Brown marmorated stink bugs cause millions of dollars in crop losses across the United States because of the damage their saliva does to plant tissues. Researchers at Penn State have developed methods to extract the insect saliva and identify the major protein components, which could lead to new pest control approaches.”Until now, essentially nothing was known about the composition of stink bug saliva, which is surprising given the importance of these insects as pests and the fact that their saliva is the primary cause of feeding injury to plants and crop losses,” said Gary Felton, professor and head of the Department of Entomology. “Other than using synthetic pesticides, there have been few alternative approaches to controlling these pests. By identifying the major protein components of saliva, it now may be possible to target the specific factors in saliva that are essential for their feeding and, therefore, design new approaches for controlling stink bugs.”The team reported its results in PLOS ONE.According to Felton, stink bugs produce two types of saliva that are required for successful feeding. Watery saliva helps stink bugs to digest their food. Sheath saliva surrounds stink bugs’ mouthparts and hardens to prevent spillage of sap during feeding. The hardened “sheath” remains attached to the plant when the insect is finished feeding.”Unlike a chewing insect, which causes damage by removing plant tissue, stink bugs pierce plant tissue and suck nutrients from the plant,” said Michelle Peiffer, research support assistant. “During this process, stink bugs also deposit saliva onto the plant. The interaction between this saliva and the plant is what causes the cosmetic and physiological changes that make crops unmarketable.”To extract the two types of saliva from brown marmorated stink bugs, Felton and Peiffer first collected adult bugs from homes and fields in central Pennsylvania and maintained them in their laboratory.The researchers chilled the insects on ice. As the insects returned to room temperature, their watery saliva was secreted from the tips of their beaks. …Read more
Why did the armed wing of the Nazi party need to study insects? Tbingen University’s Dr Klaus Reinhardt asked that question while studying documents from the Waffen-SS Entomological Institute, an annex of Dachau concentration camp. It made no sense — during WWII, Germany already had several respected entomological research centers; nor did the SS institute study insects which presented a potential threat to Germany’s all-important food supplies.After combing the archives, and building upon postwar studies, Dr Reinhardt came to the conclusion that, although the institute was intended to combat insect-borne diseases such as typhoid, it also carried out research into whether mosquitoes — which host malaria — could be used in biological warfare. The results of Dr Reinhardt’s research are published in the latest edition of the journal Endeavour.It has been debated for many years whether Nazi Germany sought to produce biological weapons despite Hitler’s ban on them. Dr Reinhardt’s findings are likely to re-ignite that discussion. Heinrich Himmler, head of the SS, commissioned the Entomological Institute in Dachau in January 1942, presumably after reports of lice infestation among SS troops, and following an outbreak of typhoid fever at Neuengamme concentration camp. The instructions Himmler issued in 1942 were for basic research required to combat germ-carrying insects — involving the life cycles, diseases, predators and preferred hosts of beetles, lice, fleas and flies.Dr Reinhardt says that in 1944, the SS Entomological Institute was also tasked with testing various species of mosquito for their ability to survive without food or water — and thus, their suitability to be infected with malaria and air-dropped into enemy territory.Dr Reinhardt examined notes by the institute’s director, Eduard May. Lab reports detailed experiments with anopheles mosquitoes, which can host malaria during part of its development. May recommended the use of one particular anopheles mosquito species which could survive for more than four days. Reinhardt considers this a clear indicator that the insects were to be used as an offensive biological weapon.Dr Reinhardt’s article describes how scientifically more suitable candidates were passed over in favor of May, who was regarded by the regime as ideologically sound. …Read more
Sep. 12, 2013 — Previously believed to be only human-made, a natural example of a functioning gear mechanism has been discovered in a common insect — showing that evolution developed interlocking cogs long before we did.The juvenile Issus – a plant-hopping insect found in gardens across Europe — has hind-leg joints with curved cog-like strips of opposing ‘teeth’ that intermesh, rotating like mechanical gears to synchronise the animal’s legs when it launches into a jump.The finding demonstrates that gear mechanisms previously thought to be solely human-made have an evolutionary precedent. Scientists say this is the “first observation of mechanical gearing in a biological structure.”Through a combination of anatomical analysis and high-speed video capture of normal Issus movements, scientists from the University of Cambridge have been able to reveal these functioning natural gears for the first time. The findings are reported in the latest issue of the journal Science.The gears in the Issus hind-leg bear remarkable engineering resemblance to those found on every bicycle and inside every car gear-box. Each gear tooth has a rounded corner at the point it connects to the gear strip; a feature identical to human-made gears such as bike