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Diamondback moth uses plant defense substances as oviposition cues

Date:September 10, 2020Source:Max Planck Institute for Chemical EcologySummary:Researchers showed that isothiocyanates produced by cruciferous plants to fend off pests serve as oviposition cues. The scientists identified two olfactory receptors whose sole function is to detect these defense substances and to guide female moths to the ideal sites to lay their eggs. They uncovered the molecular mechanism that explains why some insects that specialize in feeding on certain host plants are attracted by substances that are supposed to keep pests away.Share:    FULL STORY


A research team from the Nanjing Agricultural University in Nanjing, China, and the Max Planck Institute for Chemical Ecology in Jena, Germany, showed that isothiocyanates produced by cruciferous plants to fend off pests serve as oviposition cues. The plant defense substances serve as odor signals for females of the diamondback moth to lay their eggs on these plants. The scientists identified two olfactory receptors whose sole function is to detect these defense substances and to guide the moths to the ideal oviposition sites. They uncovered the molecular mechanism that explains why some insects that specialize in feeding on certain host plants are attracted by substances that are supposed to keep pests away.

From repellent to attractant

Cruciferous plants, such as cabbage, rape (canola), mustard and horseradish, produce glucosinolates. Upon mechanical damage of the plant tissues, e.g. caused by a chewing insect, glucosinolates are hydrolyzed by the endogenous plant enzyme myrosinase. This leads to the formation of a variety of toxic breakdown products, mainly isothiocyanates, to defend themselves against voracious insects. This defense mechanism is very effective against most herbivores. The diamondback moth Plutella xylostella, however, has evolved mechanisms of its own to outwit this defense: It is able to feed successfully on plants of the cabbage family and make use of the plants for its own reproductive purposes.

“We wanted to know whether the moths use isothiocyanates as odor cues to locate their host plants. In fact, behavioral experiments showed that three isothiocyanates are key signals for female moths to locate and lay eggs on cruciferous plants,” says study leader Shuang-Lin Dong from Nanjing Agricultural University.

Two olfactory receptors specialized on isothiocyanates control egg-laying

The main scientific question was, what are the molecular mechanisms on which female Plutella xylostella moths base their choice of the oviposition site? The researchers therefore analyzed, which olfactory receptors were highly expressed in female moths, and studied the function of these receptors in the frog oocytes. “With this method, we were able to investigate which odors an individual receptor was responding to. We showed that two receptors, OR35 and OR49, responded to the three isothiocyanates that we had previously identified as being crucial for oviposition,” says Markus Knaden from the Max Planck Institute in Jena. These two receptors did not respond to any other plant-related odors or to the sex pheromones of the moths. Presumably, OR35 and OR49 evolved to detect precisely those egg-laying signals. “We were surprised that even two receptors are specifically tuned to the isothiocyanates. The two receptors, however, detect the isothiocyanates with different sensitivities. We hypothesize that the more sensitive receptor could make sure that female moths locate plants from a distance, while the other may help to provide a more accurate detection of the isothiocyanate concentration. This will give the female moths more information about the substrate on which they will lay their eggs,” says Shuang-Lin Dong.

Validation of gene function using CRISPR-Cas9 gene knockout techniques

The researchers used the CRISPR-Cas9 genetic scissors to knock out the genes encoding the two receptors in moths. This method is used to test the function of a specific gene. For egg-laying assays, they used plants of the thale cress Arabidopsis thaliana, a model plant that belongs to the cruciferous plant family. Some of these plants were unmodified and produced isothiocyanates that were attractive to the moths, whereas the others were mutants that were unable to produce isothiocyanates. When one of the two receptors was inactivated, the moths laid considerably fewer eggs on the isothiocyanates-emitting plants. When both receptors were knocked out, the moths were unable to discriminate between unmodified Arabidopsis plants and the mutant plants.

Cheaters in plant-insect interactions

In the course of evolution, plants have developed various strategies to defend themselves against herbivores. A crucial part of plant-insect interaction is chemical communication. “In most cases, it is useful for a plant to communicate to potential herbivores that its defense system is already activated. However, there will be always someone who misuses the communication for its own benefit, like in our case the diamondback moth, which uses a plant defense signal as an attractant and lays eggs and spreads on this plant,” says Markus Knaden. Finding out how these “cheaters” outwit plant defenses and even use these defenses for their own purposes could help improve the control of global crop pests (such as the diamondback moth): “Our results offer various approaches to control this pest: On the one hand, we could use the identified isothiocyanates or other attractive substances as attractants to trap these pests. On the other hand, we could try to develop chemical agents to interrupt or block the perception of the isothiocyanates and thus interfere with the females’ location of their host plants,” summarizes Shuang-Lin Dong.

