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Climate, genetics can affect how long virus-carrying mosquitoes live

Topic(s): Entomology and Nematology, Pests, RECs, Research

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GAINESVILLE, Fla. — It’s just math: The longer a mosquito lives, the better its odds of transmitting disease to humans or animals.

But as it turns out, factors such as the mosquito’s own genetics and the climate it lives in have a big – albeit complicated and not wholly understood – role to play in its lifespan.

University of Florida researchers, hoping to better understand how West Nile virus affects mosquitoes, set up an experiment they outline in the Journal of Vector Ecology’s current issue.

Mosquitoes can transmit any number of pathogens to humans, including protozoan malaria, West Nile, dengue and chikungunya viruses. Malaria cases range between 350 million and 500 million each year, with 1 million to 3 million deaths every year.

In the experiment, UF researchers examined survival rates for mosquitoes from two laboratory-reared colonies, one from Gainesville and one from Vero Beach.

Half of each of the mosquito colonies was fed West Nile virus-infected blood, the other half kept as a control population, and fed blood without the virus.

They divided the groups once more, this time keeping the mosquitoes at two temperatures, one group at 80.6 degrees, the other at 87.8 degrees Fahrenheit – a rather large difference in temperature for cold-blooded insects.

Their findings were both unexpected and illuminating, said Barry Alto, a UF assistant professor of arbovirology based at the Florida Medical Entomology Laboratory in Vero Beach.

“Our results indicate that interactions between mosquitoes and arboviruses are really complex … these things that haven’t really been taken into account previously might make a difference,” said Alto, part of UF’s Institute of Food and Agricultural Sciences.

The researchers found that warmer temperature shortened survival.  Also, for the most part, the Vero Beach mosquitoes lived longer than those from Gainesville, indicating that some groups, or strains, of mosquitoes might just be genetically hardier than others.

They found that in general, the mosquitoes fared better at cooler temperatures.

But they also found that the West Nile virus-carrying mosquitoes from Gainesville fared worse than their counterparts at the hotter temperatures, and to their surprise, that the Vero Beach-bred mosquitoes carrying West Nile virus lived longer than all other groups at the cooler temperature, including control-group mosquitoes not exposed to the virus.

Ingesting virus-infected blood may take a toll on the mosquito’s health, Alto said, but it’s clear that other factors: immune response, genetics and the environment, are also at play and need more study.

“It’s quite complex, there’s a lot of stuff going on here,” Alto said. “But I think the take-home  message is that these viruses, when they’re in mosquitoes, not only can they alter parameters like survivorship that are really important to disease transmission, but they can alter them in non-intuitive ways — sometimes enhancing, sometimes decreasing survivorship, and that those situations arise when you start considering other factors of the environment, like temperature.”

Adding to scientists’ knowledge base of how disease affects insects is key to finding the best ways to limit its spread, Alto said.

“In the most general sense, in order for humans to control disease, we really need to know how the mosquito interacts with these viruses,” he said. “In the absence of a human vaccine, the best way to control any sort of mosquito-borne virus is to control the mosquito. Simply put, if the mosquito doesn’t bite you, you’re not going to get the pathogen.”

Besides Alto, the research team included Stephanie Richards, an assistant professor at East Carolina University; Sheri Anderson, a former graduate student at the Florida Medical Entomology Lab and Cynthia Lord, an associate professor in modeling of vector-borne disease transmission, also of the FMEL. The study was funded by the National Institutes of Health and UF/IFAS.

Contacts:

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Beloved crape myrtle in nurseries now susceptible to bacterial leaf spot, researchers say

Topic(s): Landscaping, Pests, RECs, Research, Uncategorized

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GAINESVILLE, Fla. — It’s enough to send gardeners into conniptions.

Crape myrtle, a tree adored for its bright flowers that scream summer, care-free maintenance and even its colorful bark, now has a disease problem – although so far, only in the commercial nursery setting.

University of Florida researchers had been getting sporadic reports from nursery owners over the last five years of a leaf spot problem, and those reports have only increased in frequency. Through genetic testing, scientists identified the disorder as being caused by the bacterium Xanthomonas axonopodis. The disease is most likely spread by wind-driven rain or overhead irrigation, and some crape myrtle varieties are more susceptible than others.

“I’ve been working with crape myrtles for a long time, and they’ve been such a disease-resistant plant for such a long time, so it’s pretty significant when their susceptibility to disease is increased,” said Gary Knox, an environmental horticulture professor with UF’s Institute of Food and Agricultural Sciences.

The U.S. crape myrtle crop had a value of nearly $43 million in 2010, and Florida is its second-biggest producer, behind Texas. Florida has more companies producing crape myrtle, however, with 130 compared with 72 in Texas.