gears — essentially a shock-absorbing mechanism to stop teeth from shearing off.The gear teeth on the opposing hind-legs lock together like those in a car gear-box, ensuring almost complete synchronicity in leg movement — the legs always move within 30 ‘microseconds’ of each other, with one microsecond equal to a millionth of a second.This is critical for the powerful jumps that are this insect’s primary mode of transport, as even miniscule discrepancies in synchronisation between the velocities of its legs at the point of propulsion would result in “yaw rotation” — causing the Issus to spin hopelessly out of control.”This precise synchronisation would be impossible to achieve through a nervous system, as neural impulses would take far too long for the extraordinarily tight coordination required,” said lead author Professor Malcolm Burrows, from Cambridge’s Department of Zoology.”By developing mechanical gears, the Issus can just send nerve signals to its muscles to produce roughly the same amount of force — then if one leg starts to propel the jump the gears will interlock, creating absolute synchronicity.”In Issus, the skeleton is used to solve a complex problem that the brain and nervous system can’t,” said Burrows. “This emphasises the importance of considering the properties of the skeleton in how movement is produced.””We usually think of gears as something that we see in human designed machinery, but we’ve found that that is only because we didn’t look hard enough,” added co-author Gregory Sutton, now at the University of Bristol.”These gears are not designed; they are evolved — representing high speed and precision machinery evolved for synchronisation in the animal world.”Interestingly, the mechanistic gears are only found in the insect’s juvenile — or ‘nymph’ — stages, and are lost in the final transition to adulthood. These transitions, called ‘molts’, are when animals cast off rigid skin at key points in their development in order to grow.It’s not yet known why the Issus loses its hind-leg gears on reaching adulthood. The scientists point out that a problem with any gear system is that if one tooth on the gear breaks, the effectiveness of the whole mechanism is damaged. While gear-teeth breakage in nymphs could be repaired in the next molt, any damage in adulthood remains permanent.It may also be down to the larger size of adults and consequently their ‘trochantera’ — the insect equivalent of the femur or thigh bones. The bigger adult trochantera might allow them to can create enough friction to power the enormous leaps from leaf to leaf without the need for intermeshing gear teeth to drive it, say the scientists.Each gear strip in the juvenile Issus was around 400 micrometres long and had between 10 to 12 teeth, with both sides of the gear in each leg containing the same number — giving a gearing ratio of 1:1.Unlike human-made gears, each gear tooth is asymmetrical and curved towards the point where the cogs interlock — as human-made gears need a symmetric shape to work in both rotational directions, whereas the Issus gears are only powering one way to launch the animal forward.While there are examples of apparently ornamental cogs in the animal kingdom — such as on the shell of the cog wheel turtle or the back of the wheel bug — gears with a functional role either remain elusive or have been rendered defunct by evolution.The Issus is the first example of a natural cog mechanism with an observable function, say the scientists.Read more
Aug. 14, 2013 — Comparing plant communities today with a survey taken 50 years ago, a UA-led research team is providing the first on-the-ground evidence for Southwestern plants being pushed to higher elevations by an increasingly warmer and drier climate.In a rare opportunity to directly compare today’s plant communities with a survey taken in the same area 50 years ago, a University of Arizona-led research team has provided the first on-the-ground evidence that Southwestern plants are being pushed to higher elevations by an increasingly warmer and drier climate.The findings confirm that previous hypotheses are correct in their prediction that mountain communities in the Southwest will be strongly impacted by an increasingly warmer and drier climate, and that the area is already experiencing rapid vegetation change.In a rare opportunity to obtian a “before — after” look, researchers studied current plant communities along the same transect already surveyed in 1963: the Catalina Highway, a road that winds all the way from low-lying desert to the top of Mount Lemmon, the tallest peak in the Santa Catalina Mountains northeast of Tucson.”Our study provides the first on-the-ground proof of plants being forced significantly upslope due to climate warming in southern Arizona,” said Richard C. Brusca, a research scientist in the UA’s department of ecology and evolutionary biology who led the study together with Wendy Moore, an assistant professor in the UA’s department of entomology. “If climate continues to warm, as the climate models predict, the subalpine mixed conifer forests on the tops of the mountains — and the animals dependent upon them — could be pushed right off the top and disappear.”The study, published in the journal Ecology and Evolution, was made possible by the existence of a dataset compiled 50 years ago by Robert H. Whittaker, often referred to as the “father of modern plant ecology,” and his colleague, William Niering, who catalogued the plants they encountered along the Catalina Highway.Focusing on the 27 most abundantly catalogued plant species, Brusca and Moore discovered that three quarters of them have shifted their range significantly upslope, in