Archive for the ‘Insecticide resistance’ Category

A new study showed that by following action thresholds to determine when to apply insecticides to control onion thrips, farmers made 2.3 fewer applications per season while maintaining yields and bulb size.

NY onion growers can keep yields while cutting chemical use

By Sarah Thompson  Cornell Agritech

August 1, 2022FacebookTwitterEmailShare

A surprise finding from new research on controlling pests and disease in New York commercial onion fields will enable the state’s producers to cut their use of synthetic chemicals without sacrificing yield.

The study, conducted by scientists at Cornell AgriTech and recently published in the journal Agronomy on May 28, showed that by following action thresholds to determine when to apply insecticides to control onion thrips – a major annual pest – farmers made 2.3 fewer applications per season while maintaining yields and bulb size. Action threshold is the density of the pest in a crop that requires a control measure to prevent the population from increasing to a level that will cause economic loss.

The results of more than three years of field trials also showed that farmers could use 50 to 100% less fertilizer without reducing yields.

“Plots with no fertilizer had no difference [compared to plots with full and half amounts],” said Max Torrey ’13, whose 12th generation family farm in Elba, New York was a trial site for the study. “People were skeptical, but this evidence gives us a lot more confidence in what we need to use.”

Growing onions in the western New York climate requires intensive cultivation and heavy reliance on synthetic fertilizer and pesticides. It’s also done exclusively on muck soils – the dark, fertile footprints of drained swamps. New York farmers grow nearly all 7,000 acres of the state’s dry bulb onions on the muck.

Onions, an important staple in most kitchens, are the fourth most-consumed fresh vegetable in the U.S., behind potatoes, tomatoes and sweet corn. New York growers have an added advantage with this high value crop due to their close proximity to large markets along the Eastern seaboard. But the market varies widely year to year depending on conditions in other growing regions and demand. Diseases and pests, especially the onion thrips, also eat into New York growers’ profits.

The onion thrips—tiny, winged insects that feed on onion plants – have been on Brian Nault’s radar for years. Nault, the study’s senior author and professor of entomology at Cornell AgriTech, said farmers used to rely on cost-effective weekly insecticide spray programs to control thrips. Then, in the late 1990s, thrips began rapidly developing insecticide resistance, because five to eight generations can be produced per year. Thrips also transmit a virus that can kill onion plants and spread bacteria leading to bulb rot.

To help preserve the effectiveness of remaining insecticides, Nault has been fine-tuning action thresholds so New York onion growers can remain profitable while spraying only when pest populations require it.

“The No. 1 reason farmers give for using action thresholds is mitigating the development of insecticide resistance,” Nault says. “The next new, good chemical tool may not come until 2025. They can’t afford to lose this one.”

In his new study, Nault and postdoctoral researcher Karly Regan aimed to further hone their integrated pest management strategy for onion thrips. They knew growers who continued using weekly spray programs instead of action thresholds were taking a significant risk by increasing the likelihood of resistance developing. But Nault also found studies that showed reducing fertilizer amounts could potentially reduce pests in certain crops. He added the factor in test trials.

Nault and his grower partners were amazed to find that the amount of fertilizer applied to an onion at planting had no impact on thrips population levels, bulb rot, or on onion bulb size and yield.

“We didn’t expect this, but it has an even bigger potential impact,” Nault said. “Reducing fertilizer use in commercial farming is beneficial to the environment for so many reasons, especially water and soil health.”

If all New York onion growers used action thresholds, Nault says they’d see a cumulative annual savings of $420,000 in pesticide costs. Already, he’s seen many growers reduce their fertilizer use this year by between 25 and 50% – a major change from applying a blanket amount to every field. Scouting for thrips and soil sampling each year are a little more work, but Torrey says he anticipates saving at least $100 per acre in chemical costs on his 2,200 acres of onions, in addition to the ecological rewards.

“The muck is our livelihood and our future,” Torrey said. “We must take care of it. Now we finally have a proven way to reduce costs and make New York onion growers even more competitive and sustainable.”

