Email Print Site Map
Cooperative Extension San Joaquin County
University of California
Cooperative Extension San Joaquin County

UC Blogs

Partnering with The Pieris Project

If you see a white cabbage butterfly fluttering by you, net it.

The Pieris Project wants it.

Entomology Today, a publication of the Entomological Society of America, today covered a story about how graduate students (including Sean Ryan of the University of Notre Dame, Indiana, and Anne Espeset, University of Nevada, Reno), are seeking a "global community of citizen scientists" to collect the white cabbage butterfly, Pieris rapae, for their Pieris Project, launched last summer to study invasion biology and species responses to environmental change.

They've already received more than 600 species from "at least half of the United States," and eight other countries, Entomology Today reports.  The butterfly, native to Europe, has spread throughout the world in the last 200 years and is thought to be one of the most widespread and abundant butterflies of them all. It is found on every continent except Antarctica. (Check out the most up-to-date collection map.)

The graduate students want to reconstruct the invasion history and "explore how environmental variation has been shaping the genome and phenotype of this butterfly," according to the article.

Here are some of the specifics:

1) Send them a couple of butterflies from your backyard. Include the date and latitude/longitude coordinates on the envelope. You can find more details at http://www.pierisproject.org. Even though fall is here, depending on where you live, you may be able to catch a few before winter arrives, they point out.

2) Help spread the word by either sharing the project with people you think might be interested in participating or by letting them know of organizations, schools, or any community that might be interested. Email them at pierisproject@ gmail.com.

3) Consider donating to their crowdfunding campaign. They say they have only a few days left to reach their goal, and it's all or nothing, "so we need all the help we can get! One incentive for donating is a 'Backyard Genomics Kit' — a great gift for a budding entomologist — and we also have awesome photographs by the amazing bugographer Alex Wild!" (Wild, a noted insect photographer, received his doctorate in entomology from UC Davis.)

As an aside, the cabbage white butterfly gains notoriety every year in the three-county area of Sacramento, Yolo and Solano, California.  Butterfly expert Arthur Shapiro, distinguished professor of evolution and ecology at UC Davis, sponsors an annual contest offering a pitcher of beer for the first butterfly of the year collected in one of the three counties.

The contest is all part of Shapiro's 43-year study of climate and butterfly seasonality. He monitors the many species of Central California butterflies and posts the information on his website, Art's Butterfly World.

Shapiro says the cabbage white "is typically one of the first butterflies to emerge in late winter." Since 1972--the year he launched the "beer-for-for-a-butterfly" contest--the first flight has varied from Jan. 1 to Feb. 22, averaging about Jan. 20. And he usually wins his own contest because he knows where to find them. (See Bug Squad for results of this year's contest.)

Meanwhile, let's all catch some cabbage whites for the Pieris Project.

Have you seen this butterfly? You can become a part of a global community of citizen scientists by helping graduate students with a project. (Photo by Kathy Keatley Garvey)
Have you seen this butterfly? You can become a part of a global community of citizen scientists by helping graduate students with a project. (Photo by Kathy Keatley Garvey)

Have you seen this butterfly? You can become a part of a global community of citizen scientists by helping graduate students with a project. (Photo by Kathy Keatley Garvey)

Posted on Thursday, October 30, 2014 at 9:19 PM

Good News for the Bees!

Good news for the honey bees!

And none too soon.

U.S. Department of Agriculture (USDA) Secretary Tom Vilsack announced today (Oct. 29) in a press release that "more than $4 million in technical and financial assistance will be provided to help farmers and ranchers in the Midwest improve the health of honey bees, which play an important role in crop production."

 “The future of America's food supply depends on honey bees, and this effort is one way USDA is helping improve the health of honey bee populations,” Vilsack said in the USDA release. “Significant progress has been made in understanding the factors that are associated with Colony Collapse Disorder and the overall health of honey bees, and this funding will allow us to work with farmers and ranchers to apply that knowledge over a broader area.”

The declining honey bee population is besieged with health issues, exacerbated by pests, parasites, pesticides, diseases, stress and malnutrition  Nationally, however, honey bees pollinate an estimated $15 billion worth of crops, including more than 130 fruits and vegetables. If you enjoy such produce as almonds, apples, cherries, cucumbers, and peaches, thank a bee for its pollination services.

