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West Nile Virus: A small list of mosquito predators for the Dallas area

This list is not comprehensive and will be updated as I find new information.  Nothing listed is 100% effective (as in, “kills every single mosquito”) and everything on the list does eat things other than mosquitoes (which might be a problem if your bats are eating all your dragonflies.)  This list is simply a “starting point” to consider.


Predators of adult (flying) mosquitoes:

Note: predators of adult mosquitoes are general insectivores, which means they will also go after the things that eat mosquitoes.  They should not be viewed as a first layer of defense, but as a second (“backup”) layer of defense:

* bats
* chimney swifts
* swallows
* flycatchers (these are migratory and don’t live here all year around)
* Nighthawks and nightjars
* dragonflies
* damsel flies
* spiders
* toads
* frogs


Larva predators

Note: these are the most effective ones against mosquitoes

* gambusia (minnows)
* Predaceous diving beetles
* copeopods
* dragonfly nymphs
* damselfly nymphs
* bacillus thuringiensis (bacteria, available at home improvement stores.  Very eco-friendly but not long-lasting)
* tadpoles (many frog species)
* backswimmer (insect)
* tadpole shrimp


This report suggests that mosquitoes can “taste” when a site has gambusia minnows and will not deposit eggs there (indirectly controlling WHERE eggs are laid).


And for those who like hard science, a very readable study from Europe on “who eats whom in a pond.”


Something that I continue to look into is “what nectar sources do mosquitoes favor?”  The adults use nectar (blood is only used by females and only when they are ready to lay eggs) as a rule — surely there’s flower shapes that they can’t utilize well.  Reduce the food for adults, and you help reduce the population.



National Science Foundation: Emerging Vector-Borne Diseases Create New Public Health Challenge

Press Release 12-218
Emerging Vector-Borne Diseases Create New Public Health Challenge

Land-use change, globalization of trade and travel, and social upheaval drive emergence of diseases

Close-up photo of a tick.

Vector-borne diseases are transmitted by ticks, mosquitoes and fleas.
Credit and Larger Version

November 30, 2012

Human activities are advancing the spread of vector-borne, zoonotic diseases such as West Nile virus, Lyme disease and dengue fever, report scientists publishing a series of papers today in the journal The Lancet.

Vector-borne zoonotic diseases result from disease-causing agents or pathogens that naturally infect wildlife, and are transmitted to humans by carriers such as mosquitoes and ticks. In short, they’re diseases transmitted between animals and humans.

Widespread land-use change, globalization of trade and travel, and social upheaval are driving the emergence of zoonotic diseases around the world, said biologist Marm Kilpatrick, who studies the ecology of infectious diseases at the University of California, Santa Cruz.

Kilpatrick co-authored one of several papers in The Lancet, along with Sarah Randolph of the University of Oxford. The Lancet papers are part of a special series in the journal focused on emerging zoonotic diseases.

“Increasing human population, and the urbanization and agricultural intensification of landscapes, put strong selective pressure on vector-borne pathogens to infect humans–and to be transmitted by vectors and hosts that live around humans,” Kilpatrick said.

“Humans are altering the environment and moving ourselves and other organisms around the globe at an ever-increasing pace,” said Sam Scheiner, a program director for the Ecology and Evolution of Infectious Diseases (EEID) program at the National Science Foundation. “Our fast-track has led to a growing disease threat.”

EEID is a joint effort with NSF and the National Institutes of Health. At NSF, the Directorate for Biological Sciences and Directorate for Geosciences fund the program.

EEID funded much of the research discussed in The Lancet papers. “These papers show how and why zoonotic diseases are emerging, and what we need to know to ease the disease burden,” said Scheiner.

The papers “offer a bridge between ecologists and clinicians whose combined efforts are needed to address the ongoing challenges of emerging zoonotic diseases,” said Kilpatrick.