some cases as much as a thousand feet, or now grow in a narrower elevation range compared to where Whittaker and Niering found them in 1963.Specifically, Moore and her team found that the lowermost boundaries for 15 of the species studied have moved upslope; eight of those species now first appear more than 800 feet higher than where Whittaker and Niering first encountered them. Sixteen of the studied species are now restricted to a narrower band of elevation, the researchers noticed. As far as the plants’ upper elevation limits were concerned, the researchers observed a mixed trend: They found it to be higher for four species, lower for eight species and unchanged for 15.For example, in 1963 Whittaker and Niering recorded alligator juniper as a component of upland desert and grassland communities in the Catalina Mountains, beginning at an elevation of just 3,500 feet. Today, one has to drive to the 5,000-foot elevation marker on the Catalina Highway to see the first live alligator juniper trees in upland habitats.According to the authors, the main point emerging from the study is that plant communities on the mountain were different 50 years ago because plant species do not necessarily move toward higher elevations as a community. Rather, individual species shift their ranges independently, leading to a reshuffling of plant communities.The scientists in this multidisciplinary group gathered the data during fieldwork in 2011, and included UA postdoctoral fellows and professors from several programs, including the UA departments of entomology and ecology and evolutionary biology, the Center for Insect Science and the Institute for the Environment, as well as botanists from the Arizona-Sonora Desert Museum.Based on studies done by other scientists, including UA researchers, the researchers believe that a “thirstier” atmosphere might be a major driver behind the shifts in plant distribution, possibly even more so than lack of precipitation. As the atmosphere becomes warmer and drier, plants loose more water through their leave openings and become water-stressed.According to the authors, the results are consistent with a trend scientists have established for the end of the Pleistocene, a period of repeated glaciations that ended about 12,000 years ago. …Read more
Aug. 5, 2013 — Scientists at the University of East Anglia have shown that sequencing the DNA of crushed up creepy crawlies can accelerate the monitoring and cataloguing of biodiversity around the world.Research published today in the journal Ecology Letters shows that a process known as ‘metabarcoding’ is much faster than and just as reliable as standard biodiversity datasets assembled with traditional labour-intensive methods.The breakthrough means that changing environments and endangered species can be monitored more easily than ever before. It could help researchers find endangered tree kangaroos in Papua New Guinea, discover which moths will be wiped out by climate change, and restore nature to heathlands in the UK, rubber plantations in China, and oil-palm plantations in Sumatra.Lead researcher Dr Douglas Yu, from UEA’s school of Biological Sciences, said: “Every living organism contains DNA, and even small fragments of that DNA can be used to identify species.”We collected lots of insects and other creepy-crawlies, ground them up into an ‘insect soup’, and read the DNA using sequencers that are now cheap enough to use weekly or even daily.”We compared our results with high-quality datasets collected in Malaysia, China and the UK which combined more than 55,000 arthropod and bird specimens and took experts 2,505 hours to identify. These kinds of datasets are the gold standard for biodiversity monitoring but are so expensive to compile that that we cannot use them for regular monitoring. Thus, conservation biologists and environmental managers are forced to work with little information.”We found that our ‘soup’ samples give us the same biodiversity information as the gold-standard datasets. They are also more comprehensive, many times quicker to produce, less reliant on taxonomic expertise, and they have the added advantage of being verifiable by third parties.”The findings are important because they show that metabarcoding can be used to reliably inform policy and environmental management decisions.Dr Yu added: “If the environment changes for the better or for the worse, what lives in that environment changes as well. Insect soup becomes a sensitive thermometer for the state of nature.”For instance, we showed that if the UK Forestry Commission ploughs up some of the grass-covered trackways that run between our endangered heathland habitats, populations of rare spiders, beetles, and other creepy-crawlies can reconnect along those trackways, helping to stave off extinction.”We are now working with the WWF and Copenhagen University to apply the method to bloodsucking leeches to look for endangered mammals in Vietnamese and Laotian rainforests. By creating a ‘leech soup’ we can get a list of mammals and know more about whether park conservation is working.”Each soup combines hundreds to thousands of insects caught using insect traps. The numbers captured amount to a tiny fraction of their overall populations and pose no threat to endangered species.The research was funded by the Natural Environment Research Council UK, the Chinese Academy of Sciences, the National Science Foundation of China, and the Yunnan provincial government.’Reliable, verifiable, and efficient monitoring of biodiversity via metabarcoding’ is published in the journal Ecology Letters on August 5, 2013.Read more