USDA's Natural Resources Conservation Service (NRCS) is focusing the effort on five Midwestern states: Michigan, Minnesota, North Dakota, South Dakota and Wisconsin.

Why the Midwest? "From June to September, the Midwest is home to more than 65 percent of the commercially managed honey bees in the country. It is a critical time when bees require abundant and diverse forage across broad landscapes to build up hive strength for the winter."

The announcement renews and expands what USDA calls "a successful $3 million pilot investment that was announced earlier this year and continues to have high levels of interest."  It's all part of the June 2014 Presidential Memorandum – Creating a Federal Strategy to Promote the Health of Honey Bees and Other Pollinators, which directs USDA to expand the acreage and forage value in its conservation programs.

Funding will be provided to producers through the Environmental Quality Incentives Program (EQIP). Applications are due Friday, Nov. 21.

This means that the farmers and ranchers will receive support and guidance to implement conservation practices that will provide safe and diverse food sources for honey bees. This will include appropriate cover crops or rangeland and pasture management. In addition to providing good forage and habitat for honey bees and other pollinators, the actions taken are expected to reduce erosion, increase soil health and inhibit invasive species.

California also will benefit. "This year, several NRCS state offices are setting aside additional funds for similar efforts, including California – where more than half of all managed honey bees in the U.S. help pollinate almond groves and other agricultural lands – as well as Ohio and Florida," according to the release.

A nice push for the pollinators!

Honey bee foraging on mustard. (Photo by Kathy Keatley Garvey)
Honey bee foraging on mustard. (Photo by Kathy Keatley Garvey)

Honey bee foraging on mustard. (Photo by Kathy Keatley Garvey)

Posted on Wednesday, October 29, 2014 at 9:26 PM
Tags: honey bees (214), mustard (5), NRCS (1), pollinators (9), Tom Vilsack (1), USDA (2)

Anthony Cornel Knows Mosquitoes

The yellow fever mosquito, Aedes aegypti. (CDC Photo)
Medical entomologist Anthony “Anton” Cornel knows his mosquitoes--and a few snakes, too.

When he was doing research in Brazil in September, he draped a snake around his neck and posed for the camera.

His favorite research subjects, though, are mosquitoes.

Among them:

  • The yellow fever mosquito, Aedes aegypti, found throughout the tropics and subtropics and a  newly invasive species in central California.
  • The West Nile virus mosquito, Culex quinquefasciatus, found throughout much of the world.
  • The malaria mosquito, Anopheles gambiae, which wreaks worldwide havoc.

Cornel's name appeared in the news this week when the UC Davis lab of Walter Leal announced that it had found the odorant receptor that repels DEET in the southern house mosquito, Culex quinquefasciatus mosquito. Cornel provided the mosquitoes that allowed the Leal lab to duplicate his colony. Proceedings of the National Academy of Sciences (PNAS) published the work Oct. 27.

Culex quinquefasciatus transmits West Nile virus and other diseases. (Photo by Kathy Keatley Garvey)
Cornel, based at the UC Kearney Agriculture and Research Center, Parlier, and an associate professor in the UC Davis Department of Entomology and Nematology faculty, has studied mosquitoes for more than two decades. He collects, rears and researches mosquitoes from all over the world, including the United States, Mali, Cameroon, Comoros, Tanzania, South Africa and Brazil. 

Cornel's main research keys in on the population genetics and ecology of West Nile virus vectors in the United States and population genetics and ecology of major malaria vectors in Africa.

“Anton is a great asset to our program, a wonderful colleague, and a nice team player,” said Leal, a professor in the Department of Molecular and Cellular Biology.  “We benefit greatly from his generosity by sharing not only mosquito colonies, but also his encyclopedic knowledge on mosquito biology and ecology. We shared co-authorship in a number of publications, and many more are coming.”

Cornel collaborates with Leal on oviposition attraction in Culex quinquefasciatus and “we are now endeavoring to come up with effective oviposition attractive chemical lures to use in virus surveillance and kill traps.”

The malaria mosquito, Anopheles gambiae. (Photo by Anthony Cornel)
However, the mosquito that's alarming residents of central California is the yellow fever mosquito, Aedes aegypti. Infected mosquitoes can transmit dengue, chikungunya and yellow fever viruses and other diseases. 