Added scientist Peter Daszak, president of the EcoHealth Alliance in New York City and author of a paper in the series, “Pandemic zoonoses such as SARS, Ebola and HIV/AIDS are devastating when they emerge. What this series shows is that we have new ways of predicting their origins, of discovering them even before they reach our population–truly a brave new world for pandemic prevention.”

There are roughly two types of emerging infectious diseases: introduced and locally emerging.

Introduced diseases arise from the spread of a pathogen to a new location, as when West Nile virus arrived in New York in 1999 and subsequently spread across North America.

Locally emerging diseases increase in importance in areas where they are endemic, as with Lyme disease in the United States during the past three decades.

These two types of emerging diseases can differ markedly with respect to infection dynamics or the number of cases over time, Kilpatrick said.

“Introduced diseases often cause a big spike in infections, and then decrease substantially. Locally emerging diseases often show a steady, sustained rise.”

The movement of pathogens by global trade and travel results in the emergence of diseases in new regions.

Once established, introduced pathogens often evolve to take advantage of their new environments, including new hosts and vectors.

With much of the landscape shaped by human activities, pathogens may thrive by infecting hosts and vectors that do well in man-made environments.

Emergence of endemic vector-borne diseases can result from changes in land use, such as movement of people into new habitats, or environmental changes that affect wild animals that serve as natural hosts–and the insect vectors that spread the disease to humans.

Although vector-borne diseases are sensitive to climate, climate change does not appear to be a major driving force behind emerging diseases.

“So far, climate change has been a relatively minor player compared to land use and socioeconomic factors in the emergence of vector-borne disease,” Kilpatrick said.

Social and economic changes, ranging from economic downturns to displacement of populations by armed conflict, frequently precipitate disease outbreaks through their effects on public health systems, sanitation systems, behavioral patterns and uses of natural environmental resources.

The incidence of any vector-borne disease involves a complex interplay of multiple factors affecting animal hosts, vectors and people.

Kilpatrick and Randolph emphasize that control of these diseases requires combined efforts by clinicians and public health officials to treat patients; promote behavior likely to minimize the risk of infection; and advise on efforts to reverse the ecological drivers of transmission through vector control, urban planning and ecological restoration.

The Lancet papers are published ahead of a special 20th anniversary symposium to be held on Dec. 11 and 12, 2012, in Washington, D.C.

The symposium is hosted by the National Academies’ Institute of Medicine’s Forum on Microbial Threats. The symposium will take a retrospective look at the Institute of Medicine’s 1992 report on Emerging Infections and its 2003 report on Microbial Threats to Health, as well as its creation of the forum in 1996.


Media Contacts

Cheryl Dybas, NSF (703) 292-7734

Tim Stephens, UCSC (831) 459-2495

Anthony Ramos, EcoHealth Alliance (212) 380-4469

Related Websites
NSF-NIH Special Report: Ecology and Evolution of Infectious Diseases:
West Nile Virus Transmission Linked with Land-Use Patterns and “Super-spreaders”:
Social Bats Pay a Price: Fungal Disease, White-Nose Syndrome … Extinction?:
Controlling the Spread of Diseases Among Humans, Other Animals and the Environment:
Snails in the Waters, Disease in the Villages:

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.


 Get News Updates by Email 

Useful NSF Web Sites:

NSF Home Page:
NSF News:
For the News Media:
Science and Engineering Statistics:
Awards Searches:



Why We Need Insects–Even "Pesky" Ones

Press Release 12-189
Why We Need Insects–Even “Pesky” Ones

Hard evidence of evolution: a five-year study shows that plants may quickly lose important traits through evolution soon after insects are removed from the environment

Photo of yellow flowers of evening primrose in Ithaca, New York.

A large natural population of evening primrose (yellow flowers) in Ithaca, New York.
Credit and Larger Version

October 4, 2012

View a video interview with Anurag Agrawal of Cornell University.

At first blush, many people would probably love to get rid of insects, such as pesky mosquitoes, ants and roaches. But a new study indicates that getting rid of insects could trigger some unwelcome ecological consequences, such as the rapid loss of desired traits in plants, including their good taste and high yields.

