Feeds:
Posts
Comments

Archive for the ‘Research’ Category

SE farm press

citrus-greening-university-florida-asd
This approach to controlling citrus greening, by blocking bacterial transmission by the psyllid, runs contrary to existing ‘kill the insect’ strategies.

Logan Hawkes | Mar 04, 2017

Since the introduction of Huánglóngbìng (HLB–yellow dragon disease–or better known as citrus greening disease) reared its ugly head on U.S. soil in a Florida citrus grove in 2005, the disease has been a major threat to commercial citrus production across the country.

Before arriving in North America, HLB had already carved a path of destruction across the Far East, Africa, the Indian subcontinent and the Arabian Peninsula, and was discovered in July 2004 in Brazil. In its wake it left citrus growers around the world astounded at the inevitable and long-lasting risks the disease poses to global citrus industry.

During the first couple of years after reaching Florida, the disease had destroyed a huge section of the state’s successful citrus industry, and by 2009, just five years after its introduction in the region, almost every county within Florida had confirmed HLB cases among both commercial and private citrus groves. From there the disease spread

to adjoining states, eventually reaching citrus growing areas in Texas and finally as far west as California.The fight against HLB and the tiny psyllids that carry the bacteria from tree to tree is about as old as the disease itself. Recognizing the disease had the ability to threaten the global citrus industry, researchers from around the world began working on possible solutions to combat the spread of this dangerous citrus killer.

In spite of early efforts however, the tell-tale signs of the disease kept spreading.

 The early symptoms of HLB include leaves with yellowing veins appear along with asymmetrical chlorosis referred to as “blotchy mottle.” These are the most diagnostic symptoms of the disease, especially on sweet orange. Growers, ever fearful the disease would reach their trees, have been on constant lookout for leaves that are slow to develop and often with a variety of chlorotic patterns that often resemble mineral deficiencies such as those of zinc, iron, and manganese.

Regardless of treatment efforts, once established in a grove, the end result of the disease is proving to be inevitable, the complete decay and destruction of all infected trees.

Detection of the disease is one of the first hurdles facing citrus growers in modern times. When it comes to fighting HLB, growers face a number of unique challenges. For one, HLB-infected citrus trees do not show symptoms during the first year of infection, so there is a long period of time when a grower cannot visually detect an infected tree. But that hasn’t stemmed research efforts.

The spreading pandemic of the disease served to rally the global citrus industry and the many researchers who support it. Soon new and innovative treatments were being tested. In addition to antibacterial management and control and management of the psyllids that carry the disease, tree removal became a standard procedure to help curtail the rapid spread of the bacterium.

Soon, beneficial parasitoids were introduced and widely used to help control psyllid populations. Heat treatments in nurseries and on field trees covered by plastic wrap offered some slowing of the disease process in early research efforts. Hundreds of millions of dollars were being spent worldwide searching for a cure to the disease. A zinc-based bactericidal spray seemed to offer some hope.

Before long, breeders were offering new citrus varieties that were proving resistant to the bacterium that causes HLB. Bio-engineers have been devising methods to make citrus trees less attractive to the psyllids that carry the disease. But in recent months a new idea has surfaced, and while no one is ringing the bell of victory, researchers on the project are quietly voicing new hope in the war against the disease.

HOW IT WORKS

According to researchers, the reproductive and feeding habits of the psyllid make it the perfect carrier of the bacterium. An infected psyllid creates a localized infection when it feeds and transmits the bacterium into a citrus tree. It does not take long for the bacterium to spread throughout the plant, but the inoculum is first concentrated in the leaves and stems where the infected psyllid feeds. Female psyllids lay eggs in the same region where they feed. If these females are infected, their nymphs, which begin feeding in the infected area of the tree when they hatch, eventually acquire the bacterium, molt to the winged adult stage and disperse taking it along with them.

So researchers at the Boyce Thompson Institute, a premier life sciences research institution located in Ithaca, New York on the Cornell University campus, have concentrated their recent efforts on the psyllid itself as a possible link to the control of the disease.

Michelle Cilia, a Research Molecular Biologist at the USDA Agricultural Research Service and Assistant Professor at the Boyce Thompson Institute (BTI), and her team of researchers have been looking at a protein that makes the bellies of citrus psyllids blue and the possible connection it may have with the natural process of spreading the devastating bacterium in the first place. Researchers say Asian citrus psyllids with blue abdomens have high levels of an oxygen-transporting protein called hemocyanin.