“The invasion of Aedes aegypti into central California has been of great concern especially as current control methods do not appear to be working very well,” said Cornel, who works closely with state's mosquito abatement personnel. “We have found that the Aedes aegypti have insecticide resistance genes which likely explains why their ultra-low volume (ULV) and barrier spray applications have not worked as well as expected. Work will be ongoing next year when the Aedes aegypti become active again after a brief slow overwintering period from November to March.”

A native of South Africa, Cornel received his doctorate in entomology, focusing on mosquito systematics, in 1993 from the University of the Witwatersrand, Johannesburg. He completed a post-doctoral fellowship with the Entomology Branch of the Centers for Disease Control and Prevention (CDC), Atlanta, before joining UC Davis in 1997 as an assistant professor and researcher.

How did he get involved in mosquitoes? “My interest in mosquito research started in the mid-1980s when I agreed to conduct a masters study under the guidance of Dr. Peter Jupp at the National Institute of Virology who researched West Nile and Sindbis viruses transmitted by mosquitoes in South Africa,” Cornel recalled. “Thereafter I continued to work on mosquitoes as a scientist employed at the South African Institute for Medical Research before moving to the USA.” 

“Who would have thought that that the expertise that I gained on West Nile virus as a master student in South Africa would be used many years later after West Nile virus invaded and spread throughout the USA?”

For more than two decades, Cornel has teamed with fellow medical entomologist and “blood brother” Professor Gregory Lanzaro of the UC Davis School of Veterinary Medicine to study malaria mosquitoes in the West African country of Mali. Their work is starting to show significant results.

“Because of our commitment to conduct long term longitudinal studies and not static investigations,” Cornel said, “we have now shown that considerable selective processes are taking place causing spatiotemporal dynamics of gene flow and fitness events in major malaria vectors M (now Anopheles coluzzii)  and S (now Anopheles gambiae)  and M/S hybrids in West Africa.” 

“We are currently establishing further evidence of the important role of insecticide resistance traits in spatiotemporal dynamics of Anopheles coluzzii, Anopheles gambiae  and the Bamako form.” Cornel noted that these results have “considerably important implications in future efficacies of insecticide treated bednets to control indoor biting malaria vectors in West Africa.”

Cornel also teams with Lanzaro and Professor Heather Ferguson of the University of Glasgow to examine the ecology and associated genetics of the major malaria vector Anopheles arabiensis in Tanzania. They began working on the project four years ago.

One of his newest projects is the study of population/genetics, insecticide resistance and cytogenetics in the major malaria vector in Brazil. Cornel and Lanzaro launched their study in September when they traveled to Brazil to begin targeting the culprit, Anopheles darlingi, a “widely distributed species that has adapted to survive in multiple ecological zones and we suspect that it may consist of multiple incipient or closely related species,” Cornel said.

“While in Brazil I collected larvae and dissected salivary glands from them to examine their polytene chromosome inversion structure and polymorphisms,” Cornel related. “Inversions are vitally important to consider in genetic analyses and it takes considerable patience to interpret the chromosomes.”

Cornel and Lanzaro collaborate with Professor Paulo Pimenta of the Laboratory of Medical Entomology, René Rachou Research Centre- FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil. The UC Davis medical entomologists hope to produce good preliminary data from their research trip to write grants and establish a long-term project in Brazil.

Cornel also studies avian malaria. That interest sparked four years ago when he began working in Cameroon with scientists from UCLA and San Francisco State University (SFSU), including SFSU's Ravinger Sehgal, who studies avian blood parasites. Cornel's graduate student Jenny Carlson, in her final year of her Ph.D studies at UC Davis, is investigating avian malaria in Fresno County. 

The Cornel-Carlson research implicates that considerable fidelity exists between Culex mosquito species and species of plasmodium they transmit. “This is contrary to the currently held belief that all Culex mosquitoes are equally capable of transmitting avian malaria,” Cornel said. “In our investigations, we described a new species of avian malaria which is very common in songbirds in Fresno County (published in Parasitology Research).”

Cornel plans to continue working with Sehgal investigating the effects of deforestation on transmission of avian parasites in Cameroon. They recently submitted a National Science Foundation grant proposal. “A large swath of primary forest is slated to be deforested in Cameroon and replaced with Palm oil plantations and we will investigate the effects of this hopefully, as it happens.”