Further investigations are planned to study whether other insects that attack cruciferous plants also use special receptors to detect isothiocyanates and to locate the plants for oviposition. The results may provide information on the extent to which the perception of these odors by specialized receptors is also conserved in other species.


Story Source:

Materials provided by Max Planck Institute for Chemical EcologyNote: Content may be edited for style and length.


Journal Reference:

  1. Xiao-Long Liu, Jin Zhang, Qi Yan, Chun-Li Miao, Wei-Kang Han, Wen Hou, Ke Yang, Bill S. Hansson, Ying-Chuan Peng, Jin-Meng Guo, Hao Xu, Chen-Zhu Wang, Shuang-Lin Dong, Markus Knaden. The Molecular Basis of Host Selection in a Crucifer-Specialized MothCurrent Biology, 2020; DOI: 10.1016/j.cub.2020.08.047

Cite This Page:

Max Planck Institute for Chemical Ecology. “Diamondback moth uses plant defense substances as oviposition cues.” ScienceDaily. ScienceDaily, 10 September 2020. <www.sciencedaily.com/releases/2020/09/200910120123.htm>.

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Farm Weekly

Russian wheat aphid infiltrates south east

26 Aug 2020, 10 a.m.Cropping NewsAaDiscolouration and streaking on a wheat leaf caused by the exotic cereal pest, Russian wheat aphid.

 Discolouration and streaking on a wheat leaf caused by the exotic cereal pest, Russian wheat aphid.

A PEST never before seen in Western Australia has been detected on the south east coast of the State.

A sighting of Russian wheat aphid, which was discovered in South Australia in 2016 and subsequently in Victoria, parts of New South Wales and Tasmania, has been confirmed in two wheat crops north of Esperance.

Grain growers and consultants have been urged to survey cereal crops and grassy weeds for aphids and report any activity.

As it is difficult to distinguish between aphid species, landholders and consultants are encouraged to report all aphid activity via the Department of Primary Industries and Regional Development’s (DPIRD) MyPestGuide Reporter app.

DPIRD chief plant biosecurity officer Sonya Broughton said they had been working with industry to ensure it was well prepared in the event the pest was found in WA.

“Department officers have been working with stakeholders and the broader research community across Australia over several years to minimise the impact of this pest, as it has become broadly established across Australia,” Dr Broughton said.

“A lot has been learned from the research and growers’ experiences interstate about how cereal crops respond to Russian wheat aphid and how best to manage the pest.

“Crop monitoring by landholders and delimiting surveillance by the department will help us to determine the extent of spread of the pest in WA and what actions are required.”

The National Management Group, comprising all Australian governments, Grain Producers Australia and Plant Health Australia, determined in 2016 that the pest was not technically feasible or cost-beneficial to eradicate from Australia.

Eradication in WA is unlikely due to the biology of the pest and its ability to spread on the wind.

The crops where the detection was made will be sprayed to contain the pest, while further surveillance is undertaken.

Dr Broughton said inspecting the edges of wheat, barley and oat crops, where pests often colonise first, or where plants are under stress and looking for damage near the base of newly emerged leaves was most effective.

“Symptoms could look like herbicide, thrips, mite or wheat streak damage,” she said.

“Look for a noticeable loss of green colouration across the crop and, on closer inspection, white, yellow, purple or red streaking, leaf curling, stunted plant growth and loss of vigour.”

As Russian wheat aphids are only about two millimetres long, pale yellowish green with a fine waxy coating, a hand lens or smartphone macro lens may be useful.

Chemical permits are available to control Russian wheat aphids in grains crops, with more information available from the Australian Pesticides and Veterinary Medicines Authority’s website.

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The Economist

A plague of insects
Why locusts swarm

A new discovery could offer novel ways of controlling the insectsScience & technologyAug 15th 2020 edition


Aug 15th 2020

  • In some parts of the world, covid-19 is not the only plague that 2020 has brought. In parts of Asia and east Africa, swarms of locusts have stripped fields. The un reckons the swarms in India and Pakistan are the largest for a quarter of a century, and that the numbers in Kenya are the highest for 70 years. One swarm in northern Kenya was estimated to be 25 miles (40km) long and 37 miles wide.

Locusts are usually inoffensive, solitary creatures that do not stray far from the place that they were born. But under the right circumstances—namely heavy rain, and a subsequent boom in plant growth—they can become “gregarious”. When that happens the insects change colour and gather in ravenous swarms which can fly more than 100km in a day.

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Smithsonian Takes a Look at the World’s Most Interesting Insects

By Jessica Stewart on July 20, 2020

  • My Modern Net

Representing 80% of all animal species, insects are some of the most abundant animals on Earth. And yet, there is so much that your average person doesn’t know about these fascinating creatures. Thankfully, Smithsonian has taken it upon itself to highlight some of the most fascinating examples of these colorful animals with the Smithsonian Handbook of Interesting Insects.

