Backyard Orchard News
Walnuts are packed with vitamins, minerals and antioxidants, right?
And sometimes a little protein.
Protein, as in larvae. That's not a welcome sight.
Sometimes you'll find two or three navel orangeworm (NOW) larvae inside a single walnut, along with copious amounts of webbing and frass.
We once stored a bucket of untreated walnuts inside a vacant outbuilding. By spring, we had larvae crawling up the walls and moths trying to find an opening and us trying to find our sanity.
Last weekend I went on The Great Navel Orangeworm Search. I collected three walnuts that had fallen onto the sidewalk. Two of the walnuts were perfect. Drats!
Ah, but when I cracked open the third, I spotted the larvae.
Three larvae inside the third walnut on the third of January at 3 o'clock in the afternoon.
UC Davis entomology professor Frank Zalom said the best way to tell if the larvae are navel orangeworm is "to check for the presence of a crescent-shaped marking on the sides of the second segment behind the head."
The larva of the codling moth doesn't have this marking.
NOW is no friend of walnut growers. The moths deposit their eggs inside the mummy nuts--the ones left on the trees after a harvest--or the fallen nuts. Next season: more trouble. Economic trouble.
A pest of both fruits and nuts, NOW was first found in navel oranges; thus the name.
As for the three larvae I found inside the walnut, as soon as I split the hull, they were off and running.
Or rather, off and crawling.
Larvae Inside Walnut
In a Nutshell
Entomology folks at UC Davis remember when Louie Yang was a doctoral candidate, studying population biology with major professor Rick Karban.
Yang received his doctorate in 2006 and then became a UC President's Postdoctoral Fellow in the Department of Ecology, Evolution and Marine Biology at UC Santa Barbara.
Now he's back.
Yang joined the UC Davis Department of Entomology as an assistant professor on Jan. 2.
“Louie is one of our rising stars,” said Lynn Kimsey, chair of the Department of Entomology and director of the Bohart Museum of Entomology. “His work on resource pulses has led to the creation of a new field of ecological study.”
“It’s great to be back,” Yang said. “UC Davis is truly one of the best places on the plant to study ecology, and it’s an honor to be a faculty member here. I’m looking forward to it immensely.”
Yang’s research interests include community ecology, species interactions, temporal variation, extreme events in nature, and the integration of ontogeny and phenology.
“My research program studies how resource pulses, disturbance events and the timing of species interactions affect ecological communities,” Yang said. “I describe myself as a community ecologist. Much of my research is aimed at understanding the temporal dimension of ecological communities: How do natural systems respond to changing conditions?”
His work emphasizes “the fundamental idea that ecological systems are constantly changing over multiple time scales.”
“I investigate community responses to ecological perturbations along a continuum of temporal scales, including extreme events as well as longer time-scale climate changes.”
Yang said a mechanistic understanding of how communities respond to changing conditions “is relevant to several conceptually and socially important issues in ecology.”
Yang’s lab and office are at 380 Briggs Hall.
His wife, Tabatha Yang, is the former children’s program manager at the Santa Barbara Museum of Natural History. Beginning this year, she is engaging in public outreach for two UC Davis museums, the Museum of Wildlife and Fish Biology, and the Bohart Museum of Entomology.
We're all expecting great things of Louie Yang and Tabatha Yang.
Here's to 2009! And to great careers!
There she was, snuggled beneath a garbage can lid, seeking warmth as temperatures dipped to freezing levels.
She was lucky.
It was City Garbage Pick-Up Day. She could have been trucked to the local landfill had we not rescued her.
Luck be a lady and she was.
The little lady, aka ladybug, aka lady beetle, aka L-bug, survived.
She'll stay in the garden.
On the Move
Off and Running
Chemical ecologists at the University of California, Davis, are changing their navel-orangeworm research direction after an elementary school student’s science project found that the major agricultural pest prefers pistachios over almonds and walnuts.
Gabriel Leal, 11, a sixth grader at Willet Elementary School, Davis, prefers pistachios over all other nuts so he figured that the navel orangeworm (NOW) would, too.