Specifically, the study–described in the Oct. 5, 2012 issue of Science and funded by the National Science Foundation showed that evening primroses grown in insecticide-treated plots quickly lost, through evolution, defensive traits that helped protect them from plant-eating moths. The protective traits lost included the production of insect-deterring chemicals and later blooms that gave evening primroses temporal distance from plant-eating larvae that peak early in the growing season.

These results indicate that once the plants no longer needed their anti-insect defenses, they lost those defenses. What’s more, they did so quickly–in only three or four generations.

Anurag Agrawal, the leader of the study and a professor of ecology and evolutionary biology at Cornell University, explains, “We demonstrated that when you take moths out of the environment, certain varieties of evening primrose were particularly successful. These successful varieties have genes that produce less defenses against moths.”

In the absence of insects, the evening primroses apparently stopped investing energy in their anti-insect defenses, and so these defenses disappeared through natural selection. Agrawal says that he was “very surprised” by how quickly this process occurred, and that such surprises, “tell us something about the potential speed and complexities of evolution. In addition, experiments like ours that follow evolutionary change in real-time provide definitive evidence of evolution.”

Agrawal believes that his team’s study results are applicable to many other insect-plant interactions beyond evening primroses and moths.  Here’s why: The ubiquitous consumption of plants by insects represents one of the dominant species interactions on Earth. With insect-plant relationships so important, it is widely believed that many plant traits originally evolved solely as defenses against insects. Some of these anti-insect plant defenses, such as the bitter taste of some fruits, are desirable.

“This experimental demonstration of how rapid evolution can shape ecological interactions supports the idea that we need to understand feedbacks between evolutionary and ecological processes in order to be able to predict how communities and ecosystems will respond to change,” said Alan Tessier, a program director in NSF’s Directorate for Biological Sciences.

“One of the things farmers are trying to do is breed agricultural crops to be more resistant to pests,” said Agrawal. “Our study indicates that various genetic tradeoffs may make it difficult or impossible to maintain certain desired traits in plants that are bred for pest resistance.”

In addition, oils produced by evening primroses have been used medicinally for hundreds of years and are beginning to be used as herbal remedies. Agrawal’s insights about pests that attack these plants and about chemical compounds produced by these plants may ultimately be useful to the herbal and pharmaceutical industries.

Agrawal says that most previous real-time experiments on evolution have been conducted with bacteria in test tubes in laboratories. “One of things we were excited about is that we were able to repeat that kind of experiment in nature. You can expect to see a lot more of this kind of thing in future. We will keep our experiment running as a long-term living laboratory. ”

More information about this study is available from a Cornell University press release.


Media Contacts

John Carberry, Cornell University (607) 255-5353

Lily Whiteman, National Science Foundation (703) 292-8310

Program Contacts

Alan Tessier, National Science Foundation (703) 292-7198

Principal Investigators

Anurag Agrawal, Cornell University (607) 254-4255

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.


 Get News Updates by Email 

Useful NSF Web Sites:

NSF Home Page:
NSF News:
For the News Media:
Science and Engineering Statistics:
Awards Searches:



Tarrant County’s guide to Gambusia (mosquito fish)

This humble little Texas minnow is one of the primary resources used by cities to fight mosquitoes — and they do a very good job of it, too.   They don’t come in pretty colors and they never get very large (up to 2 inches for females) but each fish can eat over 100 mosquito larvae in a day.  This makes them an ideal method of controlling mosquitoes, since when they’re in the larval or egg stage, mosquitoes don’t move about much and they float on top of the water.  They’re easier for predators such as the gambusia to spot… and eat.  Once they hatch out and are flying around, they’re much harder to catch, even for quick chimney swifts and other birds that catch flying insects. And they are the mosquito control method preferred by many Texas cities.