Each insect was selected from the 34 million specimens located in London’s Natural History Museum. Over one hundred of the most significant bugs were chosen to get a full photographic layout accompanied by a short description. The book was curated by entomologists Gavin Broad, Blanca Huertas, Ashley Kirk-Spriggs, and Dmitry Telnov, who worked tirelessly to showcase a wide range of interesting insects.

“Our hope is that by drawing attention to some of the amazing variety of insect life, people will appreciate a bit more the explosion of color and form at the tiny scale,” shares Gavin Broad, who is the principal curator in charge of insects at the Natural History Museum. “And that acting to conserve the natural world will help ensure this diversity of life continues to thrive forever, rather than only being known from old museum specimens.”

Selections include the Claudina butterfly, whose crimson wings are beautiful in their own right but are nothing compared to the surprise of its underwings. Splashed with bright fuchsia and violet patches, this explosion of color is complemented by yellow tufts called the androconia. These are used to release pheromones that become vital in courtship.

Color is also on display when looking at a large African insect known as the Green milkweed grasshopper. Its rainbow-hued hind wings are typically hidden away when at rest, but are used when needed to scare off predators. And beware, when startled, it releases a  noxious fluid from its thorax that is derived from the poisonous plants it feeds on.

These are just some of the wasps, moths, beetles, and butterflies that are included in the Smithsonian guide. Filled with scientific information, but written to be accessible, it’s the perfect book for any insect lover.

Smithsonian Handbook of Interesting Insects is a guide to the world’s most fascinating bugs.

Claudina Butterfly

Claudina ButterflyPapuan Green Weevil

Papuan Green Weevilhttps://e9ce1564218607c73b1cc5d041a9f7d6.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.htmlOrchid Cuckoo Bee

Orchid Cuckoo BeeFlatid Planthopper

Flatid Planthopperhttps://e9ce1564218607c73b1cc5d041a9f7d6.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.htmlBrazilian Jewel Beetle and Darkling Beetle

Left: Brazilian Jewel Beetle | Right: Darkling Beetle

All images via the London Natural History Museum. My Modern Met granted permission to feature photos by Smithsonian Books.

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Man Turns His Fear of Bugs Into an Award-Winning Career as a Macro Insect Photographer

JESSICA STEWART

Jessica Stewart is a Contributing Writer and Digital Media Specialist for My Modern Met, as well as a curator and art historian. She earned her MA in Renaissance Studies from University College London and now lives in Rome, Italy. She cultivated expertise in street art which led to the purchase of her photographic archive by the Treccani Italian Encyclopedia in 2014. When she’s not spending time with her three dogs, she also manages the studio of a successful street artist. In 2013, she authored the book ‘Street Art Stories Roma‘ and most recently contributed to ‘Crossroads: A Glimpse Into the Life of Alice Pasquini‘. You can follow her adventures online at @romephotoblog.Read all posts from Jessica StewartFASCINATED BY BUGS?  SHARELIKE MY MODERN MET ON FACEBOOK https://www.facebook.com/v2.6/plugins/like.php?action=like&app_id=127840663940988&channel=https%3A%2F%2Fstaticxx.facebook.com%2Fx%2Fconnect%2Fxd_arbiter%2F%3Fversion%3D46%23cb%3Df288e6c3345f668%26domain%3Dmymodernmet.com%26origin%3Dhttps%253A%252F%252Fmymodernmet.com%252Ff27d6f080cd4da8%26relation%3Dparent.parent&container_width=555&href=https%3A%2F%2Fwww.facebook.com%2Fmymodernmet%2F&layout=button_count&locale=en_US&sdk=joey&share=true&show_faces=false GET OUR WEEKLY NEWSLETTER

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JULY 20, 2020

Returning to farming’s roots in the battle against the ‘billion-dollar beetle’

by University of Arizona

Returning to farming's roots in the battle against the 'billion-dollar beetle'
Western corn rootworm larvae can devour the tips of corn roots, robbing the plants of nutrients and making them susceptible to falling over. Credit: Cyril Hertz, Lingfei Hu and Matthias Erb, University of Bern, Switzerland

Nicknamed the “billion-dollar beetle” for its enormous economic costs to growers in the United States each year, the western corn rootworm is one of the most devastating pests farmers face.https://3777ec3032f89ac36b1a5fe5c7568749.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

“They are quite insidious. They’re in the soil gnawing away at the roots and cutting off the terminal ends of the roots—the lifeblood of corn,” said Bruce Tabashnik, Regents Professor and head of the University of Arizona Department of Entomology. “And if they’re damaging enough, the corn plants actually fall over.”

Genetically modified crops have been an important tool in the battle against pests such as these, increasing yields while reducing farmers’ reliance on broad-spectrum insecticides that can be harmful to people and the environment.

