and ultraviolet light wavelengths, moreover, some recent research suggests they produce an iridescent shimmer that attracts pollinators.

To start, visiting professor Mike Pollard and former Ohlrogge post-doctoral research associates Fred Beisson and Yonghua Li tapped new genetic information to find a mutated strain of the standard research plant Arabidopsis thaliana -- mustard weed. The petals have no such nanoridges because the mutation inhibits production of a polymer that forms the plant cuticle, which separates cell walls from plants' waxy surfaces.
Examining the mutant plants' flowers and comparing them to normal mustard plants under scanning electron microscopes, the researchers found that the ridges form from cutin polyester, not from underlying surfaces as some have speculated. How that occurs -- from surface folding or uneven synthesis of cutin polymer across the cell wall, for example, has yet to be learned.
But the research will open doors to further research based on cuticular nanostructures, the researchers noted in a recent edition of the journal Proceedings of the National Academy of Sciences.
"That could include production of polyesters or related basic chemicals by genetically manipulating plants or microbes" said Beisson, now at Aix Marseille Université in Saint-Paul-lez-Durance, France.

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The Buzz on Fruit Flies: New Role in the Search for Addiction Treatments

 (Dec. 21, 2009) — Fruit flies may seem like unlikely heroes in the battle against drug abuse, but new research suggests that these insects -- already used to study dozens of human disease -- could claim that role. Scientists are reporting that fruit flies can be used as a simpler and more convenient animal model for studying the effects of cocaine and other drugs of abuse on the brain.

Andrew Ewing and colleagues note that laboratory mice, rats, and monkeys have been mainstays in research with the ultimate goal of finding effective medicines for treating addiction. Although these mammals have helped establish the behavioral effects of cocaine on the body, they provide relatively complicated models to study the effects of cocaine and other illicit drugs on the brain and nerves. In the hope for a new simpler animal model they turned to fruit flies, which have many biological similarities to mammals, but are easier to study.

A tiny electrode and pipette inserted into the fruit fly brain make it a simple, convenient model for studying drug abuse in humans. (Credit: American Chemical Society)

The scientists confirmed those hopes in research that involved giving cocaine, amphetamine, methamphetamine, and methylphenidate to fruit flies and then studying brain chemistry with a microelectrode one-twentieth the diameter of a human hair. The results demonstrate that fruit flies are a valid model for studying drug addiction in humans, the scientists say.

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Why Some Insects Can Survive Freezing: Huge X-Ray Microscope Provides Clues

(Dec. 19, 2009) — Using a microscope the size of a football field, researchers from The University of Western Ontario are studying why some insects can survive freezing, while others cannot. Why is this important? Because the common fruit fly (Drosophila melanogaster) is one of the bugs that cannot survive freezing and the little creature just so happens to share much of the same genetic makeup as humans, therefore finding a way to freeze them for research purposes is a top priority for geneticists the world over (about 75 per cent of known human disease genes have a recognizable match in the genetic code of fruit flies).

Synchrotron x-ray visualisation of ice formation in insects during lethal and non-lethal freezing. (Credit: Image courtesy of University of Western Ontario)

And why the large microscope?
"It's the only one in the world that's set up for this kind of imaging on insects," says lead researcher Brent Sinclair of his team's use of the Advanced Photon Source (APS), located near Chicago, Illinois. The APS generates high-energy x-rays that allow Sinclair and his collaborators to film the formation and spread of ice in real time as the maggots freeze.
An assistant professor in Western's Department of Biology, Sinclair explains that the physical processes of ice formation seem to be consistent among species that do and don't survive freezing. However, it seems that the insects that survive freezing have some control over the process of ice formation. They freeze at consistently higher temperatures than those that don't.

Sinclair says this implies that the main adaptations required to survive freezing are at the cellular or biochemical level, rather than because of fundamental structural differences.
"We're comparing Chymomyza amoena, an insect native to Ontario that survives freezing, with Drosophila melanogaster, because they're very close relatives," says Sinclair. "The idea is to find the magic bullet which allows some bugs to survive freezing and some don't. That's the goal here."
The Western-led research was published in the journal PLoS ONE, an peer-reviewed, open-access resource from the Public Library of Science.

Killer Catfish? Venomous Species Surprisingly Common, Study Finds

(Dec. 15, 2009) — Name all the venomous animals you can think of and you probably come up with snakes, spiders, bees, wasps and perhaps poisonous frogs. But catfish?

A new study by University of Michigan graduate student Jeremy Wright finds that at least 1,250 and possibly more than 1,600 species of catfish may be venomous -- far more than previously believed. The research is described in a paper published online Dec. 4 in the open access journal BMC Evolutionary Biology.
Lest anyone have concerns about attacks of killer catfish, rest assured that, at least in North America, these finned fatales use their venom mainly to defend themselves against predatory fish, though they can inflict a painful sting that many fishermen have suffered. In other parts of the world, some catfish do have extremely toxic venoms that can be deadly to humans.

Scientists have focused a great deal of attention of venom produced by snakes and spiders, but venomous fish had been largely neglected, said Wright, who used histological and toxicological techniques, as well as previous studies of evolutionary relationships among catfish species, to catalog the presence of venom glands and investigate their biological effects.
Catfish venom glands are found alongside sharp, bony spines on the edges of the dorsal and pectoral fins, and these spines can be locked into place when the catfish is threatened. When a spine jabs a potential predator, the membrane surrounding the venom gland cells is torn, releasing venom into the wound. In his paper, Wright describes how catfish venoms poison nerves and break down red blood cells, producing such effects as severe pain, reduced blood flow, muscle spasms and respiratory distress. However, because none of the species he examined produces more than three distinct toxins in its venom, each species probably displays only a subset of the whole repertoire of effects.
The main dangers to humans who tangle with North American catfish come not from the initial sting and inflammation, but from secondary bacterial and fungal infections that can be introduced through the puncture wound or when pieces of the spine and other tissue break off in the wound, Wright said. "In such cases, complications associated with these infections and foreign bodies can last several months."
On the evolutionary side, Wright's analyses point to at least two independent origins of catfish venom glands. In addition, the toxic proteins show strong similarities with, and might be derived from, previously characterized toxins found in catfish skin secretions.

Those toxins in catfish skin secretions have been shown to accelerate wound healing in humans, so it's possible that the proteins from their venom glands could have similar properties. Probably not very likely, given the known effects of these venoms on humans, but perhaps worth investigating, Wright said.
"I'm currently working to isolate particular toxins and determine their chemical structures and the genes responsible for their production," he said. "It's a very poorly-studied area, with little in the way of scientific literature to draw on, and my studies are just getting off the ground. So at this point it remains to be seen whether they'll have any therapeutic value, though it's worth pointing out that toxins from the venoms of other organisms -- snakes, cone snails and scorpions, for example -- have all been put to pharmaceutical and therapeutic use."
Further examination of the chemical composition of the venoms also will provide valuable insight into the mechanisms and potential selective factors driving venom evolution in fishes, Wright said.

Wright received financial support from the U-M Museum of Zoology and the U-M Rackham Graduate School.