This research was supported by a grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture and Specialty Crop Research Initiative.

Sarah Thompson is a writer for Cornell Agritech.

Food & Agriculture

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Winter Honey Bees Show Resistance to a Common Insecticide

USDA Agricultural Research Service sent this bulletin at 06/21/2022 09:45 AM EDT

View as a webpageARS News ServiceARS News ServiceHoney bees in large cages.
Honey bees feed on imidacloprid during a cage experiment. (Photo by Mohamed Alburaki, ARS)Winter Honey Bees Show Resistance to a Common InsecticideFor media inquiries contact: Jessica Ryan
June 21, 2022Winter honey bees, compared to newly emerged summer bees, have a better ability to withstand the harmful effects of a widely-used insecticide in pest management, according to a recent study published in Apidologie.United States Department of Agriculture (USDA), Agricultural Research Service (ARS) researchers from the Bee Research Laboratory in Beltsville, Maryland, found winter honey bees’ consumption of a nearly lethal, imidacloprid-laced syrup did not affect their survival during the study.Imidacloprid is an insecticide made to mimic nicotine and is toxic to insects. This powerful insecticide is widely used in agriculture for pest management control. Honey bees are likely to encounter imidacloprid while foraging in the field or through contaminated hive products.”Although imidacloprid toxicity to honey bees is an important concern for beekeepers, our results provide good news,” said Miguel Corona and Mohamed Alburaki, researchers at the ARS Bee Research Laboratory. “Our research shows that winter honey bees have unrecognized physiological mechanisms to counteract the effects of insecticides.”The study assessed differences in diet behaviors for summer and winter honey bees in a controlled laboratory setting. Researchers provided sublethal doses of the imidacloprid-laced syrup to bees as necessary. Winter bees showed a preference to consuming imidacloprid-laced syrup over untreated sugar syrup while summer honey bees made the safe choice and avoided consuming the laced syrup each time.According to Corona, it is important to study the differences of summer and winter honey bees’ diets.  Honey bee colonies survive extreme seasonal differences in temperature and forage by producing two seasonal phenotypes of workers: summer and winter bees. These seasonal phenotypes differ significantly in their psychological characteristics as well as their susceptibility to disease and ability to handle poisonous substances.”Winter bees and summer bees undergo physiological changes to cope with drastic seasonal changes in temperature and the availability of nutritional resources,” said Corona and Alburaki. “Our results suggest that long-lived winter bees are especially well-adapted to tolerate higher levels of chemical stressors.”Corona said that although the study’s results show that winter bees could tolerate more intoxication by imidacloprid, they are still susceptible to higher concentrations of this insecticide in field settings.The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $17 of economic impact.Interested in reading more about ARS research? Visit our news archiveU.S. DEPARTMENT OF AGRICULTURE
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FEBRUARY 18, 2022

‘Super pest’ Colorado potato beetle has the genetic resources to sidestep our attacks

by Eric Hamilton, University of Wisconsin–Madison

‘Super pest’ Colorado potato beetle has the genetic resources to sidestep our attacks
The Colorado potato beetle’s rapid spread, hardiness, and recognizable tiger-like stripes have caught global attention since it began infesting potatoes in the 1800s. Credit: Zach Cohen

The Colorado potato beetle has evolved resistance to more than 50 different kinds of insecticides, making the insect a “super pest” that wreaks havoc on potatoes around the world.

New research finds that the beetle achieved this feat largely by turning to a deep pool of diversity within its genome, which allowed different populations across the U.S. to quickly evolve resistance to nearly anything humans have thrown at it.

The pest’s wealth of diversity and arsenal of existing resistance genes will likely make it hard to control in the future, regardless of what new insecticides researchers develop. But the new understanding of the pest’s genomic resources could help scientists design management systems that keep it in check.