Corn was genetically engineered to produce proteins from the bacterium Bacillus thuringiensis, or Bt, that kill rootworm larvae but are not toxic to humans or wildlife. The technology was introduced in 2003 and has helped keep the corn rootworm at bay, but the pest has begun to evolve resistance.

“So, now the efficacy of this technology is threatened and if farmers were to lose Bt corn, the western corn rootworm would become a billion-dollar pest again,” said Yves Carrière, a professor of entomology in the College of Agriculture and Life Sciences.

Crop Rotation in Mitigating Pest Resistance

Carrière is lead author of a study to be published in PNAS that evaluated the effectiveness of crop rotation in mitigating the damage caused by resistant corn rootworms. Tabashnik and colleagues from North Carolina State University, the University of California-Davis, McGill University and Stockholm University coauthored the study.

Crop rotation, the practice of growing different crops in the same field across seasons, has long been used for pest control. In 2016, the U.S. Environmental Protection Agency mandated crop rotation as a primary means of reducing the damage to Bt corn fields caused by resistant corn rootworms, but there have been limited scientific studies to support the efficacy of this tactic.https://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-0536483524803400&output=html&h=280&slotname=5350699939&adk=2265749427&adf=625945176&w=750&fwrn=4&fwrnh=100&lmt=1595996918&rafmt=1&psa=1&guci=2.2.0.0.2.2.0.0&format=750×280&url=https%3A%2F%2Fphys.org%2Fnews%2F2020-07-farming-roots-billion-dollar-beetle.html&flash=0&fwr=0&rpe=1&resp_fmts=3&wgl=1&dt=1595996918602&bpp=11&bdt=88&idt=147&shv=r20200727&cbv=r20190131&ptt=9&saldr=aa&abxe=1&cookie=ID%3Dfd49ee1f356c7aad-2230268791c20026%3AT%3D1595996908%3AS%3DALNI_MZ__AIkhsEMsw1AjrlZUCXlh_wvFw&correlator=2622896222429&frm=20&pv=2&ga_vid=683244895.1595996911&ga_sid=1595996919&ga_hid=1573871060&ga_fc=0&iag=0&icsg=2271232&dssz=26&mdo=0&mso=0&u_tz=-300&u_his=2&u_java=0&u_h=1080&u_w=1920&u_ah=1040&u_aw=1920&u_cd=24&u_nplug=3&u_nmime=4&adx=447&ady=2184&biw=1903&bih=969&scr_x=0&scr_y=0&oid=3&pvsid=1003068873479674&pem=0&rx=0&eae=0&fc=896&brdim=0%2C0%2C0%2C0%2C1920%2C0%2C1920%2C1040%2C1920%2C969&vis=1&rsz=%7C%7CpeEbr%7C&abl=CS&pfx=0&fu=8320&bc=31&ifi=1&uci=a!1&btvi=1&fsb=1&xpc=7ptrOeJu1R&p=https%3A//phys.org&dtd=154

Carrière and his team rigorously tested this approach by analyzing six years of field data from 25 crop reporting districts in Illinois, Iowa and Minnesota—three states facing some of the most severe rootworm damage to Bt cornfields.

The results show that rotation works. By cycling different types of Bt corn and rotating corn with other crops, farmers greatly reduced rootworm damage.

Most notably, crop rotation was effective even in areas of Illinois and Iowa where rootworm resistance to corn and soybean rotation had been previously reported.

According to the study, crop rotation provides several other benefits as well, including increased yield, reductions in fertilizer use and better pest control across the board.

“Farmers have to diversify their Bt crops and rotate,” Carrière said. “Diversify the landscape and the use of pest control methods. No one technology is the silver bullet.”

Returning to farming's roots in the battle against the 'billion-dollar beetle'
Western corn rootworm beetle on corn tassels. Credit: Joseph L. Spencer, Illinois Natural History Survey, University of Illinois at Urbana-Champaign

A Multipronged Approach

Tabashnik relates the research back to UArizona’s work with the pink bollworm, in which researchers spearheaded a management program to suppress the pink bollworm’s resistance to Bt cotton.

“The key to eradicating pink bollworm in the U.S. was integrating Bt cotton with other control tactics,” Tabashnik said. “We succeeded, whereas this voracious invasive pest rapidly evolved resistance to Bt cotton in India, where the genetically engineered crop was used alone.”

In collaboration with cotton growers, UArizona scientists sustained the efficacy of Bt cotton against pink bollworm by establishing the “refuge strategy,” in which non-Bt crops are planted near Bt crops to allow survival of susceptible insects. The strategy has become the primary approach used worldwide to delay the adaptation of insect pests to genetically engineered crops.

Although farmers have used refuges to thwart the rootworm’s resistance to Bt corn, this strategy alone has proven insufficient against the pest.