July 18, 2013 — Neurobiologists from the University of Leicester have shown that insect limbs can move without muscles – a finding that may provide engineers with new ways to improve the control of robotic and prosthetic limbs.Their work helps to explain how insects control their movements using a close interplay of neuronal control and ‘clever biomechanical tricks,’ says lead researcher Dr Tom Matheson, a Reader in Neurobiology at the University of Leicester.In a study published today in the journal Current Biology, the researchers show that the structure of some insect leg joints causes the legs to move even in the absence of muscles. So-called ‘passive joint forces’ serve to return the limb back towards a preferred resting position.The passive movements differ in limbs that have different behavioural roles and different musculature, suggesting that the joint structures are specifically adapted to complement muscle forces. The researchers propose a motor control scheme for insect limb joints in which not all movements are driven by muscles.The study was funded by the Biotechnology and Biological Sciences Research Council (BBSRC), The Royal Society, and the Heinrich Hertz-Foundation of the German State of North Rhine-Westphalia.Dr Matheson, of the Department of Biology, said: “It is well known that some animals store energy in elastic muscle tendons and other structures. Such energy storage permits forces to be applied explosively to generate movements that are much more rapid than those which may be generated by muscle contractions alone. This is, for example, crucial when grasshoppers or fleas jump.“This University of Leicester study provides a new insight into the ways that energy storage mechanisms can operate in a much wider range of movements.“Our work set out to identify how the biomechanical properties of the limbs of a range of insects influence relatively slow movements such as those that occur during walking, scratching or climbing. The surprising result was that although some movements are influenced by properties of the muscles and tendons, other movements are generated by forces that arise from within the joints themselves.“Even when we removed all of the muscles and associated tissues from a particular joint at the ‘knee’ of a locust, the lower part of the limb (the tibia) still moved back towards a midpoint from extended angles.”Dr Matheson said that it was known from previous studies that some movements can be generated by spring-like properties of limbs, but the team was surprised to find passive forces that contribute to almost all movements made by the limbs that were studied – not just the highly specialised rapid movements needed to propel powerful jumps and kicks.“We expected the forces to be generated within the muscles of the leg, but found that some continued to occur even when we detached both muscles – the extensor and the flexor tibiae – from the tibia.“In the locust hind leg, which is specialised for jumping and kicking, the extensor muscle is much larger and stronger than the antagonist flexor muscle. This enables the animal to generate powerful kicks and jumps propelled by extensions of the tibia that are driven by contractions of the extensor muscle. When locusts prepare to jump, large amounts of energy generated by the extensor muscle are stored in the muscle’s tendon and in the hard exoskeleton of the leg.“Surprisingly, we noticed that when the muscles were removed, the tibia naturally flexed back towards a midpoint, and we hypothesised that these passive return movements might be counterbalancing the strong extensor muscle.”Jan M. Ache, a Masters student from the Department of Animal Physiology at the University of Cologne who worked in Matheson’s lab and is the first author on the paper, continues: “To test this idea we looked at the literature and examined other legs where the extensor and flexor muscles are more closely balanced in size or strength, or where the flexor is stronger than the extensor.“We found that the passive joint forces really do counterbalance the stronger of the flexor or extensor muscle in the animals and legs we looked at. In the horsehead grasshopper, for example, passive joint forces even differ between the middle legs (which are primarily used for walking) and the hind legs (which are adapted for jumping), even in the same individual animal. …Read more
July 4, 2013 — Flapping insects build up an electrical charge that may make them more easily snared by spider webs, according to a new study by University of California, Berkeley, biologists.The positive charge on an insect such as a bee or fly attracts the web, which is normally negatively or neutrally charged, increasing the chances that an insect flying by will contact and stick to the web, said UC Berkeley post-doctoral fellow Victor Manuel Ortega-Jimenez.He also suspects that light flexible spider silk, the kind used for make the spirals on top of the stiffer silk that forms the spokes of a web, may have developed because it more easily deforms in the wind and electrostatic charges to aid prey capture.”Electrostatic charges are everywhere, and we propose that this may have driven the evolution of specialized webs,” he said.Ortega-Jimenez, who normally studies hummingbird flight, became interested in spider webs while playing with his four-year-old daughter.”I was playing with my daughter’s magic wand, a toy that produces an electrostatic charge, and I noticed that the positive charge attracted spider webs,” he said. “I then realized that if an insect is positively charged too it could perhaps attract an oppositely charged spider web to affect the capture success of the spider web.”In fact, insects easily develop several hundred volts of positive