“This beetle was one of the first to be attacked with chemicals in the modern era, and it’s been very successful at evolving past those attacks,” says Sean Schoville, a University of Wisconsin–Madison professor of entomology who led the new analysis. “For other insects we’re hoping to control, there’s lessons to be learned from studying this pest. What mechanisms does this insect use to get past these insecticides?”

Along with his collaborators at UW–Madison and other institutions, Schoville published his findings Jan. 19 in the journal Molecular Biology and Evolution.

Schoville’s team first sequenced the Colorado potato beetle’s genome in 2018. Since then, they’ve probed the genome to understand how the insect can overcome new insecticides as quickly as it does. To do so, they sequenced several dozen beetles from across the U.S. These regional populations vary in what pesticides they are resistant to and where they came from, which can give clues to the evolutionary history of the pest.

The scientists discovered that these different regional groups evolved so quickly because their parent populations already had the genetic resources necessary to overcome insecticides.

“The genes that evolve are well known to be involved in insect resistance. But what’s interesting is that different populations are altering different parts of genes or different genes in the same pathway,” says Schoville. This similar, but not identical, pathway to resistance across different populations is known as repeated evolution.

This rapid evolution based on a wealth of existing genetic diversity is at odds with an older model of evolution that assumed rare mutations have to slowly arise in a population. While new mutations do develop and can contribute to insecticide resistance, the potato beetle’s rapid response to new chemicals in different parts of the country can be explained only by its existing diversity.

The findings are unwelcome news for farmers and scientists hoping to turn the tide on the potato beetle’s attacks. It seems unlikely, Schoville says, that even a brand-new insecticide would keep the pest in check for long.

But armed with the knowledge of how the Colorado potato beetle has sidestepped our attacks, future research might help produce creative strategies to keep pace with this nemesis.

“More sophisticated models might help us learn how different management techniques affect the beetle’s evolution. That might allow us to change our management style to slow it down,” says Schoville.

Explore further

Colorado potato beetle genome gives insight into major agricultural pest

More information: Benjamin Pélissié et al, Genome Resequencing Reveals Rapid, Repeated Evolution in the Colorado Potato Beetle, Molecular Biology and Evolution (2022). DOI: 10.1093/molbev/msac016

Journal information: Molecular Biology and Evolution 

Provided by University of Wisconsin–Madison

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GMO crops have reduced pesticide poisoning among farmers, report finds

Joseph Maina | Cornell Alliance for Science | December 6, 2021

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Credit: Agroportal
Credit: Agroportal

This article or excerpt is included in the GLP’s daily curated selection of ideologically diverse news, opinion and analysis of biotechnology innovation. It is posted under Fair Use guidelines.Many countries have enjoyed improved economies and healthier populations by farming genetically modified (GM) crops, according to a report from the United Kingdom.

A primary benefit has been a reduction in pesticide poisoning among farm workers, particularly smallholder farmers, due to the low pesticide use associated with GM crops, observes the Report on Genetic Technologies by the UK’s Regulatory Horizons Council.

In India, for instance, the report cites a 50-to-70 percent reduction in pesticide applications on insect-resistant GM (Bt) cotton, which has led to significant health benefits.

“It has been estimated that this GM crop helps to avoid several million cases of pesticide poisoning per year,” the report states. “There have also been significant economic and health benefits for small farmers growing cotton in South Africa.”

Pesticide poisoning is a persistent challenge dogging agricultural production in many parts of Africa. Despite glaring evidence of potential harm to human beings and the environment, commercial and political interests often encumber mitigation efforts. Shocking reports of pesticide poisoning keep emerging from the continent.

As noted in one study on smallholder pesticide use in sub-Saharan Africa, pesticides are a common cause of acute poisoning in the region, with many cases going unreported. GM farming has been touted as a safe way of practicing agriculture because many GM crops serve to reduce pesticide use.

The adoption of Bt cotton, for instance, can substantially reduce the risk and incidence of pesticide poisonings, as shown by a pioneering study conducted in China. Using data from a survey of farmers in northern China, the report provided evidence of a direct link between the adoption of a GM crop and improvements in human health. Similar results have been documented for Bt maize.