“During the last decade, we have learned that refuges are often not sufficient to delay resistance in pests like the corn rootworm,” Carrière said. “It would be wise to diversify management tactics before such pests evolve resistance. This approach, called integrated pest management, is vital for preserving the benefits of biotechnology.”

Returning to Agricultural Roots

In many ways, the study reaffirms traditional agricultural knowledge.

“People have been rotating crops since the dawn of farming. The new agricultural technology we develop can only be sustained if we put it in the context of things we’ve known for thousands of years,” Tabashnik said. “If we just put it out there and forget what we’ve learned in terms of rotating crops, it won’t last.”

The authors emphasize that increasing crop rotation is essential for sustaining the economic and environmental benefits provided by rootworm-active Bt corn. During the six years of the study, the average percentage of corn rotated to other crops per state ranged from about 55-75%.

“This is one of the most important applications of Bt crops in the United States,” Carrière said. “If we lose this technology and we start using soil insecticides again, it’s going to have a big negative environmental impact.”


Explore furtherScientists offer recommendations for delaying resistance to Bt corn in western corn rootworm


More information: Crop rotation mitigates impacts of corn rootworm resistance to transgenic Bt corn, PNAS (2020). DOI: 10.1073/pnas.2003604117Journal information:Proceedings of the National Academy of SciencesProvided by University of Arizona

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NEWS RELEASE 20-JUL-2020

Portable DNA device can detect tree pests in under two hours

New method tests for harmful species like the Asian gypsy moth and sudden oak death pathogen

UNIVERSITY OF BRITISH COLUMBIASHARE PRINT E-MAIL

IMAGE
IMAGE: UBC PROFESSOR RICHARD HAMELIN INSPECTING A GYPSY MOTH TRAP view more CREDIT: PAUL H JOSEPH/UBC

Asian gypsy moths feed on a wide range of important plants and trees. White pine blister rust can kill young trees in only a couple of years. But it’s not always easy to detect the presence of these destructive species just by looking at spots and bumps on a tree, or on the exterior of a cargo ship.

Now a new rapid DNA detection method developed at the University of British Columbia can identify these pests and pathogens in less than two hours, without using complicated processes or chemicals – a substantial time savings compared to the several days it currently takes to send samples to a lab for testing.

“Sometimes, a spot is just a spot,” explains forestry professor Richard Hamelin, who designed the system with collaborators from UBC, Natural Resources Canada and the Canadian Food Inspection Agency. “Other times, it’s a deadly fungus or an exotic bug that has hitched a ride on a shipping container and has the potential to decimate local parks, forests and farms. So you want to know as soon as possible what you’re looking at, so that you can collect more samples to assess the extent of the invasion or begin to formulate a plan of action.”

Hamelin’s research focuses on using genomics to design better detection and monitoring methods for invasive pests and pathogens that threaten forests. For almost 25 years, he’s been looking for a fast, accurate, inexpensive DNA test that can be performed even in places, like forests, without fast Internet or steady power supply.

He may have found it. The method, demonstrated in a preview last year for forestry policymakers in Ottawa, is straightforward. Tiny samples like parts of leaves or branches, or insect parts like wings and antennae, are dropped into a tube and popped into a small, battery-powered device (the Franklin thermo cycler, made by Philadelphia-based Biomeme). The device checks to see if these DNA fragments match the genomic material of the target species and generates a signal that can be visualized on a paired smartphone.

“With this system, we can tell with nearly 100 per cent accuracy if it is a match or not, if we’re looking at a threatening invasive species or one that’s benign,” said Hamelin. “We can analyze up to nine samples from the same or different species at a time, and it’s all lightweight enough–the thermocycler weighs only 1.3 kilos–to fit into your backpack with room to spare.”

The method relies on PCR testing, the method that is currently also the gold standard for COVID-19. PCR testing effectively analyzes even tiny amounts of DNA by amplifying (through applying heating and cooling cycles) a portion of the genetic material to a level where it can be detected.

Hamelin’s research was supported by Genome Canada, Genome BC and Genome Quebec and published in PLOS One. The UBC team, including lead author Arnaud Capron, tested this approach on species such as the Asian gypsy moth, white pine blister rust and sudden oak death pathogen, which are listed among the most destructive invasive pests worldwide.

“Our forestry, agriculture and horticulture are vital industries contributing billions of dollars to Canada’s economy so it’s essential that we protect them from their enemies,” added Hamelin. “With early detection and steady surveillance, we can ensure that potential problems are nipped, so to speak, in the bud.”