Also new on the horizon: Cornel will be starting a new mosquito-borne virus project in February. He received a Carnegie Foundation scholarly three-month fellowship to work in South Africa (February through to April). The primary objective of the project? To examine mosquito-borne viruses cycling in seven national parks in South Africa and two National Parks in Bostwana.

“It's extremely difficult to get permission to conduct field research in national parks in Southern Africa and this provides an unprecedented exciting opportunity for me to work with a friend, Professor Leo Braack from the University of Pretoria, in these parks. One has to be very careful working in some of these parks at night because of the wild predators, elephants, hippos and buffalo.”  

Cornel is active in the 30- member Center for Vectorborne Diseases (CVEC), headquartered in the UC Davis School of Veterinary Medicine and considered the most comprehensive vectorborne disease program in California. Both interdisciplinary and global, CVEC encompasses biological, medical, veterinary and social sciences.

Medical entomologist Anthony Cornel with a snake in Brazil.
Medical entomologist Anthony Cornel with a snake in Brazil.

Medical entomologist Anthony Cornel with a snake in Brazil.

UC Davis medical entomologists Anthony Cornel (foreground) and Gregory Lanzaro make annual trips to Mali to study malaria mosquitoes.
UC Davis medical entomologists Anthony Cornel (foreground) and Gregory Lanzaro make annual trips to Mali to study malaria mosquitoes.

UC Davis medical entomologists Anthony Cornel (foreground) and Gregory Lanzaro make annual trips to Mali to study malaria mosquitoes.

Posted on Tuesday, October 28, 2014 at 5:04 PM

Unraveling the Mystery of DEET

Culex quinquefasciatus filled with blood. (Photo by Kathy Keatley Garvey)
You spray DEET on your arms, and those pesky mosquitoes leave you alone.

It works.

However,  not everyone wants to use DEET, a synthetic insect repellent. There's that smell, for one thing. "Properties that people do not like in addition to the smell is that DEET is a solvent for plastic," says chemical ecoloigst Walter Leal of the University of California, Davis. "So, one gets eyeglass frames and watchbands dissolved by DEET."

There's also "the misconception that everything synthetic is bad."

So what is it with DEET that repels mosquitoes? What odorant receptor is involved? Mosquitoes, as we know, detect smells with their antennae.

The  Leal lab today (Oct. 27) published research in the Proceedings of the National Academy of Sciences (PNAS) that pinpoints the exact odorant receptor that repels them. They also identified a plant defensive compound that might mimic DEET, a discovery that could pave the way for better and more affordable insect repellents.

Walter Leal
“Mosquitoes are considered the most deadly animals on the planet, but unfortunately, not everyone who needs this repellent can afford to use it, and not all who can afford it can use it due to its undesirable properties,” said Leal, an internationally recognized professor in the Department of Molecular and Cellular Biology and co-chair of the 2016 International Congress of Entomology.

For more than six decades, DEET has been known as  the gold standard of insect repellents. More than 200 million people worldwide use the chemical insect repellent, developed by scientists at the U.S. Department of Agriculture and patented by the U.S. Army in 1946.

So when Leal and his team--project scientist Pingxi Xu, postdoctoral scholar Young-Moo Choo, and agricultural and environmental chemistry graduate student Alyssa De La Rosa-- published their groundbreaking research, “Mosquito Odorant Receptor for DEET and Methyl Jasmonate,”  they drew global attention.

In their research, they examined the receptors of the southern house mosquito, Culex quinquefasciatus, which transmits such diseases as West Nile virus.

The researchers set out to investigate two hypotheses regarding DEET's mode of action: activation of ionotropic receptor IR40a vs. odorant receptor(s). “Ionotropic receptor is another family of olfactory receptors, which seem to be the ancestral version when insects were aquatic,” Leal said. “So, the ionotropic receptors normally detect acid, bases, and other water soluble compounds.”

Anthony Cornel provided the mosquitoes.
They discovered that the direct activation of an odorant receptor, not an ionotrophic receptor, “is necessary for DEET reception and repellency in Culex mosquitoes.” They also detected a link between DEET and methyl jasmonate, thus suggesting that DEET might work by mimicking a defensive compound from plants.