In the June issue of the journal Plant Disease, the UF/IFAS team outlined the first report of the disease and the work they did to identify it. They believe it is the first report of the bacterium causing leaf spot in crape myrtle.

Bacterial leaf spot doesn’t kill the ornamental tree, but creates spots on its leaves that eventually turn yellow and drop.

The researchers say, for now, the disease affects only crape myrtle commercial producers and is spread by factors such as overhead irrigation systems and large numbers of plants kept in close quarters.

The bad news is that the bacterium is widespread.

“I think you can safely say that nearly every crape myrtle producer would have the disease at this point,” Knox said.

While the disease appears contained in the commercial sector, that could change.

“Most bacterial diseases can be spread in wind-driven rain, and in Florida, we know there’s no shortage of that,” said Mathews Paret, an assistant professor of plant pathology who led the study.

Paret and Knox are based at the North Florida Research and Education Center in Quincy.

Scientists suggest an integrated management approach to the problem, rather than a silver bullet that only stops the problem temporarily.

Choosing resistant varieties, moving from overhead irrigation to drip irrigation and the limited use of bactericides would be part of such an integrated strategy, the researchers said.

The varieties Natchez, Osage, Fantasy, Basham’s Party Pink and Miami have proven highly resistant to bacterial leaf spot while Carolina Beauty, Arapaho, Tuscarora, White Chocolate, Red Rocket and Rhapsody in Pink were more susceptible in field trials funded by the Florida Nursery Growers and Landscape Association.

Steve Bender, a senior writer at Southern Living magazine, “The Grumpy Gardener” blogger and well-known gardening author, says it would be a huge disappointment if the disease ever makes the leap from nurseries to home gardens.

Crape myrtle is so close to Southern gardeners’ hearts that they endlessly debate such topics as how to spell its name (variants include crepe myrtle, crape myrtle and even crapemyrtle),  and the annual rite Bender calls  “crape murder” – an unceremonious lopping of its limbs.

It’s an iconic tree, he said, mostly because it’s little work for a big payoff.

“It’s ideally suited to the southern climate, it blooms for a long time, it comes in lots of different colors and you even get nice color in the fall,” Bender said. “It’s kind of hard to kill, and pretty much any idiot can grow one. And up until now, it’s had very few problems.”

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Citrus industry set to welcome state-of-the-art greenhouse at Mid-Florida REC in Apopka

Topic(s): Agriculture, Announcements, Citrus, IFAS, RECs

 

The UF/IFAS Mid-Florida REC in Apopka is home to a new $200,000 citrus nursery greenhouse.

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GAINESVILLE, Fla. – The citrus industry has just gotten its own state-of-the-art greenhouse, dedicated solely to citrus nursery research as the state continues its fight against citrus greening – and industry and research officials are set to celebrate the gift March 25.

The $200,000 facility is located at the University of Florida’s Mid-Florida Research and Education Center in Apopka.  Officials say it was built there to shield the young plants from greening in the state’s main citrus-crowing areas of Central and South Florida, as federal guidelines suggest. (more …)

New study finds Burmese pythons have homing sense

Topic(s): Invasive Species, RECs, Research

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GAINESVILLE, Fla. — If you pick them up and drop them in a new location, most snakes will move rapidly but erratically, often traversing the same terrain before giving up and settling into their new digs.

Burmese pythons aren’t most snakes.

A team of researchers including scientists from the University of Florida’s Institute of Food and Agricultural Sciences has discovered that the giant snakes – which have invaded and affected the food chain in Everglades National Park and Big Cypress National Preserve – can find their way home even when moved more than 20 miles away.

The findings, to be published March 19 by the Royal Society’s Biology Letters, change how researchers understand pythons’ behaviors and intellect.

“This is way more sophisticated behavior than we’ve been attributing to them,” said Frank Mazzotti, a UF/IFAS wildlife ecology and conservation professor based at the Fort Lauderdale Research and Education Center. “It’s one of those things where nature makes us go ‘wow.’ That is truly the significance of this.”

In 2006 and 2007, researchers captured 12 pythons and surgically implanted radio transmitters that allowed them to track the snakes’ movements. As a control group, they returned six of the snakes to the spot of their capture and turned them loose.

The remaining six snakes were taken to spots ranging from 13 to 22 miles away from where they had been captured and turned loose. To the researchers’ surprise, the snakes oriented themselves toward “home” and maintained their bearings as they traveled.

And although it took between 94 and 296 days for five of the six snakes to get within three miles of home, partly due to it being the snakes’ dormant season, the reptiles kept that orientation – a clear signal to scientists that the snakes have both “map” and “compass” senses.

