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New crop-destroying locust swarms hitting East Africa ‘nearly every day,’ UN warns in renewed call to fight major food security threat

United Nations | January 21, 2021

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Credit: AP
Credit: AP

This article or excerpt is included in the GLP’s daily curated selection of ideologically diverse news, opinion and analysis of biotechnology innovation.

Dominique Burgeon, FAO’s [the UN’s Food and Agriculture Organization] Director of Emergencies and Resilience, said the huge [African] desert locust swarms in 2020, some as wide as 60 kilometers, had not been seen in decades, threatening food security in a region where many were already going hungry. 

Surveillance and response led to 1.6 million hectares of land being treated.  As a result, more than three million tonnes of cereals, valued at approximately $940 million, were protected: enough to feed 21 million people for a year. 

“We can say that huge progress has been made, capacities of the countries have been tremendously augmented…but yet the situation is not over”, he told journalists. “We have made a huge effort, we are much better prepared, but we should not be complacent. We should not relax.”  

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With neighboring countries battling crop-ravaging locusts, Zimbabwe readies itself for potential outbreak

Sifelani Tsiko | Zimbabwe Herald | January 22, 2021

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Credit: National Geographic
Credit: National Geographic

This article or excerpt is included in the GLP’s daily curated selection of ideologically diverse news, opinion and analysis of biotechnology innovation.

Shingirai Nyamutukwa, head of the [Zimbabwe] Plant Quarantine and Plant Protection Research Services Institute [January 17] said there was an alert following reports of a new round of locust outbreaks.

“Yes, it’s true that Namibia and Botswana are battling another wave of locust outbreaks. The locusts are in all stages from nymphs to adults. We’re keeping check on their control efforts so as to assess risks of invasion into Zimbabwe,” he said.

Last year, locust outbreaks in Zimbabwe, Botswana, Namibia and Zambia were controlled.

Heavy rains have created conducive conditions for swarms to breed in these countries, forcing plant protection agencies to take steps to control any outbreaks.

SADC and partner organisations like International Red Locust Control Organization for Central and Southern Africa (IRLCO-CSA) were working with the four countries to control the pest and protect people’s livelihoods.Follow the latest news and policy debates on agricultural biotech and biomedicine? Subscribe to our newsletter.SIGN UP

In Namibia and Botswana, the plant protection expert said, some other types of locusts are emerging besides the African migratory locust owing to the wet weather which create favorable factors for all these insects to multiply.

“With a lot of food available due to good rains, we expect the region to have a [difficult time fighting] locust outbreaks throughout the last half of the season,” Nyamutukwa said.

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East Africa gets ready for return of destructive locust swarms

In 2020, East Africa was struck by the worst locust plague in decades. Unfortunately, now, the swarms are returning.

The locusts invading East Africa last year ravaged crops and pastures and drove the levels of hunger and economic hardship higher in parts of the region. One year later, right at the start of 2021, the United Nations has warned that a second and maybe even deadlier return of locusts has already begun.

The first wave of the pests emerged at the end of 2019, numbering in hundreds of billions, multiplying by a factor of 20 per generation, according to the UN Food and Agriculture Organization (FAO). The second generation in March and April numbered in the trillions. A plague that spread like wildfire — up to now.

Image: FAO / DUS

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“It’s a continuation of the 2020 locusts swarm. The adults have flown to various areas and are laying eggs”, Frances Duncan, Professor of Animal, Plant & Environmental Sciences at the University of the Witwatersrand, told DW. “If we have good rains like it is the case at the moment in most areas, the hoppers will hatch, and we get the second wave of the swarm.”

However, Keith Cressman, FAO’s Senior Locust Forecasting Officer, remains optimistic. “I think it’s still a very dangerous situation. But it should not be worse as it was last year.” According to the weather forecast, the months to come should be dry, reducing the locusts’ reproductive rate.

Publication date: Wed 6 Jan 2021

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Fightback starts against fall armyworm

Published Yesterday at 09:35 AM

Minister for Agricultural Industry Development and Fisheries and Minister for Rural Communities
The Honourable Mark Furner

The Queensland Department of Agriculture and Fisheries (DAF) has received approval to import a biopesticide for research purposes, marking a significant step in the fight to combat fall armyworm (FAW).

Minister for Agricultural Industry Development and Fisheries and Minister for Rural Communities Mark Furner said the Federal Department of Agriculture, Water and the Environment (DAWE) approval to import Fawligen® meant the Queensland Government could start working on management packages for impacted industries.

“Since the initial detection of FAW in Australia in January 2020, DAF has worked closely with industry to find ways to address the threat posed by this voracious invasive pest to Queensland’s agriculture industry,” Mr Furner said.

“Fawligen® is a biopesticide targeting the FAW caterpillar which ingests virus particles, becomes infected and dies, spreading the virus to other FAW larvae in the crop.

“DAF first applied in March 2020 to bring Fawligen®, which is produced in the US by Australian company AgBiTech, into Australia.

“Getting DAWE’s approval to import Fawligen®, a naturally occurring caterpillar virus which targets FAW, is a key step forward as it has the potential to be a game changer for producers.”

Mr Furner said having access to Fawligen® would allow DAF researchers to immediately commence small scale work with AgBiTech to assess its performance on FAW populations, under local conditions and in various crops. 

“This will generate information for an Australian Pesticides and Veterinary Authority (APVMA) regulatory submission,” Mr Furner said.

“Natural biological control agents, like Fawligen®, reduce grower reliance on conventional insecticides for FAW control, reducing the risk of insecticide resistance development.

“Another significant advantage of this biopesticide is that it only kills the FAW and is non-toxic to beneficial organisms including honeybees and beneficial natural enemies such as spiders, wasps and ladybeetles.”

AgBiTech’s General Manager for Australia, Philip Armytage, said in response to the spread and rise of FAW as a global pest, in 2015 AgBiTech established a production facility in the US to manufacture Fawligen® for Brazil and other global markets.

“At the time, Fawligen® could not be produced in Australia as the FAW was not present,” Mr Armytage said.

“Globally, Fawligen® is AgBiTech’s biggest product by volume, and we are excited to be able to bring our technology back home to Australia for our farmers.

“We will accelerate the project, working closely with DAF and use all our international experience to support the commencement of the registration work as soon as possible.”

Mr Furner said DAF had a long history of working closely with AgBiTech in supporting the development of the Helicoverpa biocontrol ViVUS Max® in the early 2000s. 

“Australia is the global leader in the use of native and introduced biocontrol agents,” he said.

“We have seen excellent results in the control of similar caterpillar pests such as Helicoverpa as well as with silverleaf whitefly and prickly pear.

“In the meantime, growers should remain vigilant for the presence of FAW and check for the latest insecticide permits applying to fall armyworm using the APVMA’s permit portal.”

The latest advice about the impacts and management of fall armyworm on key crops can be found on the fall armyworm web page at business.qld.gov.au/fallarmyworm.

ENDS

Minister Furner media contact:                   Ron Goodman            0427 781 920

AgBiTech / Fawligen media contact:         Philip Armytage          0488 263585

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Management of Fall Armyworm: The IPM Innovation Lab Approach

https://ipmil.cired.vt.edu/wp-content/uploads/2020/12/IPM-IL-FAW-Management.pdf.

By:

Sara Hendery

Communications Coordinator

Feed the Future Innovation Lab for Integrated Pest Management

Hendery, Sara saraeh91@vt.edu

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Science News from research organizations


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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