“Pistachios taste better,” reasoned Gabriel, whose family says he can eat an entire bag of pistachios at one sitting. Pistachios have long been his favorite nut, so why wouldn’t the navel orangeworm prefer pistachios over almonds and walnuts, too?
So the sixth grader hypothesized that the insect would lay more eggs in pistachios than in almonds and walnuts, contrary to widely published research that indicates an almond preference.
“Everybody knows that navel orangeworms prefer almonds,” said his father, Walter Leal, a chemical ecologist and professor of entomology at UC Davis. Research published recently in the California Agriculture journal also indicates the preference.
“But in science,” Leal said, “we should believe what we see, not what others tell us. I know that Gabriel prefers pistachios, but I assumed the navel orangeworm’s taste receptors were different.”
Wrong. Gabriel’s research showed that the insects preferred pistachios, just like him.
The findings led to a report at the Almond Board of California’s 32nd Almond Industry Conference, held Dec. 1-2 in Modesto, and launched a new direction of navel orangeworm chemical ecology research at UC Davis
Gabriel performed his research in his father’s UC Davis lab, under the volunteer supervision and mentoring of chemical ecologist Zain Syed.
“It was a ‘choice’ experiment where Gabriel placed mated and gravid (egg-filled) females in a cage,” Syed said. “He used four commercially available navel orangeworm traps (Ovitraps). One trap was filled with 50 grams of shelled pistachios, another with 50 grams of almonds, and the third with 50 grams of walnuts. The empty trap served as the control to check if the trap itself had any effects on attracting egg-laying moths. The eggs laid in the ovitraps were counted for two consecutive nights.”
Said Leal: "Gabriel got enough replicates to demonstrate that female orange navelworms do prefer pistachios over walnuts and almonds. We are very excited with our little scientist’s discovery. I reported ‘our’ findings at the state almond industry conference in Modesto. And these findings changed our research direction, because we are now interested in determining what chemistry in pistachios attracts female navel orangeworms.”
“Oviposition (egg-laying) attractants derived from almond oil are used to monitor female populations in the field,” Leal explained, “but during hull split, the chemical from the natural source (crop) competes with the synthetic material in traps. If we use pistachio-derived attractants in the almond field there will be no competition throughout the flight season.”
So how significant a pest is the navel orangeworm?
According to research entomologist Brian Higbee of Paramount Farming, Bakersfield, "it is the primary and most destructive pest on almonds and pistachios." California has some 152,000 acres planted in pistachios, while the state's almond acreage totals more than 700,000.
"The economic impact of NOW damage varies from year to year, but it can easily reach $10-15 million for our company and much higher statewide," Higbee said.
The take-home message? "Well, in science we should never underestimate anyone's idea,” Leal said. “That's why the academic environment is so enriching: students come with new ideas, but I never imagined we would benefit so much from a science project for elementary school."
For more, see news story on the UC Davis Department of Entomology Web site.
Young scientist Gabriel Leal
Twenty-nine days to go.
If you love bees and know how to design a bee friendly garden, remember Jan. 30.
Jan. 30 is the deadline to submit your design for the half-acre bee friendly garden at the Harry H. Laidlaw Jr. Honey Bee Research Facility, UC Davis. The nationwide competition is funded by Häagen-Dazs.
This will be a pollinator paradise that will meet the nutritional needs of honey bees and serve as a living laboratory.
"It will provide a much needed, year-around food source for our bees," said Lynn Kimsey, chair of the Department of Entomology and director of the Bohart Museum of Entomology. "We anticipate it also will be a gathering place to inform and educate the public about bees."
The UC Davis Department of Entomology Web site lists the rules, the prizes, and provides a list of bee-favorite flowering plants. Plans call for "something" to be blooming throughout the year.
The long list of flowering plants includes sages, toyon, catmint and lavender.
To that I'd add the rock purslane (Calandrinia grandiflora). In our own bee friendly garden, that's a favorite of the bees. And guess what? It's blooming right now, in the dead of winter. Ray Lopez, owner of El Rancho Nursery, Vacaville (where we bought the plant), says it blooms throughout the year in California.
We haven't seen the bees lately, but the rock purslane is waiting for them.
Close-up of Bee