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science daily

Gene-editing protocol for whitefly pest opens door to control

Date:
April 23, 2020
Source:
Penn State
Summary:
Whiteflies are among the most important agricultural pests in the world, yet they have been difficult to genetically manipulate and control, in part, because of their small size. An international team of researchers has overcome this roadblock by developing a CRISPR/Cas9 gene-editing protocol that could lead to novel control methods for this devastating pest.
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Whiteflies are among the most important agricultural pests in the world, yet they have been difficult to genetically manipulate and control, in part, because of their small size. An international team of researchers has overcome this roadblock by developing a CRISPR/Cas9 gene-editing protocol that could lead to novel control methods for this devastating pest.

According to Jason Rasgon, professor of entomology and disease epidemiology, Penn State, whiteflies (Bemisia tabaci) feed on many types of crop plants, damaging them directly through feeding and indirectly by promoting the growth of fungi and by spreading viral diseases.

“We found a way to genetically modify these insects, and our technique paves the way not only for basic biological studies of this insect, but also for the development of potential genetic control strategies,” he said.

The team’s results appeared on April 21 in The CRISPR Journal.

The CRISPR/Cas9 system comprises a Cas9 enzyme, which acts as a pair of ‘molecular scissors’ that cuts DNA at a specific location on the genome so bits of DNA can be added or removed, and a guide RNA, that directs the Cas9 to the right part of the genome.

“Gene editing by CRISPR/Cas9 is usually performed by injecting the gene-editing complex into insect embryos, but the exceedingly small size of whitefly embryos and the high mortality of injected eggs makes this technically challenging,” said Rasgon. “ReMOT Control (Receptor-Mediated Ovary Transduction of Cargo), a specific type of CRISPR/Cas9 technique developed in my lab, circumvents the need to inject embryos. Instead, you inject the gene-editing complex which is fused to a small ovary-targeting molecule called BtKV, into adult females and the BtKV guides the complex into the ovaries.”

To explore the use of ReMOT Control in whiteflies, the team targeted the “white” gene, which is involved in eye color. When this gene is functioning normally, whiteflies have brown eyes, but when it is non-functional due to mutations, the insects is supposed to have white eyes. The team found that ReMOT Control generated mutations that resulted in juvenile insects with white eyes that turned red as they developed into adults.

“Tangentially, we learned a bit about eye color development,” said Rasgon. “We expected the eyes to remain white and were surprised when they turned red. Importantly, however, we found that the mutations we generated using ReMOT Control were passed on to offspring, which means that a change can be made that is inherited to future generations.”

Rasgon said the team hopes its proof-of-principle study will allow scientists to investigate the same strategy using genes that affect the ability for the insects to transmit viral pathogens of crop plants to help control the insects and protect crops.

“This technique can be used for any application where you want to delete any gene in whiteflies, for basic biology studies or for the development of potential genetic control strategies,” he said.


Story Source:

Materials provided by Penn State. Note: Content may be edited for style and length.


Journal Reference:

  1. Chan C. Heu, Francine M. McCullough, Junbo Luan, Jason L. Rasgon. CRISPR-Cas9-Based Genome Editing in the Silverleaf Whitefly (Bemisia tabaci). The CRISPR Journal, 2020; 3 (2): 89 DOI: 10.1089/crispr.2019.0067

Cite This Page:

Penn State. “Gene-editing protocol for whitefly pest opens door to control.” ScienceDaily. ScienceDaily, 23 April 2020. <www.sciencedaily.com/releases/2020/04/200423130410.htm>.

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The Heartland Institute

Genetically Engineered Moths Could Eliminate Crop Pests

April 23, 2020

But farmers might soon be getting a new weapon to combat them: Genetically engineered versions of the moths that mate with wild pests and cause half their offspring to die.

 

Diamondback moths can wipe out entire fields of crops and ruin farmers. They’re also the pests most resistant to insecticides and crops genetically modified to kill them. Farmers, however, might soon be getting a new weapon to combat them: genetically engineered versions of the moths that mate with wild pests and cause half their offspring to die—but that will happen only if federal regulators significantly speed up their approval process.

The biotechnology company Oxitec developed the modified diamondback moths, which survive well on actual farms. Once modified males mate with females in the wild, where their “lethality” gene is passed along, the gene prevents the female offspring from developing, so they die as larvae.

Meanwhile, the male offspring survive with half inheriting the “lethality” gene. The population shrinks further when those males grow up and mate with other wild females, causing the next generation of female offspring to die as well.

Resistant to Pesticides

The diamondback moth is the number one insect in the world for resistance to pesticides, says Alton Sparks, professor of entomology at The University of Georgia.

“Everything that has been tried to control diamondback moths, they have developed a resistance to,” said Sparks. “We have populations in south Georgia that we are unable to control with insecticides.”

Sparks says the pests are very particular about what they feed on: vegetables that thrive in cold or cool weather, such as broccoli, cabbage, canola, cauliflower, collards, and kale, resulting in billions of dollars in lost crops each year.

“They chew holes in the leaves while they’re a caterpillar,” Sparks said . “You can lose an entire field because they make the crops unmarketable.”