“Vector-borne diseases are major health problems for travelers and populations living in endemic regions,” said Leal.  “Among the most notorious vectors are mosquitoes that unwittingly transmit the protozoan parasites causing malaria and viruses that cause infections, such as dengue, yellow fever, chikungunya, and encephalitis.”

Leal said that diseases transmitted by mosquitoes destroy more lives annually “than war, terrorism, gun violence, and other human maladies combined. Every year, malaria decimates countless lives – imagine a city of San Francisco perishing to malaria year after year. The suffering and economic consequences in endemic areas are beyond imagination for those living in malaria-free countries. Both natives and visitors to endemic areas want to keep these ‘infected needles' at bay. In the absence of vaccines for malaria, dengue, and encephalitis, one of the most ancient and effective prophylactic measures against mosquito-borne diseases is the use of DEET.”

Dan Strickman of the Bill and Melinda Gates Foundation, not involved in the study, praised the work. “We are at a very exciting time for research on insect repellents,” said Strickman, senior program officer of the Global Health Program's Vector Control. “ For decades, the field concentrated on screening compounds for activity, with little or no understanding of how chemicals interacted with mosquitoes to discourage biting. Use of modern techniques that combine molecular biology, biochemistry, and physiology has generated evidence on how mosquitoes perceive odors.”

Said zoologist Paul Weldon of the Smithsonian's Conservation Biologist Institute, also not involved in the study: “Since DEET is strictly synthetic and not a natural product, it has been challenging to understand the adaptive nature of the response it elicits. It is not as if the compound emanates from, say, spider webs or fishy water, where avoidance by mosquitoes would make sense. Xu et al. have solved the mystery of where the DEET response comes from: it is in response to plant chemical defenses.”

“This, by the way, also explains why the DEET response is widespread, occurring in many arthropods, including those that are not ectoparasitic -- like cockroaches,” Weldon said. The repellence of other arthropods by DEET may have tipped off some of those investigating the DEET response, but I'm not sure that it did. The focus of research on DEET seems to have been with the organisms in which it just so happened to be discovered -- mosquitoes. The Xu et al. study suggests that there is a much broader array of DEET-sensitive organisms than previously suspected. No doubt, this finding will assist further investigations of it.”

Professor John Pickett, Rothamsted Research, UK, also not involved in the study, called the link between the plant compound and synthetic insect repellent, DEET as a “surprising evolutionary link.”

Pickett, the Michael Elliott Distinguished Research Fellow and Scientific Leader of Chemical Ecology at Rothamsted Research and a foreign associate of the National Academy of Sciences, said: “Not only does this work demonstrate that a mosquito response to the gold standard repellent DEET, as well as the more recently developed repellents, is mediated by a specific odorant receptor (OR136 for the southern house mosquito Culex quinquefasciatus) but that the receptor responds specifically also to methyl jasmonate, involved in plant hormone-based defense against insects, which suggests a surprising evolutionary link between these types of insect interactions.”

The UC Davis researchers pointed out that “insect repellents have been used since ancient times as prophylactic agents against diseases transmitted by mosquitoes and other arthropods, including malaria, dengue fever, and encephalitis. They were developed from plant-based smoke or extracts (essential oils) into formulations with a single active ingredient.”

Progress toward development of better and more affordable repellents has been slow, they said, because scientists weren't sure which odorant receptor was involved. Now they are.

Mosquito researcher Anthony "Anton" Cornel, associate professor with the UC Davis Department of Entomology and Nematology, and based at the UC Kearney Agricultural Research and Extension Center, Parlier, provided the mosquitoes that allowed the Leal lab to duplicate his mosquito colony at UC Davis.

Look for more exciting research to come!

UC Davis scientists in the Walter Leal lab have discovered the odorant receptor in the Culex mosquito that repels DEET. From left are project scientist Pingxi Xu;  postdoctoral scholar Young-Moo Choo; AgChem graduate student Alyssa De La Rosa; and Professor Leal. (Photo credit: Academic Technology Services/Mediaworks)
UC Davis scientists in the Walter Leal lab have discovered the odorant receptor in the Culex mosquito that repels DEET. From left are project scientist Pingxi Xu; postdoctoral scholar Young-Moo Choo; AgChem graduate student Alyssa De La Rosa; and Professor Leal. (Photo credit: Academic Technology Services/Mediaworks)

UC Davis scientists in the Walter Leal lab have discovered the odorant receptor in the Culex mosquito that repels DEET. From left are project scientist Pingxi Xu; postdoctoral scholar Young-Moo Choo; AgChem graduate student Alyssa De La Rosa; and Professor Leal. (Photo credit: Academic Technology Services/Mediaworks)

Posted on Monday, October 27, 2014 at 5:05 PM

UC Davis Arboretum Plant Sale!

