Backyard Orchard News
Chemical ecologist Walter Leal, professor and former chair of the UC Davis Department of Entomology, and his postdoctoral researcher Zain Syed have done it again.
In August of 2008, they discovered the secret mode of the insect repellent, DEET. In groundbreaking research published in the Proceedings of the National Academy of Sciences (PNAS), they found that DEET doesn't mask the smell of the host (that would be you and me), nor does DEET jam the insect's senses.
Mosquitoes CAN indeed smell DEET. They avoid it because they don't like the odor.
Then on Monday, Leal and Syed published more groundbreaking research, also in PNAS. They identified the dominant compound that attracts Culex mosquitoes to both birds and humans.
It's a compound called nonanal, naturally produced in birds and humans. This not only explains the host shift from birds to humans, but paves the way for key developments in mosquito and disease control.
Infected Culex mosquitoes transmit life-threatening diseases, including West Nile virus. Since 1999, the Centers for Disease Control and Prevention has recorded 29,397 human cases and 1,147 fatalities in the United States alone.
“Nonanal is how they find us,” Leal said. “The antennae of the Culex quinquefasciatus are highly developed to detect even extremely low concentrations of nonanal.”
Researchers from throughout the country this week praised their work.
Yale University professor John Carlson, a leading scientist in insect olfaction, described the study as “exciting with important implications for the intriguing question of how mosquitoes find the humans they bite.”
“Leal and Syed have identified a human odor that is detected with great sensitivity by the antennae of mosquitoes that transmit West Nile virus,” Carlson said. “In addition to its scientific interest, the study may have important practical applications in the control of these mosquitoes and the diseases they carry.”
Chemical ecologist Coby Schal, a professor at North Carolina State University, described the research as representing “some of the best research on insect olfaction that I have ever read. By combining trapping experiments in the field with careful characterization of the response profiles of antennal and maxillary sensilla of Culex mosquitoes, Syed and Leal show not only that the combination of carbon dioxide and nonanal is an important beacon for blood-seeking mosquitoes, but also that a large fraction of the sensilla on the mosquito’s nose (antennae) is dedicated to the detection of nonanal at incredibly low concentration.
“Such high sensitivity of olfactory receptor neurons to nonanal – rivaling the response characteristics of pheromone responsive neurons – suggests that nonanal has played an important role in the evolution of host-finding and host-preferences in Culex mosquitoes,” Schal said. “This is a truly exceptional achievement by the outstanding Syed/Leal team, but in step with their previous outstanding contributions on a wide range of arthropods.”
More information on the Leal lab research is on the Department of Entomology Web page.
Leal, a newly elected Fellow of the Entomological Society of America (he's one of 10 entomologists to be so honored this year) and Syed, named one of the top post-doctoral researchers at UC Davis this year, have indeed done it again.
When you think of all the havoc that mosquito-borne diseases have wreaked, this is the kind of research that definitely deserves a round of applause.
Dr. Leal and Dr. Syed are a highly efficient and effective SWAT team.
Walter Leal and Zain Syed
A bee is a bee is a bee?
Poet Gertrude Stein ("a rose is a rose is a rose") could have said that.
True, there's only one species of honey bee in the United States--Apis mellifera, the Western or European honey bee--but there are several races.
The "gold standard" is Apis mellifera ligustica, also known as the Italian honey bee, the most common bee in America. It's basically your yellow or golden bee.
But among the other popular races is Apis mellifera carnica, aka the Carniolans or "Carnies," a darker bee. It is primarily darkish gray.
We spotted both of them last weekend sharing a lavender--the blond Italian bee on one side and the darker Carniolan bee on the other.
Author Richard E. Bonney writes in his book, Beekeeping: A Practical Guide: "For the most part, they (the races) are the result of evolution in geographic isolation (Italians on the Italian peninsula, for instance) where the specific climate and vegetation influenced their development over the ages. Each race has specific traits that relate to the geographic origin of that race."
At UC Davis, bee breeder-geneticist Susan Cobey, manager of the Harry H. Laidlaw Jr. Honey Bee Research Facility, focuses her research on identifying, selecting and enhancing honey bee stocks that show increasing levels of resistance to pests and diseases. In the early 1980s, Cobey developed her New World Carniolans stock by back-crossing stocks collected from throughout the United States to create a more pure strain.
“Over time, it has proven very productive, winter hardy, well-tempered and more resistant to pests and disease,” says Cobey, who teaches advanced courses on queen bee rearing and queen bee insemination, drawing students from throughout the world.
Genetic diversity, the raw tools for selection, is critical “in maintaining colony fitness and resisting pests and diseases,” she notes.
No matter the races, the honey bees still race for the lavender.