Species-Specific

It will take a while for the technology to truly cut down diamondback moth populations, says Sparks.

“You can’t put the modified moths out there and then spray pesticides, because you might interfere with modified moths being released,” said Sparks. “There will be a learning curve, but it’s something we can establish as the population limits itself, and we will have to work with the population for a while before it overcomes the wild population and causes it to crash.”

The Oxitec technology is species-specific, so it will not impact non-target species, says Sparks.

“If it works the way we hope it will, then it replaces fairly heavy pesticide use,” Sparks said. “There may be some concerns because it involves genetic modification of the insect, but it is not something that’s going to end up contaminating or damaging the food supply or the environment, and the modification doesn’t affect other species.

“If this species becomes extinct, it would make crop production much easier and reduce chemical use,” said Sparks. “The diamondback moth is a worldwide pest. I’ve been studying it for the past 32 years, and it’s unfortunate this technology is years away from being commercially available,” because of the long delays awaiting approval by federal regulators.

‘An Unalloyed Good’

If the GMO diamondback moth works as designed, it would be a pure good for agriculture, the environment, and society, says Gregory Conko, a senior fellow at the Competitive Enterprise Institute.

“If successful, modified diamondback moths would represent an unalloyed good: a boon to farmers, food production, and the environment,” said Conko. “It is always good when farmers have another tool to help them fight pests, because globally it’s estimated they lose between 20 and 40 percent of their crop potential to pests.

“The number is closer to the lower end of the range in industrialized countries like the United States, but a technology like this can easily be used in other parts of the world, and no matter where you are, less crop loss to pests means more food, lower prices paid by consumers, and fewer resources needed to produce a given amount of food,” Conko said.

“In addition, although chemical spray insecticides can be used safely—meaning, with little risk to humans—and though they can be used in a way to minimize the impact on nature, a crop protection technology like this, narrowly targeted to impact only the pest species, is especially welcome because it will have very low risk of effects on non-target organisms, allowing farmers to control diamondback moths with essentially zero unintended side effects,” Conko said.

Regulations Likely to Slow Introduction

The biggest remaining hurdles to commercial introduction of the GMO moth are regulatory, says Conko.

“Theoretically, we could be relatively close to commercialization, because the genetically engineered moths have been studied over multiple generations in the closed environment of a greenhouse, with very promising results, and a recent field study [published in the journal Frontiers in Bioengineering and Biotechnology] showed positive results as well,” Conko said. “Naturally, you’d like to study the impacts in the field over a couple of additional years to make sure the technology works and lasts over the long run, and to ensure there are no unintended side effects, meaning under normal circumstances, the GMO diamondback moth could be ready for commercial release in three to four years, tops.

“The biggest hurdles to commercialization are not likely to be related to the technology working safely, but due to regulations, because even after extensive safety testing, federal regulators will likely take several additional years before making a decision as to whether the technology can be released commercially,” Conko warns. “As a result it would not be unrealistic to think it could take over a decade before the Oxitec’s modified moth reaches the marketplace.”

Kenneth Artz (kennethcharlesartz@gmx.com) writes from Dallas, Texas.

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Delta f perss

A bollworm chows down on a cotton plant University of Arkansas System Division of Agriculture/Aaron Cato
A bollworm chows down on a cotton plant in this photo taken July 22, 2017.

Bollworms could be ‘budget buster’ for some Arkansas cotton growers

Worries over growing bollworm populations are amplified by possible resistance to dual gene technology.

Sarah Cato | Jul 23, 2018

“The bollworm pressure is decidedly higher than what we’ve seen in the last couple years,” said Gus Lorenz, Extension entomologist for the University of Arkansas System Division of Agriculture. “We’re seeing an extremely high number of eggs and moths in cotton fields. We’re kicking up hundreds and hundreds of moths in fields.”

The flights have been merciless this growing season, without much of a break.

“Flights have continued since June and haven’t let up,” Lorenz said. “We call these rolling populations, they just keep coming.”

Although only certain areas of Arkansas are currently affected, that could change.

“Some parts of the state aren’t having this problem,” Lorenz said. “We’re seeing this in the south and central part of Arkansas and along the Louisiana line. But we’re seeing indications that it will roll up to north central and possibly northeast Arkansas.”

Lorenz’s biggest concern with this year’s bollworm pressure is the resistance to dual gene cotton recent data has shown.

“Our concern is where we documented last year is the developing resistance to dual gene cotton,” Lorenz said. “We’re seeing more eggs and larvae developing in dual gene cotton, and it’s got us on edge.”

Dual gene technology refers to cotton varieties that have two Bt genes, which are used to protect against multiple insect pests, including bollworm.

Lorenz is alerting growers that not controlling these tremendous bollworm populations in cotton will be detrimental to the success of their crop.