The adoption of Bt cotton in Burkina Faso significantly lowered pesticide use in that crop. Farmers went from spraying their conventional cotton fields 15 times per season to control bollworm to spraying only twice with Bt cotton, which saw the crop’s popularity soar. By 2014, more than 70 percent of all cultivated cotton in Burkina Faso was GM. However, the government halted the crop in 2015, causing production to plummet and pesticide use to increase as farmers returned to growing conventional varieties.

The Regulatory Horizons Council report outlines two broad classifications of genetic technologies: First-generation genetic technologies, which are the basis of today’s widely used genetically modified (GM) crops; and the more recent second-generation technologies, which include genome editing, synthetic biology and engineering biology.

The report provides an edifying treatise on first-generation GM crops, showing their potential benefits for agriculture, the environment and society. It further scrutinizes the emerging opportunities, regulations and products associated with second-generation technologies.

GM crops were first introduced in the 1990s and have seen the fastest uptake by farmers over any other modern agricultural technology. Cultivation of GM crops expanded from 1.7 million hectares in 1996 to 179.7 in 2015 and now accounts for over 10 percent of the world’s arable land. Reported benefits include better economic outcomes for farmers, a reduction in pest-infestation in crops, increased insect biodiversity on farms resulting from adoption of insect-resistant crops, savings in the CO2 emissions that contribute to global warming, soil improvement and productivity gains resulting in potential land-saving outcomes.

The report also elucidates the emergent opportunities in agricultural biotechnology for post-Brexit UK, vouching for a rapid adoption of regulations that will be amenable to genetic technologies.Follow the latest news and policy debates on agricultural biotech and biomedicine? Subscribe to our newsletter.SIGN UP

Despite the proven potential of agricultural biotechnologies to meet societal needs that include provision of healthier diets, climate change mitigation and contributing to the United Nations Sustainable Development Goals, scientists, companies and policy makers in the UK and the EU concede that the European regulatory system for genetic technologies inhibits useful innovation, thus disadvantaging farmers.

“Since the UK is no longer a member of the EU, the Government has an opportunity to take a leading role in demonstrating how current regulatory systems can be adapted, or new regulatory systems developed, to enable innovative, safe and beneficial products of genetic technologies to reach their intended markets, at home and abroad,” states the report.

The EU adopted a process-based approach in regulating first-generation GM products, which lumped the process of genetic modification itself alongside all its products, regardless of their properties, within a common regulatory regime. This approach contrasts with the United States’ product-based approach, which focused on the product, its benefits and risks. The EU regulatory framework, along with the very precautionary and politicized approach to its implementation, has resulted in the absence of any significant adoption of GM crops in the EU and the departure of European companies working on GM technologies to the US and other countries.

Dr. Joseph Maina is a Senior Lecturer in the Department of Earth and Environmental Sciences at Macquarie University. Joseph’s ultimate goals are to understand and predict the impacts of environmental variability and change on social and ecological systems at local and global scales to support spatial planning & management.

A version of this article was originally posted at the Cornell Alliance for Science and is reposted here with permission. The Cornell Alliance for Science can be found on Twitter @ScienceAlly

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The Conversation

The fall armyworm invasion is fierce this year – and scientists are researching how to stop its destruction of lawns, football fields and crops

September 17, 2021 8.15am EDT


  1. Scott D. StewartProfessor of Entomology and Director of the West Tennessee AgResearch and Education Center, University of Tennessee

Disclosure statement

Scott D. Stewart’s research and extension programs at the University of Tennessee are partially supported by grants and contracts from Tennessee cotton, corn and soybean commodity boards, the USDA, and from various seed and pesticide companies for evaluation of their technologies.


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Across the Northeast, Midwest, South and Southwest United States, homeowners are watching with horror as their lawns turn from green to brown, sometimes in less than 48 hours, and wondering, “What happened this year – and how did it happen so fast?”