charge from the friction of wings against air molecules or by contacting a charged surface. This is small compared to the several thousand volts we develop when walking across a rug and which gives us a shock when we touch a doorknob, but is sufficient to allow a bee to electrostatically draw pollen off a flower before landing.To test his spider web hypothesis, Ortega-Jimenez sought out cross-spider (Araneus diadematus) webs along streams in Berkeley and brought them into the lab. He then used an electrostatic generator to charge up dead insects — aphids, fruit flies, green-bottle flies, and honey bees — and drop them into a neutral, grounded web.”Using a high speed camera, you can clearly see the spider web is deforming and touching the insect before it reaches the web,” he said. Insects without a charge did not do this. “You would expect that if the web is charged negatively, the attraction would increase.”Ortega-Jimenez plans to conduct further tests at UC Berkeley to determine whether this effect occurs in the wild, and find out whether static charges on webs attract more dirt and pollen and thus are a major reason orb web weavers rebuild them daily.Read more
June 24, 2013 — Researchers say they now know what allows some Western corn rootworms to survive crop rotation, a farming practice that once effectively managed the rootworm pests. The answer to the decades-long mystery of rotation-resistant rootworms lies — in large part — in the rootworm gut, the team reports.The findings appear in the Proceedings of the National Academy of Sciences.Differences in the relative abundance of certain bacterial species in the rootworm gut help the adult rootworm beetles feed on soybean leaves and tolerate the plant’s defenses a little better, the researchers report. This boost in digestive finesse allows rotation-resistant beetles to survive long enough to lay their eggs in soybean fields. Their larvae emerge the following spring and feast on the roots of newly planted corn.”These insects, they have only one generation per year,” said University of Illinois entomology department senior scientist Manfredo Seufferheld, who led the study. “And yet within a period of about 20 years in Illinois they became resistant to crop rotation. What allowed this insect to adapt so fast? These bacteria, perhaps.”Controlling rootworms is an expensive concern faced by all Midwest corn growers, said study co-author Joseph Spencer, an insect behaviorist at the Illinois Natural History Survey (part of the Prairie Research Institute at the U. of I.). Yield losses, the use of insecticides and corn hybrids engineered to express rootworm-killing toxins in their tissues cost U.S. growers at least $1 billion a year.In a 2012 study, Seufferheld, Spencer and their colleagues reported that rotation-resistant rootworm beetles were better able than their nonresistant counterparts to tolerate the defensive chemicals produced in soybeans leaves. …Read more
June 20, 2013 — Does your salad know what time it is? It may be healthier for you if it does, according to new research from Rice University and the University of California at Davis.”Vegetables and fruits don’t die the moment they are harvested,” said Rice biologist Janet Braam, the lead researcher on a new study this week in Current Biology. “They respond to their environment for days, and we found we could use light to coax them to make more cancer-fighting antioxidants at certain times of day.” Braam is professor and chair of Rice’s Department of Biochemistry and Cell Biology.Braam’s team simulated day-night cycles of light and dark to control the internal clocks of fruits and vegetables, including cabbage, carrots, squash and blueberries. The research is a follow-up to her team’s award-winning 2012 study of the ways that plants use their internal circadian clocks to defend themselves from hungry insects. That study found that Arabidopsis thaliana — a widely used model organism for plant studies — begins ramping up production of insect-fighting chemicals a few hours before sunrise, the time that hungry insects begin to feed.Braam said the idea for the new research came from a conversation with her teenage son.”I was telling him about the earlier work on Arabidopsis and insect resistance, and he said, ‘Well, I know what time of day I’ll eat my vegetables!’ Braam said. “That was my ‘aha!’ moment. He was thinking to avoid eating the vegetables when they would be accumulating the anti-insect chemicals, but I knew that some of those chemicals were known to be valuable metabolites for human health, so I decided to try and find out whether vegetables cycle those compounds based on circadian rhythms.”Arabidopsis and cabbage are related, so Braam’s team began their research by attempting to “entrain” the clocks of cabbage in the same way they had Arabidopsis. Entrainment is akin to the process that international travelers go through as they recover from jet lag. After flying to the other side of the globe, travelers often have trouble sleeping until their internal circadian clock resets itself to the day-night cycle in their new locale.Using controlled lighting in a sealed chamber, Rice graduate student and study lead author Danielle Goodspeed found she could entrain the circadian clocks of postharvest cabbage just as she had those of Arabidopsis in the 2012 study. Following the success with cabbage, Goodspeed and co-authors John Liu and Zhengji Sheng studied spinach, lettuce, zucchini, carrots, sweet potatoes and blueberries.”We were able to entrain each of them, even the root vegetables,” Goodspeed said. …Read more