And the other bee friendly plants...
The Italian and the Carniolan
Fran Keller, a doctoral candidate in entomology, and Nanase Nakanishi, a senior animal science major, teamed to create a "Save the Bees" T-shirt, spotlighting the Harry H. Laidlaw Jr. Honey Bee Research Facility and the adjacent Häagen-Dazs Honey Bee Haven.
The newly planted haven is a half-acre bee friendly garden designed to provide a year-around food source for honey bees and an educational experience for human visitors. By spring, it will be well-established and in full bloom.
And the T-shirt? Nakanishi served as the artist, and Keller, the designer.
Nakanishi, a Bohart student employee for the past three years, plans to become a veterinarian.
Keller's Ph.D. work involves tenebrionids or darkling beetles. She studies with major professor Lynn Kimsey, director of the Bohart and professor and vice chair of the Department of Entomology.
In her "spare" time, Keller has created a number of insect posters and T-shirts, all available at the museum.
The bee shirt, which comes in black or yellow, is receiving scores of accolades. "Cute!" is one of them.
The front says "Save the Bees" and is inscribed with the Laidlaw facility name. The back features a photo (taken by yours truly) of a newly emerged bee tucked inside the line drawing of a hive. It is lettered with "Follow me to the Honey Bee Haven Garden!"
Keller said the shirts will sell for $20 for adults and $15 for youths, and range in size from 2XL to small for adults, and XS to large for youths.
All proceeds are earmarked for honey bee research at UC Davis. The shirts are available at the Bohart Museum, 1124 Academic Surge, UC Davis campus, or by accessing the Bohart Web site.
Saving the Bees
The dull brown moth may be dull-looking but as noctuid cutworms they're not.
We spotted this noctuid cutworm, soon to be a dull brown moth, last week on a yarrow in the Storer Gardens at the University of California, Davis.
Noctuids belong to--guess what--the Noctuidae family, which includes moslty the dull-colored moths.
You're likely to see these moths flying around at night, attracted to your porch light.
Another place you can see these moths--as specimens--is the Bohart Museum of Entomology, 1124 Academic Surge, on the UC Davis campus. Directed by Lynn Kimsey, professor and vice chair of the department, the Bohart Museum houses some seven million insect specimens--and a few live ones, such as Madagascar hissing cockroaches. Yes, they give tours. Contact Tabatha Yang at email@example.com.
What's really interesting about the noctuids is that they have auditory organs that are capable of detecting frequencies from 3 to more than 100 kilocycles per second. This can save them from being bat prey.
Bats, you see, emit high-pitched chirps as they fly around at night seeking prey and avoiding obstacles. The chirps bounce back or echo, enabling them to maneuver in complete darkness.
When the dull brown moths hear the chirps, they fold their wings and drop to the ground.
Three kilocycles (3000 cycles) per second is in the top octave of the piano; the average upper limit of hearing in humans is about 15 kilocycles per second. (Source: An Introduction to the Study of Insects by Donald Borror and Dwight DeLong, former entomologists at Ohio State University)
Dianne DiBlasi did it.
Back in January, we wrote a Bug Squad blog about Dianne DiBlasi’s three-year effort to overturn an Allendale, N.J. ban on backyard beekeeping.
DiBlasi, who leads a group of teen environmentalists known as Team B.E.E.S. (Bergen Environmental Effort to Save Bees) and is a member of the the New Jersey Beekeepers' Association, simply wanted the Allendale Council to remove bees from the city’s list of “banned and dangerous animals” and allow non-commercial beekeepers to keep their bee colonies in their yards.
On Oct. 14, the Allendale Council unanimously voted to lift the bee ban.
This is good news indeed. It shows what one person, with help of her friends and fellow beekeepers, can do to overturn an ordinance that needed overturning.DiBlasi set out to educate the town officials and the community about how vital honey bees are. She pointed out that bees are important pollinators, that they pollinate one-third of the food we eat. She pointed out that bees are in trouble, due to the mysterious malady known as colony collapse disorder, and diseases, parasites, pests, pesticides, malnutrition, and climate changes. She pointed out that bees need our help and one way to help is to plant bee friendly gardens and allow backyard beekeeping.
Of course, the lifting of the bee ban comes with restrictions, such as the number of hives within a certain area. There are also requirements such as notifying the neighbors within 200 feet of any property line (if a neighbor protests, no beekeeping), protecting the area with a fence at least six feet high, licensing the hives with the Allendale officials, registering with the New Jersey apiarist, and the like.
But she did it!
DiBlasi graciously thanked the entire council for their support. "I promise you that you will be amazed at your flower gardens and vegetable gardens. Give me two years."
We suspect it will be a lot less.
Newly emerged bee