When Bt genes are failing to control bollworm populations, an egg threshold of 25 percent is generally used, meaning producers should treat when 25 percent of plants have eggs in terminals or bloom tags. However, some Arkansas cotton fields are seeing numbers well beyond that.

“We’re not just seeing 25 percent or 40 percent, we’re talking about multiple eggs per plant,” he said. “Growers are going to see resulting damage and how they manage this is going to make a difference.

Control options

As far as management practices go, many Arkansas cotton producers have already taken control measures, but they’re getting hit again.

“There are a lot of concerned growers that made an application seven to 10 days ago of a diamide, like Prevathon or Besiege, to get the bollworms under control, but now there’s a new flight,” Lorenz said.

Although there is a growing concern for the damage these pests can cause, Lorenz warns against going overboard with treatment applications.

“We’re advising growers to give it two weeks before making a second application of a diamide,” he said. “Usually residual control will last at least two weeks, maybe more. Those products are extremely expensive and I can’t see making a second application this soon. That could be a budget buster.”

There are more control options that will allow cotton producers to avoid making a second diamide application too soon.

“In the meantime, use a pyrethroid plus acephate and try to knock down those high numbers in those areas,” Lorenz said. “These applications can knock down those moth populations.”

Arkansas cotton producers are at risk with these current bollworm numbers, and Lorenz is warning everyone to scout their fields.

“Be diligent because this is a very critical time for cotton and soybeans,” Lorenz said. “Scout and scout hard. In the immediate future we will continue to see the development of bollworm populations.”

Management options can be found at: https://www.uaex.edu/publications/pdf/mp144/mp144.pdf

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CABI- The Invasives Blog

Fight against fall armyworm in Kenya ‘mobilised’ with new government text messaging campaign

FAW text

A new weapon in the fight against the fall armyworm caterpillar in Kenya is being launched giving thousands of smallholder farmers free expert help and advice on how to tackle the devastating pest through mobile SMS text messaging.

Precision Agriculture for Development (PAD) has joined forces with the Ministry of Agriculture and Irrigation (MAI), Safaricom, and CABI to provide the service, called ‘MoA-INFO’, to maize farmers throughout the country.

MoA-INFO was designed and developed in collaboration with the MAI Plant Protection Services Division and various Government agencies including the Pest Control Products Board (PCPB), the Kenya Plant Health Inspectorate Service (KEPHIS), the Agriculture Information Resource Centre (AIRC), and the Kenya Agricultural and Livestock Research Organisation (KALRO).

To date, there is no defined method of eradicating fall armyworm. However, a number of non-chemical and chemical methods can be used to control the spread of fall armyworm and limit losses. The new SMS information service aims to share information about these control measures as well as other important advice that all maize farmers can use to manage the pest.

MoA-INFO will give maize farmers up-to-date information on the pest, including how to identify it, determine its level of infestation, and various control methods, before offering recommendations about other crops affected by fall armyworm, other pests and other agricultural topics. The objective of the SMS platform is to provide a comprehensive extension service to all farmers in the country free of charge.

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Such information will guide farmers with sound fall armyworm management measures, thereby contributing towards the overall Government agenda on 100% food security. Maize is the staple food for approximately 80% of the Kenyan population. Any efforts towards control of fall army worm, an insect with potential to cause up to 100% yield losses is important. In the main 2017 maize cropping season, deployment of various management measures helped to reduce fall armyworm maize yield reduction to a national average of 20% from the 100% expected.

MoA-INFO is currently available to all Safaricom customers for free. It will soon be available to Airtel customers for free too. All a farmer needs to do is to send an SMS message with the word “SHAMBA” (for messages in Kiswahili) or “FARM” (for messages in English) to 40130. Sending and receiving SMS messages is free.

The MoA-INFO service has already been piloted in Western Kenya successfully. Derrick Ooko, a farmer from Matayos South, said, “This story of fall armyworm is a big challenge in Busia County, mostly to small scale farmers. The information that I have received from MoA-INFO SMS has greatly assisted me to know how to manage the pest. I agree information is power and I am very grateful.”

PAD is running and managing the MoA-INFO SMS information service with approval of the Government and other development partners.

“It is my hope this SMS mobile service, will reach millions of farmers in Kenya. They will access for free guidance in the fight against fall armyworm, which will ultimately improve livelihoods and national food security”, says Emmanuel Bakirdjian, PAD’s Kenya Country Director.

The Ministry of Agriculture and Irrigation acknowledges the support of Precision Agriculture for Development (PAD) in the development and implementation of this innovative methodology of disseminating information to farmers. This service has created a platform to leverage on use of mobile phones to bridge the gap of reaching all farmers in the country with extension messages on this devastating pest.

Find out more about this pest on CABI’s fall armyworm resource page→

 

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