But this year in North Texas, the much-needed fish were in very short supply due to problems with the hatchery, leaving cities scrambling to find other sources — or resorting to spraying techniques (which residents don’t like.)


For people interested in these fish, Tarrant County has a local stocking guide for city governments that can be applied on a smaller scale.

Homeowners with ponds can get these fish from Keller Fish Farms:


Current Community Science Projects


The Arlington Archosaur site is closing for the remainder of the summer (as is usual) — in August it’s just Too Darned Hot to dig.  They will return later in the year.

Trinity River Audubon Center’s Third Thursday will have Frogwatch, Amphibian Watch, and National Phenological Database expedition as well as a Chimney Swift watch and possibly an Owl Prowl (whew!)  This time we’ll also be doing a “transect survey” for dragonflies.

Botannical Research Institute of Texas (BRIT) has an ongoing need for volunteers to help with their databases (indoor work!) and do some field research.  Contact them for details.


GENERAL EDUCATION, public welcome

Connemara Conservacy has an astronomy walk (August 18th) and an evening Open House (September 23.)  See website for details.

The John Bunker Sands Wetland Center has a First Saturday Walk & Talk Bird Tour.    9:00 – 11:00 am; $10 includes admission if you’re not a member; $5 for members.

Botannical Research Institute of Texas (BRIT)’s Science Saturday – open plant ID, exhibits, demonstrations, tours, etc First Saturday of every month at  10:00 – 2:00.  This is a fun place to visit, even if you’re not really into plants.



The John Bunker Sands Wetland Center is planning to start some Citizen Science initiatives in the near future.  I will be in a planning meeting about this effort at the end of August.


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Defining Dallas: Does Drought Increase Acid Rain Effects?

     Acid Rain was one of the big “bugbears” of my youth — a keyword that caught our attention along with pictures of dying trees.  Legislative action in the 1970’s (reinforced by the Clean Air Act) helped turn things around, and ponds and lakes began recovering.  Acid rain was an issue of the past.


We’re in the middle of a second year of drought here in Texas, and the drought monitor shows that we haven’t had enough rainfall to make up for the deficits. I’m watching the ponds dry up again at Trinity River Audubon Center and am setting up some trees as monitoring stations to start making measurements of just how much trouble the vegetation is having.  If the research published in the journal Water Resources Research, Charles Driscoll of Syracuse University and the National Science Foundation’s (NSF) Hubbard Brook Long Term Ecological Research (LTER) site in New Hampshire is indicating a trend, counties suffering from the drought are soon going to be hit with a double whammy when the rains return.

Photo of a stream with boulders in the streambed.

New England’s ecosystems have rebounded from the disastrous situation of the 1950’s only to be faced by issues caused by today’s higher atmospheric carbon dioxide level and its atmospheric fallout.  Warmer temperatures and an increase in carbon dioxide is changing the pattern and quality of water in forested areas, and a model used by Hubbard Brook predicts that snowfall at Hubbard Brook will begin later in winter, snowmelt will happen earlier in spring, and soil and stream waters will become acidified — and we’re back to the Acid Rain problem again.

Here’s the kicker: In scenarios that look decreases in summer soil moisture due to shifts in hydrology (as in, “drought”), the end result is further acidification of soil and water.

Last year, I saw crusts of salt along the ponds here in Dallas as they dried out.  I’m not seeing that yet, but the report suggests to me that it might be a very good time for an increase in citizen science monitoring of our waterways.  Fellow Texans interested in this can contact the Texas Stream Team.  I’ll be getting training for this sometime in the near future, so it may be added to the Trinity River Audubon Center’s Third Thursday Science Programming.

Community Science Initiatives logo

Related Websites
NSF LTER Network:
NSF Hubbard Brook LTER Site:
Science, Engineering and Education for Sustainability NSF-Wide Investment (SEES):




Crikey! It’s a croc!