The relocated snakes appeared to use local cues at the release site to understand their position relative to home (the map sense), and appeared to use cues along the way (their compass sense) to ensure that they remained on track, although the researchers don’t yet know what those cues are: smell, perhaps the stars, light or some kind of magnetic force.

Mazzotti said it’s helpful for researchers to know that the snakes move purposefully through their environment, but in reality, it’s not that much help.

“It amps up a little bit our concern about the snakes, but given all the other things we know about pythons, the amount of increasing concern is minor,” he said.

The Burmese python has been an invasive species in South Florida since about 2000 likely stemming from accidental or purposeful releases by former pet owners. The largest python found in the Everglades area had grown to more than 18 feet.

The snakes suffocate and eat even large animals, such as deer and alligators, and in 2012, a research team that included Mazzotti found severe declines in sightings in python-heavy areas of native animals including raccoons, opossum, bobcats and rabbits.

In 2012, the federal government banned the import and interstate trade of four exotic snake species: the Burmese python, the yellow anaconda, and North and South African python.

Besides Mazzotti, the team of authors behind the Biology Letters paper include lead author Shannon Pittman, a doctoral candidate at University of Missouri-Columbia; Kristen Hart, a United States Geological Survey researcher, Michael Cherkiss, a USGS senior wildlife biologist; Skip Snow, a United States National Park Service biologist, Ikuko Fujisaki, a quantitative ecologist with the Fort Lauderdale REC, Brian Smith, a USGS biologist and Michael Dorcas, a Davidson College biology professor.

A link to frequently asked questions:

http://www.usgs.gov/faq/categories/10721/4751

Contacts

Writer: Mickie Anderson, 352-273-3566, mickiea@ufl.edu

Source: Frank Mazzotti, 954-577-6338, fjma@ufl.edu

Photo caption: A snake handler displays a Burmese python for onlookers at the 2013 Python Challenge event at the Ft. Lauderdale Research and Education Center in Davie, Florida. UF/IFAS Photo by Tyler Jones.

UF/IFAS names Calvin Arnold to lead Southwest Florida Research and Education Center

Topic(s): Announcements, RECs

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GAINESVILLE, Fla. — Calvin Arnold, who led the Southwest Florida Research and Education Center for 10 years, will return to that post next month, UF’s Jack Payne, senior vice president for agriculture and natural resources, announced Tuesday.

“We are so fortunate to have Dr. Arnold back with UF/IFAS,” Payne said. “He is well- versed in the issues that are most critical for agricultural producers in that region, which is a huge advantage, and he’s a great leader, as well.”

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UF researchers find genetic cause for citrus canker, putting them a step closer to a cure

Topic(s): Agriculture, Citrus, IFAS, RECs

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GAINESVILLE, Fla. — Researchers from the Institute of Food and Agricultural Sciences at the University of Florida are closer to finding a possible cure for citrus canker after identifying a gene that makes citrus trees susceptible to the bacterial pathogen.

Citrus canker, which causes pustules on fruit, leaves and twigs, is a highly contagious plant disease and spreads rapidly over short distances. Wind-driven rain, overhead irrigation, flooding and human movement can spread citrus canker. Human transport of infected plants or fruit spreads the canker pathogen over longer distances. (more …)

Nuessly named interim director of UF’s Everglades Research and Education Center

Topic(s): Agriculture, Announcements, Honors and Appointments, IFAS, RECs

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GAINESVILLE, Fla. – Gregg Nuessly, a professor of entomology and nematology at the University of Florida’s Everglades Research and Education Center in Belle Glade, has been named interim director of the center.

Nuessly has worked at the Everglades research center since 1989 and has served as associate center director for the past two years. The center is part of UF’s Institute of Food and Agricultural Sciences.

“As interim center director, I will work to broaden statewide cooperative efforts for research and extension while continuing the mission of the EREC and UF,” Nuessly said. “The strength of the EREC lies with the diverse faculty and staff collaborating in interdisciplinary research and extension to solve local and regional agricultural and wildlife issues. Our strong relationships with local growers and groups are also key to past and future successes for the EREC.”

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Auburn soil science professor named center director at West Florida REC

Topic(s): Announcements, RECs

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GAINESVILLE, Fla. – The University of Florida Institute of Food and Agricultural Sciences this week named Wes Wood, an expert in nutrient management, to head its West Florida Research and Education Center in Jay and Milton, Fla.

Wood is currently a professor of soil science at Auburn University, where he is also the coordinator for the university-wide environmental science undergraduate major. In addition to teaching classes in nutrient management, soils and environmental quality, Wood conducts research on carbon and nutrient cycling in managed and natural ecosystems.

(more …)

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