According to Cilia, the hemocyanin protein is commonly found in the blood of crustaceans and mollusks. When harboring the bacterium Candidatus Liberibacter asiaticus ( or CLas) the disease is spread by the Asian citrus psyllid. This bacterium force the psyllids to ramp up their production of this protein. Cilia lab scientists, along with colleagues at the University of Washington and the USDA ARS at Fort Pierce, Fla., identified important protein interactions that must occur to perpetuate the transmission of bacterium to new trees.

They examined interactions occurring between the psyllid and the bacterium, and between the psyllid and its beneficial microbial partners. They also compared protein expression levels in both nymphs and adults. Their research shows that adult psyllids appear to mount a better immune response to CLas as compared to nymphs, which may explain why psyllids must acquire CLas during the nymphal stage to efficiently transmit CLas once they become adults.

“For many decades, scientists lacked the ability to look inside insects that transmit plant pathogens and understand what is going on,” said Cilia. “This is no longer true today, thanks to the painstaking work of our collaborators in the Bruce and MacCoss labs at the University of Washington. The new molecular tools developed by our University of Washington colleagues enable us to dissect the vector-pathogen relationship piece by piece to determine which components are important for transmission.”

The group showed that hemocyanin interacts with a CLas protein involved in a vital microbial metabolic pathway called the acetyl-CoA pathway. Scientists have previously targeted this set of biochemical reactions in bacteria when developing antibiotics.

John Ramsey, a USDA ARS postdoctoral associate in the Cilia lab and first author of the study, suspects that the increase in hemocyanin, and the blue color it imparts to the abdomen, could be evidence of an immune response to CLas infection. The findings raise the possibility that this response could be harnessed to help control the bacterium’s spread.

“The study is allowing you to look at your population of insects and say something about the immune system of the insect based on its color,” said Ramsey. “There’s the possibility that this could be a useful part of grove surveillance.”

In future work, the Cilia group plans to test whether there are differences in each color morph’s ability to spread the CLas bacterium. Results from this study will help inform future strategies to control citrus greening disease. Depending on which proteins they decide to target, these new approaches could prevent the psyllid from transmitting CLas or trigger an immune response against the bacterium.

This approach to controlling citrus greening, by blocking bacterial transmission by the psyllid, runs contrary to existing ‘kill the insect’ strategies, said Ramsey. Such an approach may provide a longer lasting solution because the insect isn’t under pressure to evolve to survive the treatment, which commonly occurs with pesticide usage.

Read Full Post »

CABI Plantwise Blog

Myzus persicae (green peach aphid); an alate (winged) adult
Myzus persicae (green peach aphid); an alate (winged) adult

Recent research highlights why the green peach aphid (Myzus persicae) is one of the most successful crop pests. These findings will help further the development of effective management and control measures which will ultimately reduce worldwide crop losses.

The green peach aphid is one of the most challenging crop pests, living on hundreds of host plants in over 40 families. This makes it an impressive generalist compared to many other aphids, a large number of which are only adapted to survive on one species. Key crops impacted by this pest include sugar beet, beans, potato, tomato and oilseed rape.

So how can it be such a wide ranging generalist? Recent research, carried out by the Earlham Institute (EI) and John Innes Centre (JIC) in the UK, has found that its ability to survive on so many hosts is largely down to its genetic plasticity (Mathers et al., 2017). After just two days, scientists were able to see that genes responsible for helping aphids adjust to different plants rapidly increased or decreased in activity when an individual was moved to a different host.

Interestingly, it seems that many of the genes involved are not specific to this species of aphid, but that the green peach aphid is just particularly well adapted to adjusting to the expression of the key genes.

Not only can it adapt well to different hosts, the pest transmits over 100 plant virus diseases, including Beet western yellows virus, Bean leaf roll virus and Potato leaf roll virus. Losses caused by these plant diseases can be very high – sugarbeet losses due to beet yellows can be up to 50%. Furthermore, the green peach aphid has developed resistance to over 70 different pesticides, making it difficult to control.