June 3, 2013 — When it comes to saving its own hide, the tiger moth can predict the future.A new study by researchers at Wake Forest University shows Bertholdia trigona, a species of tiger moth found in the Arizona desert, can tell if an echo-locating bat is going to attack it well before the predator swoops in for the kill — making the intuitive, tiny-winged insect a master of self-preservation.Predators in the nightA bat uses sonar to hunt at night. The small mammal emits a series of ultrasonic cries and listens carefully to the echoes that return. By determining how long it takes the sound to bounce back, the bat can figure out how far away its prey is.Aaron Corcoran and William Conner of Wake Forest previously discovered Bertholdia trigona defends itself by jamming its predators’ sonar. Conner, a professor of biology, said the tiger moth has a blister of cuticle on either side of its thorax called a tymbal. It flexes this structure to create a high-pitched, clicking sound.The moth emits more than 4,500 clicks per second right when the bat would normally attack, jamming its sonar.”It is the only animal in the world we know of that can jam its predator’s sonar,” Conner said. “Bats and tiger moths are in the midst of an evolutionary arms race.”The new study published May 6 in the journal PLOS ONE, shows that tiger moths can tell when it is time to start clicking by listening for a telltale change in the repetition rate of the bat’s cries and an increase in sound intensity. The combination of these two factors tells the moth that it has been targeted.Conner’s team used high-speed infrared cameras to create 3D maps of the flight paths of bats attacking tiger moths. They then used an ultrasonic microphone to measure the rate of bat cries and moth clicks.Normally, a bat attack starts with relatively intermittent cries. As it gets closer to the moth, a bat increases the rate at which it produces cries — painting a clearer picture of the moth’s location.Conner’s team found that soon after the bats detected and targeted their prey, moths increased their rate of clicking dramatically, causing the predators to veer off course. The sonar jamming works 93 percent of the time. …Read more
Apr. 15, 2013 — The invasive kudzu bug has the potential to be a major agricultural pest, causing significant damage to economically important soybean crops. Conventional wisdom has held that the insect pests will be limited to areas in the southern United States, but new research from North Carolina State University shows that they may be able to expand into other parts of the country.
Kudzu bugs (Megacopta cribraria) are native to Asia, and were first detected in the U.S. in Georgia in 2009. They have since expanded their territory as far north as Virginia. The bugs have an interesting life cycle, which has been thought to be a limiting factor on far they can spread.
Eggs laid in the spring hatch into a first generation, which we’ll call “Generation A.” The immature bugs of Generation A normally feed on kudzu plants until they reach adulthood, when they have been known to move into commercial soybean fields. These mature adults lay eggs that hatch into Generation B during the summer months. Generation B kudzu bugs can feed on soybean crops during both their immature and adult life stages, causing significant crop damage.
Because the immature Generation A kudzu bugs have only been seen to feed on kudzu, researchers thought that the pest would not be able to migrate to northern and western parts of the United States, where kudzu doesn’t grow. But now it’s not so clear.
Under controlled conditions in a greenhouse laboratory, researchers at NC State found that immature Generation A kudzu bugs were not limited to feeding on kudzu — they were able to feed exclusively on soybeans, reach maturity and reproduce.
“Researchers began seeing some of this behavior in the wild in 2012 and, while those data aren’t quite ready for publication, our lab work and the field observations indicate that kudzu bugs are potentially capable of spreading into any part of the U.S. where soybeans are grown. And soybeans are grown almost everywhere,” says Dr. Dominic Reisig, an assistant professor of entomology at NC State and co-author of a paper on the research. “It also means that both annual generations of kudzu bugs could attack soybean crops in areas where the bug is already established, which would double the impact on farmers.”Read more
Apr. 22, 2013 — A new review of insect pollinators of crops and wild plants has concluded they are under threat globally from a cocktail of multiple pressures, and their decline or loss could have profound environmental, human health and economic consequences.
Globally, insects provide pollination services to about 75% of crop species and enable reproduction in up to 94% of wild flowering plants. Pollination services provided by insects each year worldwide are valued at over US$200 billion.
The review, published April 22, 2013 in the scientific journal Frontiers in Ecology and the Environment, was carried out by an international team of 40 scientists from 27 institutions involved in the UK’s Insect Pollinators Initiative (IPI), a £10M research programme investigating the causes and consequences of pollinator decline.
Dr Adam Vanbergen from the UK’s Centre for Ecology & Hydrology and science coordinator of the IPI led the review. He said, “There is no single smoking gun behind pollinator declines, instead there is a cocktail of multiple pressures that can combine to threaten these insects. For example, the loss of food resources in intensively-farmed landscapes, pesticides and diseases are individually important threats, but are also likely to combine and exacerbate the negative impacts on pollinators.”