The culprit: the fall armyworm.

As an entomologist, I can attest that their appearance is nothing new: They’re an annual problem, but the scale of this year’s invasion is unprecedented. These voracious feeders are destroying lawns and grasses, attacking golf courses, pastures, football and soccer fields – and they can completely defoliate rice, soybean, alfalfa and other crop fields within days. They are called armyworms because of their habit of marching across the landscape.

The invader

The fall armyworm, Spodoptera frugiperda, isn’t a worm. It’s a striped caterpillar, the larvae of an ordinary and benign brown moth. It’s native to the Americas and is extremely adaptable, thriving everywhere from lush forests to arid regions and in pristine, disturbed and urban landscapes.

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The armyworms’ impact on lawn grass can be dramatic. Scott D. Stewart, Author provided

This moth survives year-round in warmer locales, from the tip of South America to the southern U.S. Each year they invade more northern regions until cold weather ends their occupation.

From larvae to moth, its entire life cycle is about 30 days during the summer and 60 in spring and fall. Adult moths survive just two weeks. During that time, a female lays up to 2,000 eggs, deposited underneath leaves in clusters of 100 to 200.

The moths aren’t the problem; it’s their larvae. When eggs first hatch, the tiny caterpillars are barely noticeable, about one-sixteenth of an inch long. By the time the caterpillars reach full size – an inch and a half – they’ve become ravenous eaters.During its short life cycle, the fall armyworm can devastate important crops.

Depending on the season, the armyworms eat and grow for 14 to 30 days. Initially, they chew holes in leaves, sometimes reducing them to a lacework skeleton. If they run out of food, they become cannibals, with the larger armyworms preying on the smaller ones.

Then they burrow into the ground, encase themselves in a cocoon and pupate. When they emerge as moths, the cycle repeats, with the next generation propelling their expansion across the country.

An invasive species

Meanwhile, fall armyworms have spread across the globe as an invasive species, reaching the Near East, Asia, Australia, Africa and India. Without its native complement of parasites, predators and diseases to control it, these rapacious caterpillars pose a serious agricultural threat to these newly invaded countries.

Farming practices have fueled their proliferation. Most of these countries do not grow armyworm-resistant GMO crops and many have limited access to newer insecticides and modern application equipment.

Armyworms have been particularly destructive in sub-Saharan Africa, where they devour maize, the continent’s staple crop. Damage is estimated at US$2 billion per year. It also causes major damage to corn, rice, sorghum, sugar cane, vegetable crops and cotton.

This year’s ‘perfect storm’

Entomologist David Kerns sounded the alarm in June, warning that armyworms in Texas were bad and heading north and east. They’d gotten off to an early start, aided by good weather in their winter home range.

Once the moths are on the move, they leave their natural enemies behind, taking their new territories by surprise. They can migrate hundreds of miles, riding the winds to reinfest the northern part of their domain. But with an early start this year, they rode the winds farther than normal. By the end of August, much of the southern U.S. east of the Rocky Mountains had suffered serious assault, akin to a plague of locusts.

An adult armyworm moth (genus Spodoptera) Scott D. Stewart, Author provided
Newly hatched armyworms. Scott D. Stewart, Author provided

How do we control the invasion?

There are two ways to deal with an infestation: Wait it out, or fight. For those concerned about lawns, waiting may be the answer. Armyworms don’t feast on all grasses, and a well-established lawn will often recover, though it may not look great for a while. However, armyworms particularly love freshly laid sod, which may sustain irreparable damage.

Waiting it out isn’t an option for farmers. Applying insecticides is the only way to save crops, which may prove difficult as pandemic-fueled disruptions have left some insecticides in short supply. Success is a numbers game: Killing 80% of a group of 100 armyworms controls them, but with larger numbers of armyworms, killing 80% still means many crops will be devastated.