Then there’s its ability to reproduce prolifically. Females can give birth to females without mating with a male (clonal reproduction). Consequently green peach aphids can have up to 30 generations a year (Texas A&M University, 2017).

All in all, it’s no wonder that the green peach aphid is such an incredibly successful pest, unfortunately causing major widespread damage every year. This latest research is a significant step towards understanding how the pest is so successful, paving the way for more effective management and control methods.

For more information, read How to be a successful pest: lessons from the green peach aphid by the Earlham Institute.

You can also find out information regarding the green peach aphid on our Plantwise Knowledge Bank.

CABI, 2017. Green peach aphid (Myzus persicae). In: Plantwise Knowledge Bank. Wallingford, UK: CAB International. http://www.plantwise.org/knowledgebank/datasheet.aspx?dsid=35642

Earlham Institute, 2017. How to be a successful pest: lessons from the green peach aphid. UK: Earlham Institute. http://www.earlham.ac.uk/how-be-successful-pest-lessons-green-peach-aphid

Mathers TC, Chen Y, Kaithakottil G et al., 2017. Rapid transcriptional plasticity of duplicated gene clusters enables a clonally reproducing aphid to colonise diverse plant species. Genome Biology, 18:27.

Texas A&M University, 2017. Green Peach Aphid. In: Texas A&M Agrilife Extension Series. Texas, USA: Texas A&M University. http://texasinsects.tamu.edu/aimg103.html


Visit the Plantwise website

Read Full Post »

 

ScienceDaily

Science News

Date:
January 12, 2017
Source:
University of California – San Diego
Summary:
Biologists have documented for the first time how very large viruses reprogram the cellular machinery of bacteria during infection to more closely resemble an animal or human cell — a process that allows these alien invaders to trick cells into producing hundreds of new viruses, which eventually explode from and kill the cells they infect.
FULL STORY

Cryo-electron tomography shows how the bacterial cell is reorganized to resemble a more complicated plant or animal cell with a red nucleus-like compartment and ribosomes, the smaller light blue structures. The reproducing viruses appear with dark blue heads and pink tails.
Credit: Image by Vorrapon Chaikeeratisak, Kanika Khanna, Axel Brilot, Katrina Nguyen

Biologists at UC San Diego have documented for the first time how very large viruses reprogram the cellular machinery of bacteria during infection to more closely resemble an animal or human cell — a process that allows these alien invaders to trick cells into producing hundreds of new viruses, which eventually explode from and kill the cells they infect.

In a paper published in the January 13 issue of Science, the researchers conducted a series of experiments that allowed them to view in detail what happens inside bacterial cells as the invading viruses replicate.

“Scientists have been studying viruses for a hundred years, but we’ve never seen anything like this before,” said Joe Pogliano, a professor of molecular biology who headed the research team. “Every experiment produced something new and exciting about this system.”

Viruses that infect bacteria, also known as bacteriophages, are some of the most numerous entities on earth.

“We chose to study a family of unusually large bacteriophage and to apply cutting edge methods to watch their replication in unprecedented detail,” said Kit Pogliano, a professor of molecular biology who participated in the study.

Joe Pogliano and his colleagues found that shortly after bacteriophages infect bacteria, they destroy much of the existing architecture of the bacterial cells, including bacterial DNA, then hijack the remaining cellular machinery. The viruses then reorganize the entire cell into an efficient, centralized factory to produce the next generation of viruses.

“This factory and the surrounding arrangement of the infected cell are remarkably similar to the organization seen in plant and animal cells,” said Pogliano.

Bacteria lack many of the specialized structures that compartmentalize cellular processes in plant or animal cells, which biologists call “eukaryotic” cells. Bacteria, for example, lack an enclosed nucleus, which contains genetic information and acts as the control center of the cell.

But Vorrapon Chaikeeratisak, a postdoctoral fellow, and Katrina Nguyen, a graduate student in Pogliano’s laboratory, found that invading viruses organize the structures within bacteria to mimic those found in eukaryotic cells.

Using fluorescent microscopy, the two biologists discovered that as viruses replicate within bacterial cells, they build compartments to separate the different processes going on during infection.

“These compartments enclose all the viral DNA, just as a nucleus does in a plant or mammalian cell,” said Chaikeeratisak, the first author of the paper. “DNA processes, like replication or transcription, occur inside the compartment while proteins are produced outside the compartment.”

Elizabeth Villa, a professor of chemistry and biochemistry at UC San Diego, and David Agard, a professor of biochemistry and biophysics at UC San Francisco, used a specialized technique, called “cryo-electron tomography,” to produce images of the processes that Chaikeeratisak and Nguyen initially discovered at extremely high magnification.

Those pictures showed viral offspring being assembled around the nucleus-like compartment in the bacterium. Eventually, these new viruses burst the cell open and spread out to infect neighboring cells.

“These observations of viral manipulation of a cell are completely unexpected, as no bacterial virus has been seen to reorganize a cell in so drastic a manner,” said Pogliano. “The restructuring of a simple cell to resemble an existing, more complicated system blurs the line between simple bacterial cells and those of ‘higher’ organisms, such as plants and animals.”

Could this be how multicellular organisms evolved? One existing theory, called “viral eukaryogenesis,” suggests that the first eukaryotic cell was created when a large virus took over a bacterium. Eventually, the bacterium and virus formed a compound cell, in which the virus evolved into the nucleus.

“It may be too early to know if this particular virus is an intermediate step in the transition from bacteria and viruses to multicellular eukaryotes, but this discovery could broaden knowledge about the origins of life as we know it,” said Pogliano.

The study was supported by grants from the National Institutes of Health (GM031627, GM104556, GM57045, 1DP2GM123494-01) and the Howard Hughes Medical Institute.


Story Source:

Materials provided by University of California – San Diego. Note: Content may be edited for style and length.


Journal Reference:

  1. Vorrapon Chaikeeratisak, Katrina Nguyen, Kanika Khanna, Axel F. Brilot, Marcella L. Erb, Joanna K. C. Coker, Anastasia Vavilina, Gerald L. Newton, Robert Buschauer, Kit Pogliano, Elizabeth Villa, David A. Agard, Joe Pogliano. Assembly of a nucleus-like structure during viral replication in bacteria. Science, 2017; 355 (6321): 194 DOI: 10.1126/science.aal2130

Read Full Post »

Delta Farm Press Daily

peanut-dryland-field-june-2015-burrower-bug

Unravelling the mysteries of the peanut burrower bug

Peanut farmers who don’t know the peanut burrower bug are fortunate. Growers who’ve battled the yield- and quality-reducing pest know something needs to be done to control it, and those growers can help find answers.

Brad Haire 1 | Jan 06, 2017

Peanut farmers who personally don’t know the peanut burrower bug are fortunate. Growers who’ve battled the yield- and quality-reducing pest know something needs to be done to control it, and those growers can help find answers.

A Georgia-based research project will hit the high-gears in 2017 to develop an index growers can use to gauge their risk for the pest and implement better ways to defend against it.

When Mark Abney arrived in Georgia in 2013 as the new peanut entomologist, there was plenty of interest (and pressure) to find ways to stop the ground-dwelling, peanut-pod-feeding bug, which for several years prior suddenly started causing major problems in parts of the state’s peanut-growing region, especially troublesome to dryland peanuts.

“There wasn’t a whole lot known about it then. There was some work done in South Carolina in the ‘90s and a little bit of work in Texas in the ‘70s,” Abney said. “We’ve learned some things in the past few years, but the reality is there still isn’t a whole lot known about it from a standpoint of its biology or why it became a pest for peanut.”

The peanut burrower bug is not an invasive species, which it is mistakenly believed to be. It is a native species to Georgia and confirmed to be as far north as Connecticut. So, it must have a wide range of host plants it can survive on — not just peanuts, he said.

“We think of it as the peanut burrower bug, and that is its common name but it eats other things or it couldn’t survive the northeast,” he said.

In 2013, Abney received money from the National Peanut Board and the Georgia Peanut Commission to do research projects with University of Georgia Extension county agents, putting light traps in 15 counties to find out when the bug was most active and distributed across the state. Another project looked at how tillage influences the pest and on-farm insecticide trials.

After a couple of years of collecting that preliminary data, Abney and a team used that data to get a USDA Crop Protection and Pest Management grant.

The CPPM project has several objectives, but the main two are:

  1. To find out how peanut burrower bugs communicate with their own special pheromone. Similar to how boll weevil traps work by using an artificially-made boll weevil pheromone to attract and trap what once was a devastating cotton pest, the burrower bug project will develop pheromone-based traps, which are much cheaper and more practical than light-based traps. To pinpoint the peanut burrower bug pheromone, Abney is collaborating with a Maryland-based USDA scientist who discovered the brown marmorated stink bug pheromone, which can now be synthesized to monitor for that invasive stink bug.
  2. To develop a risk index, or risk assessment tool, in which a grower can enter production information — such as crop history, soil type, insecticides, peanut variety, tillage system and location – and from that know how at risk a particular field might be for the burrower bug and if a level of treatment is economically needed and what precise treatment is recommended to lower that risk.

“We want to develop a way they can manage their risk before they even put a peanut in the ground,” he said.

There are not many management tactics for the peanut burrower bug available to growers. But the use of granular chlorpyrifos (Lorsban), irrigation and bottom plowing can reduce risk of burrower bug damage. But there is no one Silver Bullet.

One of the sneakiest problems with the peanut burrower bug is it feeds underground and unseen on the peanut pod, which lowers yield potential and in doing so also opens the door for aflatoxin to enter the pod. Every load of peanuts grown in the U.S. is graded. Even if a slight percentage of burrower bug damage (2.5 percent or greater of internal damage) is detected in a farmer’s load of peanuts, the grade of that peanut load drops to Seg. 2 and that farmer’s potential revenue for the load gets slashed.

A big mystery about the peanut burrower bug is why its presence and damage is so sporadic. It can be a big problem in one field and then a mile down the road at another field never be a problem. Very smart people, Abney said, from those at buying points to county agents, have tried to figure out this anomaly, but the investigations have mostly been confined to just one county or small region.

One of the biggest aspects of this new burrower bug project will be to find out on a state level exactly where, when and hopefully how the pest is a problem. Peanut growers who’ve dealt with the pest can help, Abney said.

“We’re working with Federal State Inspection Service to get information on all the burrower bug damage in the state. With that information we can go back, with the cooperation of buying point operators, county agents and especially the growers, potentially all of the growers who had burrower bug problem even if it was just 1-percent damage, and talk to that grower,” he said.

With that sort of statewide data set, you can better tweeze out commonalities, “and hopefully figure out why we see burrower bugs in this field and not in that field,” he said. “The scientist in me has to believe this is not random and that there has to be a pattern there and it is up to us to figure it out.”

Abney said he is working to get final permission to receive the names of peanut growers whose peanuts show burrower bug damage. He said the names of those growers will be protected and confidential to the project, and he hopes the growers will help.

Read Full Post »

veg-ipm-book-img_2871

The majority of the information in this book is drawn from technologies developed, tested, validated, and implemented by the Integrated Pest Management Innovation Lab (previously known as the  Integrated Pest Management Collaborative Research Support Program-IPM CRSP), supported by  USAID  Cooperative Agreements awarded to Virginia Tech.

Contents

Chap.1 – IPM for Food and Environmental Security in the Tropics

Chap. 2 – IPM Packages for Tropical Vegetable Crops

Chap. 3 – Virus Diseases of Tropical Vegetable Crops and Their Management

Chap. 4 – Exploring the Potential of Trichoderma for the Management of Seed and Soil-Borne Diseases of Crops

Chap. 5 – Physical, Mechanical and Cultural Control of Vegetable Insects

Chap. 6 – Integrated Pest Management of Cruciferous Vegetables

Chap. 7 – Integrated Pest Management of Okra in India

Chap. 8 – Integrated Pest Management of Onion in India

Chap. 9 – IPM Packages for Naranjilla: Sustainable Production in an Environmentally Fragile Region

Chap. 10 – IPM Technologies for Potato Producers in Highland Ecuador

Chap. 11 – Integrated Pest Management for Vegetable Crops in Bangladesh

Chap. 12 – Development and Dissemination of Vegetable IPM Practices in Nepal

Chap. 13 – IPM Vegetable Systems in Uganda

Chap. 14 – Impacts of IPM on Vegetable Production in the Tropics

 

ISBN 978-94-024-0922-2  ISBN 978-94-024-0924-6 (eBook)

Library of Congress Control Number: 2016957790

 

E.A. Heinrichs

IAPPS Secretary General

Asia Program Manager, IPM Innovation Lab

Read Full Post »

Western Farm Press

 

Unlike the Beach Boys musical group of old, Rodrigo Krugner is picking up bad vibrations.

It’s the sounds that glassy-winged sharpshooters make as they seek to find and mate with each other. That’s the focus of research by Krugner, research entomologist with the U.S. Department of Agriculture’s Agricultural Research Service in Parlier, Calif.

Krugner discussed “Mating disruption of the Glassy-Winged Sharpshooter: How does that sound?” at this year’s Grape Day event at California State University, Fresno (Fresno State). The insect can spread the deadly Pierce’s disease in grapevines faster than its smaller sharpshooter cousins, and Pierce’s costs California more than $100 million per year.

Krugner explained how the insects communicate with each other through seismic vibrational signals produced by their abdominal muscles. He is studying the degree at which “courtship signals” sent in call-response fashion can be disrupted.

Right now, the means for combatting the pest include insecticide applications in citrus orchards where they congregate, and releasing egg parasitoids.

Doppler vibrometer

Krugner explained that a laser Doppler vibrometer, a technology used in the aerospace industry to listen for vibrations, figured into his research. Both white noise and female calls reduced mating under laboratory conditions, but did not affect insect aggregation.

The efficacy of these and other signals in disrupting GWSS communication is being evaluated under field conditions in collaboration with Fresno State.

Electrodynamic shakers were attached to plant stems to generate disruptive and-or masking signals. The idea is to learn if the playback of selected GWSS signals onto grapevines will determine whether mating behavior is affected by disruptive signals and whether GWSS individuals can be either attracted or repelled by signals.

Krugner said males sometimes naturally mimic females to lure rivals away, and noted the process of mates locating each other often takes up to three hours.

Read Full Post »

Western Farm Press Daily
Maricopa, Ariz.

What is in this article?:

  • The largest agricultural robot on Earth working in an Arizona energy sorghum varietal trial.
  • The crop analytic robot is a Volkswagen-sized field scanner measuring crop growth with unprecedented resolution.
  • Plant data collected by the field scanner will be shared with crop breeders to speed up the breeding process in energy sorghum.

Pedro Andrade, left, University of Arizona, and Jeff White, USDA Agricultural Research Service, based in Maricopa, Ariz., stand in an energy sorghum variety trial where the world’s largest crop analytical robot records critical plant data.

 

Captain Kirk of Star Trek movie fame would feel right at home operating the controls of Planet Earth’s largest agricultural robot, currently operating in an energy sorghum varietal trial in Maricopa, Ariz.

The crop analytic robot, similar in appearance to a gantry crane, features a Volkswagen-sized field scanner loaded with the latest precision agriculture tools to precisely measure crop growth with unprecedented resolution.

The field scanner which moves east-to-west, north-to-south, and up-and-down above the field is located at the University of Arizona’s (UA) Maricopa Agricultural Center (MAC).

Over time, plant data collected by the field scanner will be shared with commercial and university crop breeders to help speed up the natural breeding process in energy sorghum varieties to boost yields and biomass content. The same tools could one day by use to collect plant data for breeding other types of crops.

Over the long term, improved energy sorghum varieties can help growers increase biofuel production, thus helping reduce this nation’s dependence on foreign oil.

Robot ribbon cutting

At a June ribbon-cutting ceremony for the robot field scanner system, DOE Advanced Research Projects Agency-Energy (ARPA-E) Director Joe Cornelius described the project as “agriculture’s version of the Hubble” (telescope), saying the project’s faster breeding results could place improved varieties in growers’ hands sooner.

The DOE’s Ellen Williams said the project would “revolutionize plant breeding.” She believes the sorghum project could accelerate the plant breeding process by two to three fold.

Shane Burgess, UA Dean of the College of Agriculture and Natural Resources, noted, “This is history in the making.”

Led by the Donald Danforth Plant Science Center in St. Louis, Mo., the field scanner robot project includes specialists from several universities, the federal government, and the private sector.

In the first year of the four-year project, the sorghum trial is largely funded by the U.S. Department of Energy (DOE). The project budget is about $8 million, not including the field scanner.

The UA receives about $1.6 million to cover the costs to construct the site and for its day-to-day operation.

 

Read Full Post »

Older Posts »