The review concluded that:
Pollinator populations are declining in many regions, threatening human food supplies and ecosystem functions
A suite of interacting pressures are having an impact on pollinator health, abundance, and diversity. These include land-use intensification, climate change, and the spread of alien species and diseases
A complex interplay between pressures (e.g. lack of food sources, diseases, and pesticides) and biological processes (e.g. species dispersal and interactions) at a range of scales (from genes to ecosystems) underpins the general decline in insect-pollinator populations
Interdisciplinary research and stakeholder collaboration are needed to help unravel how these multiple pressures affect different pollinators and will provide evidence-based solutions
Current options to alleviate the pressure on pollinators include establishment of effective habitat networks, broadening of pesticide risk assessments, and the development and introduction of innovative disease therapies
Co-author Professor Simon Potts from the University of Reading said, “Pollinators are the unsung heroes of the insect world and ensure our crops are properly pollinated so we have a secure supply of nutritious food in our shops. The costs of taking action now to tackle the multiple threats to pollinators is much smaller than the long-term costs to our food security and ecosystem stability. Failure by governments to take decisive steps now only sets us up for bigger problems in the future.”
Co-author Professor Graham Stone at Edinburgh University’s Institute of Evolutionary Biology said, “a major challenge is going to be understanding the whole ecosystem effects of the specific threats faced by specific pollinators. Complicated as this is, this is nevertheless what we need to do if we want to predict overall impacts on pollination services.”
The Insect Pollinators Initiative (IPI) is funded jointly by the BBSRC, Defra, NERC, the Scottish Government and the Wellcome Trust, under the auspices of the Living with Environmental Change programme.Read more
May 1, 2013 — Research in the wake of Colony Collapse Disorder, a mysterious malady afflicting (primarily commercial) honey bees, suggests that pests, pathogens and pesticides all play a role. New research indicates that the honey bee diet influences the bees’ ability to withstand at least some of these assaults. Some components of the nectar and pollen grains bees collect to manufacture food to support the hive increase the expression of detoxification genes that help keep honey bees healthy.
The findings appear in the Proceedings of the National Academy of Sciences.
University of Illinois professor of entomology May Berenbaum, who led the study, said that many organisms use a group of enzymes called cytochrome P450 monooxygenases to break down foreign substances such as pesticides and compounds naturally found in plants, known as phytochemicals. However, honey bees have relatively few genes dedicated to this detoxification process compared to other insect species, she said.
“Bees feed on hundreds of different types of nectar and pollen, and are potentially exposed to thousands of different types of phytochemicals, yet they only have one-third to one-half the inventory of enzymes that break down these toxins compared to other species,” Berenbaum said.
Determining which of the 46 P450 genes in the honey bee genome are used to metabolize constituents of their natural diet and which are used to metabolize synthetic pesticides became a “tantalizing scientific question” to her research team, Berenbaum said.
“Every frame of honey (in the honey bee hive) is phytochemically different from the next frame of honey because different nectars went in to make the honey. If you don’t know what your next meal is going to be, how does your detoxification system know which enzymes to upregulate?” Berenbaum said.
Research had previously shown that eating honey turns on detoxification genes that metabolize the chemicals in honey, but the researchers wanted to identify the specific components responsible for this activity. To do this, they fed bees a mixture of sucrose and powdered sugar, called bee candy, and added different chemical components in extracts of honey. They identified p-coumaric acid as the strongest inducer of the detoxification genes.
“We found that the perfect signal, p-coumaric acid, is in everything that bees eat — it’s the monomer that goes into the macromolecule called sporopollenin, which makes up the outer wall of pollen grains. It’s a great signal that tells their systems that food is coming in, and with that food, so are potential toxins,” Berenbaum said.
Her team showed that p-coumaric acid turns on not only P450 genes, but representatives of every other type of detoxification gene in the genome. This signal can also turn on honey bee immunity genes that code for antimicrobial proteins.
According to Berenbaum, three other honey constituents were effective inducers of these detoxification enzymes. These components probably originate in the tree resins that bees use to make propolis, the “bee glue” which lines all of the cells and seals cracks within a hive.
“Propolis turns on immunity genes — it’s not just an antimicrobial caulk or glue. It may be medicinal, and in fact, people use it medicinally, too,” Berenbaum said.
Many commercial beekeepers use honey substitutes such as high-fructose corn syrup or sugar water to feed their colonies. Berenbaum believes the new research shows that honey is “a rich source of biologically active materials that truly matter to a bee.”
She hopes that future testing and development will yield honey substitutes that contain p-coumaric acid so beekeepers can enhance their bees’ ability to withstand pathogens and pesticides.
Although she doesn’t recommend that beekeepers “rush out and dump p-coumaric acid into their high fructose corn syrup,” she hopes that her team’s research can be used as the basis of future work aimed at improving bee health.
“If I were a beekeeper, I would at least try to give them some honey year-round,” Berenbaum said, “because if you look at the evolutionary history of Apis mellifera, this species did not evolve with high fructose corn syrup. It is clear that honey bees are highly adapted to consuming honey as part of their diet.”Read more
May 29, 2013 — In one of the first successful attempts at genetically engineering mosquitoes, HHMI researchers have altered the way the insects respond to odors, including the smell of humans and the insect repellant DEET. The research not only demonstrates that mosquitoes can be genetically altered using the latest research techniques, but paves the way to understanding why the insect is so attracted to humans, and how to block that attraction. “The time has come now to do genetics in these important disease-vector insects.