Tom Tucker's bee hat: all the buzz! (Photo by Kathy Keatley Garvey)
If you missed the first fall plant sale at the UC Davis Arboretum Teaching Nursery on Garrod Drive, you're in luck.

The next public sale is Saturday, Oct. 25 from 9 a.m. to 4 p.m.

We attended the sale on Saturday, Oct. 11 and it was the equivalent of Black Friday (the Friday following Thanksgiving Day). Only this was like "Green Saturday."  It was a gathering of green thumbers and wanna-be green thumbers. We delighted in seeing their enthusiasm for plants and pollinators.

Bee enthusiast/UC Master Gardener Tom Tucker of Vacaville was there to display his bee condos, or housing for leafcutting bees and blue orchard bees. The bee condos? They're easy to make, he says. His "bee hat" was all the buzz. 

Art was there in the form of ceramic insects that UC Davis Entomology 1 students created under the encouragement and direction of the UC Davis Art Science Fusion Program, co-founded and co-directed by entomologist/artist Diane Ullman and artist Donna Billick. Ullman is a professor of entomology at UC Davis and Billick is a self-described "rock artist" who retired from teaching classes at UC Davis in June--but not from art.

A ceramic ant nestled in the plant growth. (Photo by Kathy Keatley Garvey)
A sign indicated that the ceramic insects were perching, nesting or resting.

Not to be outdone by the ceramic bees, the real bees were there, too. We watched them nectar purple  lavender (Lavandula), red blanket flower (Gallardia) and the yellow bulbine (Bulbine frutescens). One good rule of thumb in purchasing plants for pollinators: observe what the pollinators like.

The UC Davis Arboretum website explains it all: "Several times each year, our support group, Friends of the UC Davis Arboretum, holds plant sales at the Arboretum Teaching Nursery, offering hundreds of different kinds of uncommon garden plants that have been locally grown, including the Arboretum All-Stars, our top recommended plants for Central Valley gardens. Dozens of volunteers work hard all year to grow plants for sale to support the Arboretum. Learn about volunteering at the Arboretum."

Check out the plant list on the website. You can download a PDF or an Excel file.

If you don't know a plant from a hole in the ground (in preparation for a plant, of course), you can ask the experts at the Arboretum Teaching Nursery.

They know.

Honey bee heading toward a bulbine (Bulbine frutesens). (Photo by Kathy Keatley Garvey)
Honey bee heading toward a bulbine (Bulbine frutesens). (Photo by Kathy Keatley Garvey)

Honey bee heading toward a bulbine (Bulbine frutesens). (Photo by Kathy Keatley Garvey)

Honey bee foraging on a blanket flower (Gallardia). (Photo by Kathy Keatley Garvey)
Honey bee foraging on a blanket flower (Gallardia). (Photo by Kathy Keatley Garvey)

Honey bee foraging on a blanket flower (Gallardia). (Photo by Kathy Keatley Garvey)

These are some of the bee condos that bee enthusiast/UC Master Gardener Tom Tucker displayed at the Oct. 11 fall sale. (Photo by Kathy Keatley Garvey)
These are some of the bee condos that bee enthusiast/UC Master Gardener Tom Tucker displayed at the Oct. 11 fall sale. (Photo by Kathy Keatley Garvey)

These are some of the bee condos that bee enthusiast/UC Master Gardener Tom Tucker displayed at the Oct. 11 fall sale. (Photo by Kathy Keatley Garvey)

Plant enthusiasts attending the Oct. 11 fall sale. (Photo by Kathy Keatley Garvey)
Plant enthusiasts attending the Oct. 11 fall sale. (Photo by Kathy Keatley Garvey)

Plant enthusiasts attending the Oct. 11 fall sale. (Photo by Kathy Keatley Garvey)

Posted on Friday, October 24, 2014 at 9:20 PM

Next 5 stories | Last story

Webmaster Email: mdhachman@ucdavis.edu