There’s all sorts of timeless truths that people offer, like “Life’s short — eat dessert first” and “Never pass up a chance to go help dig up a crocodile.” Maybe the second one isn’t quite as tried and true as the first one, but I’m a firm believer in never passing up a chance to get out in the sun and do some research. So, when the opportunity came up to help dig out a croc skull at the Arlington Archosaur site, I madly shuffled my schedule so I could head out.

You never know when you’ll get another chance to work on a croc, right?

Derek’s got an Earthforce team there for the next 10 days or so — a really fun pack of high school seniors from the Los Angeles area who aren’t afraid to get out and get hot and sweaty and dirty in the name of paleontology.

We were onsite and ready to roll at 10:30 am (Derek took them to a local lake to show them the geology first, and then back to the site.  He gave them a good overview of what’s out here and then assigned them dig jobs.  Some of them surveyed an area for fossils, others helped us dig at the croc skull area, and still others sifted dig soil for fossils.  Since I’m an experienced fossil preparator, I started work on clearing the ground around the back of the jaw, part of the preparation to get it to sit up on its own little “island.”  Once it’s isolated from the rest of the ground, they will finish digging underneath and then remove the block of peaty rock and fossil as a single “lump.”  Back in the lab, preparators like myself finish the fun of digging the whole thing out of the matrix with a variety of tools.

Derek and the Earthforce gang at the site

Derek and the Earthforce gang at the site

I love this sort of work — it’s CSI Earth — ancient forensics.  You go slowly and carefully, but the excitement of seeing something that has never been seen before by human eyes never wears off.  My favorite tools for this kind of formation is actually paint scrapers because I can take off very thin layers of the matrix and be very gentle about it.

The croc site team, carefully trenching the fossils

It looked for awhile like we might have the upper half of the skull as well, but what looked like bone turned out to be the ubiquitous sheets of calcite crystals.  They lie, like bits of clear cellophane throughout the layer, and when you pick catches one, it scratches to the white color of bone. Sometimes you spend ten minutes digging an intriguing bit of something only to discover it’s still another calcite crystal.

Right now, we’ve just got the right side of the jaw of an adolescent (teenaged) croc. The other half of the jaw may be somewhere underneath, but I won’t be able to get out there again until long after this skull has been worked out of the ground.

As is typical with many public archaeology and paleontology digs, we called a halt at 2 pm, just before the hottest part of the day.  But there’s more crocs out there, and as schedule permits, I’ll find another day to get out there and play with 90 million year old crocodiles.

You can find out more about the Arlington Archosaur site here:


National Science Foundation Press Release: West Nile Virus Transmission Linked with Land-Use Patterns and "Super-spreaders"

One of the three birds that are most commonly associated with West Nile virus is the robin (the other two are blue jays and crows.)  Infected jays and crows typically die within 3-4 days, but robins can live much longer with this illness.

Now the National Science Foundation has published some information about land use and the spread of West Nile Virus.

Press Release 11-229
West Nile Virus Transmission Linked with Land-Use Patterns and “Super-spreaders”

Spread highest in urbanized and agricultural habitats

Image of an American robin.

American robins play a key role in the spread of West Nile virus.
Credit and Larger Version

October 20, 2011

After its initial appearance in New York in 1999, West Nile virus spread across the United States in just a few years and is now well established throughout North and South America.

Both the mosquitoes that transmit it and the birds that are important hosts for the virus are abundant in areas that have been modified by human activities.

As a result, transmission of West Nile virus is highest in urbanized and agricultural habitats.

“The virus has had an important impact on human health in the United States partly because it took advantage of species that do well around people,” said Marm Kilpatrick, a biologist at the University of California, Santa Cruz, who studies the ecology of infectious diseases.

West Nile virus can infect a wide range of animals, including more than 300 species of birds and 60 species of mosquitoes. It also infects mammals, reptiles and even amphibians.

But researchers have found that in most places only a few key species of bird “hosts” and mosquito “vectors” are important in transmission of the virus.