I think our new work is a great example that you can do it,” says Leslie Vosshall, an HHMI investigator at The Rockefeller University who led the new research, published May 29, 2013 in the journal Nature.
In 2007, scientists announced the completion of the full genome sequence of Aedes aegypti, the mosquito that transmits dengue and yellow fever. A year later, when Vosshall became an HHMI investigator, she shifted the focus of her lab from Drosophila flies to mosquitoes with the specific goal of genetically engineering the insects. Studying mosquitoes appealed to her because of their importance as disease carriers, as well as their unique attraction to humans.
Vosshall’s first target: a gene called orco, which her lab had deleted in genetically engineered flies 10 years earlier. “We knew this gene was important for flies to be able to respond to the odors they respond to,” says Vosshall. “And we had some hints that mosquitoes interact with smells in their environment, so it was a good bet that something would interact with orco in mosquitoes.”
Vosshall’s team turned to a genetic engineering tool called zinc-finger nucleases to specifically mutate the orco gene in Aedes aegypti. They injected the targeted zinc-finger nucleases into mosquito embryos, waited for them to mature, identified mutant individuals, and generated mutant strains that allowed them to study the role of orco in mosquito biology. The engineered mosquitoes showed diminished activity in neurons linked to odor-sensing. Then, behavioral tests revealed more changes.
When given a choice between a human and any other animal, normal Aedes aegypti will reliably buzz toward the human. But the mosquitoes with orco mutations showed reduced preference for the smell of humans over guinea pigs, even in the presence of carbon dioxide, which is thought to help mosquitoes respond to human scent. “By disrupting a single gene, we can fundamentally confuse the mosquito from its task of seeking humans,” says Vosshall. But they don’t yet know whether the confusion stems from an inability to sense a “bad” smell coming from the guinea pig, a “good” smell from the human, or both. Next, the team tested whether the mosquitoes with orco mutations responded differently to DEET. When exposed to two human arms — one slathered in a solution containing 10 percent DEET, the active ingredient in many bug repellants, and the other untreated — the mosquitoes flew equally toward both arms, suggesting they couldn’t smell the DEET. But once they landed on the arms, they quickly flew away from the DEET-covered one. “This tells us that there are two totally different mechanisms that mosquitoes are using to sense DEET,” explains Vosshall. “One is what’s happening in the air, and the other only comes into action when the mosquito is touching the skin.” Such dual mechanisms had been discussed but had never been shown before.
Vosshall and her collaborators next want to study in more detail how the orco protein interacts with the mosquitoes’ odorant receptors to allow the insects to sense smells. “We want to know what it is about these mosquitoes that makes them so specialized for humans,” she says. “And if we can also provide insights into how existing repellants are working, then we can start having some ideas about what a next-generation repellant would look like.”Read more
May 29, 2013 — Honey bees don’t start out knowing how to find flowers or even how to get around outside the hive. Before they can forage, they must learn how to navigate a changing landscape and orient themselves in relation to the sun.
In a new study, researchers report that a regulatory gene known to be involved in learning and the detection of novelty in vertebrates also kicks into high gear in the brains of honey bees when they are learning how to find food and bring it home.
Activity of this gene, called Egr, quickly increases in a region of the brain known as the mushroom bodies whenever bees try to find their way around an unfamiliar environment, the researchers observed. This gene is the insect equivalent of a transcription factor found in mammals. Transcription factors regulate the activity of other genes.
The researchers found that the increased Egr activity did not occur as a result of exercise, the physical demands of learning to fly or the task of memorizing visual cues; it increased only in response to the bees’ exposure to an unfamiliar environment. Even seasoned foragers had an uptick in Egr activity when they had to learn how to navigate in a new environment.
“This discovery gives us an important lead in figuring out how honey bees are able to navigate so well, with such a tiny brain,” said Gene Robinson, a professor of entomology and neuroscience and director of the Institute for Genomic Biology at the University of Illinois. “And finding that it’s Egr, with all that this gene is known to do in vertebrates, provides another demonstration that some of the molecular mechanisms underlying behavioral plasticity are deeply conserved in evolution.” Robinson led the study with graduate student Claudia Lutz.
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- C. C. Lutz, G. E. Robinson. Activity-dependent gene expression in honey bee mushroom bodies in response to orientation flight. Journal of Experimental Biology, 2013; 216 (11): 2031 DOI: 10.1242/jeb.084905
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