Some evidence also suggests that fall armyworms may be developing more resistance to certain insecticides, and it wouldn’t be the first time. This pest is infamous for developing resistance to the insecticidal proteins from Bacillus thuringiensis produced by genetically modified crops. My colleague Juan Luis Jurat-Fuentes is trying to understand how the fall armyworm becomes resistant to Bt toxins in Bt corn and cotton.

His work is also revealing how insecticidal protein-resistant armyworms are spreading their genes across the Americas. We are currently collaborating on a project using gene silencing to help control outbreaks of fall armyworm. The technique can turn off specific genes, including those that make the fall armyworm resistant to insecticides. The goal is to develop extremely specific and effective insecticides that have minimal impact on the environment and other wildlife species.

Fall armyworm on damaged corn. ossyugioh/Getty Images

The cost – and the future

The economic costs of fall armyworm invasions are high. This year alone they have preyed upon millions of acres of crops, hayfields, lawns and turfgrass. Farmers, homeowners and businesses have spent tens of millions of dollars on insecticide applications. Some farms have suffered major crop losses.

The battle is not quite over. It will continue for a few more weeks as the fall armyworm continues to spread farther north and east.

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Was this “year of the armyworm” a fluke? Will they be back? The answer to both questions is probably yes. We don’t know why fall armyworms started off en masse in 2021, but the extreme infestations were hopefully a rare anomaly. There is concern, however, that a warming climate will allow these and other subtropical and tropical insects to expand their territories northward.

We do know that armyworms will reinvade much of the Southern U.S. every year as they always have, and northern states should expect more frequent incursions from insect neighbors to the south.

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Amplicon technology: a new way to detect tobacco whitefly resistance

Tobacco whitefly (Bemisia tabaci) is a harmful pest distributed globally and can have a serious impact on vegetable production. Its resistance to crop protection is one of the difficulties in practice. Therefore, the detection of the resistance gene mutations can provide an important reference for pest management. However, the individual Bemisia tabaci is small, with a body length of less than 1mm. The traditional single-head sequencing operation is difficult, and often a small amount of gDNA is obtained, but it consumes a lot of time and resources, and new detection methods are urgently needed in scientific research.

© Tomasz Klejdysz | Dreamstime.com 

The Vegetable Pest Research Laboratory has established a method to detect gene mutation frequencies in micro-insects using amplicon technology and detected the frequency of two pyrethroid resistance-related point mutations of sodium ion channel genes in the Bemisia tabaci population. The method is efficient and reliable and solves the problem of detecting gene mutation frequency of micro-insects.

Amplicon sequencing was originally used to detect the community composition of soil, plant, or animal gut microbes, which can be used to analyze the interaction between microbes and animals and plants. The amplicon sequencing method is based on the Next-generation Sequencing technology, which has high sequencing efficiency and can perform centralized detection of a large number of samples.

The team established an efficient approach for detecting the frequency of mutation by amplicon sequencing. The frequencies of L925I and T929V in VGSC associated with pyrethroid resistance were detected in this study, which could provide foundational data for resistance management of B. tabaci.

This research provides an efficient and reliable method for detecting the frequency of gene mutations in micro-insects and is helpful to the development of pest control in the field. The research was published in the entomology professional journal Pest Management Science (impact factor 3.75), Q1 of the Chinese Academy of Sciences. The first author of the thesis is Wei Yiyun, a postdoctoral researcher at the Lab. Associate researcher Wang Ran, Dr. Qu Cheng, and Dr. Guan Fang from Nanjing Agricultural University participated in part of the work. Researcher Luo Chen is the corresponding author of the paper.

Source: https://doi.org/10.1002/ps.6327

Wei, Y., Guan, F., Wang, R., Qu, C. and Luo, C. (2021), Amplicon sequencing detects mutations associated with pyrethroid resistance in Bemisia tabaci (Hemiptera: Aleyrodidae). Pest Manag Sci, 77: 2914-2923. https://doi.org/10.1002/ps.6327 

Publication date: Thu 30 Sep 2021

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