“We now know that in any given location, only one or two species of mosquitoes play a big role, and only a handful of birds appear to be important in overall transmission rates,” said Kilpatrick, who reviewed a decade of research on the ecology and evolution of West Nile virus in a paper published in this week’s issue of the journal Science.

According to Kilpatrick, the familiar American robin plays a key role in the transmission of West Nile virus across much of North America.

It is such an important host species that Kilpatrick calls robins “super-spreaders” of West Nile virus.

The reason is not so much the abundance of robins, but rather the feeding patterns of the mosquitoes that transmit the virus.

Mosquito species important in transmission seem to prefer robins over other, more abundant species of birds such as house sparrows.

“Robins are more important in transmission than their abundance alone would suggest,” Kilpatrick said.

“The peculiar feeding habits of the vectors play a really important role in transmission, and this idea applies to many different diseases. It’s one of the really interesting things we’ve learned from the past decade of research on West Nile virus.”

Insights gained from research on West Nile virus could help public health officials deal with other introduced diseases in the future.

“The spread of disease-causing organisms is likely to only increase in the coming years,” said Sam Scheiner, director of the Evolution and Ecology of Infectious Diseases program at the National Science Foundation (NSF). The program is a joint effort of NSF and the National Institutes of Health (NIH).

“West Nile virus has provided a test of our ability to respond to such spread,” Scheiner said. “This research shows that predicting disease incidence in humans and other animals is more complex than first imagined, but that greater understanding of such complexities is possible–knowledge that can be applied to the next threat.”

The globalization of trade and travel has spread many invasive species, including infectious pathogens like West Nile virus.

Although its exact route of entry to New York is unknown, West Nile virus may have arrived in an infected mosquito carried across the Atlantic in an airplane.

The virus then adapted quickly to its new environment, evolving a new strain that was transmitted more efficiently by local mosquitoes than the introduced strain. By 2005, the new strain had completely displaced the introduced one throughout North America.

Three species of mosquitoes are key vectors for transmitting West Nile virus in much of North America. Interestingly, these mosquitoes are not among the species that feed frequently on people.

They are bird specialists that happen to bite people often enough to cause human infections.

“The mosquitoes that bite humans most are actually not as important in transmission of West Nile virus to humans because they rarely bite birds and thus rarely get infected in the first place,” Kilpatrick said.

“Instead, it’s the species that feed mostly on birds and frequently get infected, but occasionally feed on people, that are most important.”

Millions of birds have died from West Nile virus infection, with dramatic effects on the populations of some species. Crows, for example, are much less abundant than they were before the virus arrived.

The robin population, which had been growing rapidly, has leveled off.

“Robins were on a steady upward trajectory thought to be linked to human land use–they love lawns and agricultural fields,” Kilpatrick said.

“Crow populations were growing even faster.  Now crow populations have crashed downward and robins have leveled off, and we suspect that’s due to West Nile virus.”

The worst human outbreaks of West Nile virus in the United States occurred in 2002 and 2003.

According to Kilpatrick, it’s not clear whether the reduction in human disease since then represents a long-term trend or short-term variability.

“It may be that with climatic conditions favorable for the virus we could again get very intense years of transmission,” he said.

“We don’t know yet how much of the year-to-year variation can be explained by climatic conditions or other factors, such as acquired immunity in birds or humans.”

Many other diseases caused by mosquito-borne or tick-borne viruses could potentially be introduced to the United States from overseas, Kilpatrick said.

Understanding the ecology of these viruses may lead to strategies that could prevent a newly introduced pathogen from establishing itself as successfully as West Nile virus.


Media Contacts

Cheryl Dybas, NSF (703) 292-7734

Tim Stephens, UCSC (831) 459-2495

Related Websites
NSF Special Report: The Ecology of Infectious Diseases:

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2011, its budget is about $6.9 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives over 45,000 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly.


 Get News Updates by Email 

Useful NSF Web Sites:

NSF Home Page:
NSF News:
For the News Media:
Science and Engineering Statistics:
Awards Searches: