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Posts Tagged ‘Asian citrus psyllid’

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http://www.eurekalert.org/pub_releases/2014-10/uoc–omm102314.php

Odor molecules monitor pest that spreads devastating citrus disease

UC Riverside scientists develop blend of odor molecules that are effective in monitoring spread of Asian citrus psyllid and huanglongbing
Asian citrus psyllid81417_rel

 

IMAGE: The Asian citrus psyllid, seen here, is an efficient vector of a bacterium that causes a lethal citrus disease.

 

RIVERSIDE, Calif. – The Asian citrus psyllid (ACP) is an efficient vector of a bacterium that causes a lethal citrus disease, huanglongbing (HLB), one of the most destructive diseases of citrus worldwide.

ACP-HLB is a serious threat to California’s annual $2 billion citrus industry. This insect-disease combination has cost Florida’s citrus industry $1.3 billion in losses, and production costs have increased by 40 percent.

Now a research team at the University of California, Riverside has targeted the olfactory system of the psyllid, and identified a suite of odorants – odor molecules – that the ACP olfactory system detects. Some of these odorants can modify the behavior of ACP and lead to the development of tools to tackle its spread worldwide, the researchers report.

“The ACP olfactory system is sensitive to a variety of odorants released by citrus plants. This presents an opportunity to develop attractants and repellents using odors,” said Anandasankar Ray, an associate professor of entomology and the director of the Center for Disease Vector Research, who led the research project.

Ray explained that the ACP detects citrus plant odors using tiny pit-like sensors (containing neurons) on its antenna. His lab performed a large-scale analysis of numerous citrus emitted odors and identified those odors that strongly activate the citrus odor sensitive neurons on the ACP antenna. Then, using a blend of activating odorants, the researchers developed an efficient attractant that could lure ACP to yellow sticky traps.

“We anticipate that this odor-based insect lure could be of use to growers in California and other parts of the world where ACP invasion is occurring,” Ray said.

Study results on the lures appear in the Oct. 27 issue of PLOS ONE. The large scale identification of odors that are detected by ACP appears in the 39th issue of Chemical Senses. Both studies were funded by the California Citrus Research Board.

One of the major gaps in ACP control is the lack of effective surveillance traps to track the rapid spread of these highly invasive insects that are fast spreading globally. Currently, HLB is mostly managed by spraying insecticides and swiftly removing infected trees. But if the ACP develops insecticide resistance, commercially managed citrus groves could be in jeopardy. Further, abandoned citrus groves could become prolific reservoirs of HLB.

The blend of odors Ray and his team of researchers identified consisted of myrcene, ethyl butyrate and p-cymene – odors found in nature. To test whether this blend was indeed effective as an attractant, Ray and his team of researchers performed field trials, spread over 10weeks, in citrus trees located in backyards in a residential neighborhood in El Monte, Calif. They found that the odor-based yellow traps caught nearly 230 percent more ACP than conventional yellow traps placed on the same trees.

“What’s particularly encouraging is that these three chemicals are affordable, useful in small quantities and safe for human handling,” Ray said. “They could be developed into monitoring and surveillance tools. Similar approaches can be taken to develop control strategies using odors for other insect pests of crops as well. Our study also reports identification of odors that block the ACP olfactory system from detecting citrus odors and have potential for development into repellents.”

The Ray Lab has already identified odor molecules that can severely impair, if not completely disrupt, the carbon dioxide and skin-odor detection machinery of mosquitoes. Recently his lab discovered the receptor proteins in insects that detect the repellent DEET and used it to identify several naturally occurring, pleasant smelling odor repellents for mosquitoes and flies that were better than DEET. Both are approaches that can help control the spread of diseases mosquitoes transmit – malaria, dengue, yellow fever, filariasis and West Nile virus.

Besides California, ACP and HLB are found in Florida, Louisiana, Georgia, South Carolina, the Caribbean, Central America, and large parts of Mexico and Brazil.

When the ACP feeds on leaves and stems, it injects the bacterium into the trees and, within a few years of infection, the leaves turn yellow and the fruit becomes misshapen and bitter. The tree dies within 5-8 years of infection.

Ray was joined in the PLOS ONE study by UC Riverside’s Iliano V. Coutinho-Abreu, Lisa Forster and Tom Guda; and by Coutinho-Abreu, Forster, Shane McInally and Robert Luck in the Chemical Senses study.

The California Department of Food and Agriculture assigned the location for the field trials after securing permission from landowners for setting up traps. Toxicity information and exposure potential of the chemicals tested as lures were reviewed by the Office of Environmental Health Hazard Assessment, California Environmental Protection Agency.

The UCR Office of Technology Commercialization has filed a patent on the technology reported in the research paper, which has been licensed to ISCA Technologies.

Contact: Iqbal Pittalwala
iqbal@ucr.edu
951-827-6050
University of California – Riverside
@UCRiverside

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http://www.newswise.com/articles/uf-ifas-researchers-find-chemicals-that-treat-citrus-greening-in-the-lab

Released: 6/4/2014 9:35 AM EDT
Source Newsroom: University of Florida
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PLOS Pathogens
Newswise — GAINESVILLE, Fla. — A University of Florida research team is cautiously optimistic after finding a possible treatment in the lab for citrus greening, a disease devastating Florida’s $9 billion citrus industry. It is the first step in a years-long process to bring a treatment to market.
Claudio Gonzalez and Graciela Lorca led the research team that examined three biochemical treatments: phloretin, hexestrol and benzbromarone.
The team sprayed greenhouse tree shoots separately with one of the three biochemicals and were successful in stopping the bacteria’s spread, particularly with benzbromarone, which halted the bacteria in 80 percent of the infected trees’ shoots. They expect to begin field experiments with this treatment later this year. Their research was published in late April by the online open access journal PLOS Pathogens.
Gonzalez and Lorca are UF associate professors in the microbiology and cell science department, part of UF’s Institute of Food and Agricultural Sciences. The team also works under the auspices of the UF Genetics Institute.
The researchers found that benzbromarone targets a specific protein, known as LdtR, in the citrus greening bacterium. When benzbromarone binds to LdtR, it inactivates the protein, which disrupts a cell wall remodeling process critical for the greening bacterium’s survival inside a citrus tree.
“As a consequence of the chemical treatment, several genes were not expressed and the bacteria were not able to survive inside the phloem of the plant where osmotic pressure from sugar is high,” said Fernando Pagliai, a co-author of the study and a UF graduate assistant. Phloem is the living tissue that carries organic nutrients to all parts of the plant.
Benzbromarone is typically used to treat gout in humans.
Citrus greening first enters the tree via a tiny bug, the Asian citrus psyllid, which sucks on leaf sap and leaves behind bacteria. The bacteria then move through the tree via the phloem. The disease starves the tree of nutrients, damages its roots and the tree produces fruits that are green and misshapen, unsuitable for sale as fresh fruit or for juice. Most infected trees die within a few years.
The disease has already affected millions of citrus trees in North America and could wipe out the industry in the next decade if a viable treatment is not found.
UF/IFAS researchers have attempted everything from trying to eradicate the psyllid to breeding citrus rootstock that shows better greening resistance. Current methods to control the spread of citrus greening include removing and destroying infected trees.
Florida growers say they desperate for a treatment that will work.
“Every grower I know is just hanging by their fingernails, hoping and praying for a new discovery for treatment,” said Ellis Hunt Jr. of Lake Wales, whose family has been in the citrus business since 1922.
Industry experts, though, say it could be five to seven years before a new active-ingredient product could be commercially available because of the amount of time field testing takes and government regulations.
Jackie Burns, director of the UF/IFAS Citrus Research and Education Center in Lake Alfred, said because of those regulations, which are meant to ensure a safe food supply, researchers can’t accelerate testing and approval. And she noted that although the initial results of the research are promising, there is no guarantee the compounds will work under field conditions.
Other co-authors on the paper: Christopher Gardner, a research technician in microbiology and cell science; Max Teplitski, an associate professor in soil and water science; Svetlana Folimonova, an assistant professor in plant pathology; Lora Bojilova, a research technician; Anastasia Potts, a graduate assistant; and Amanda Sarnegrim and Cheila Tamayo, undergraduate students.

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