Hillary Thomas' biological control research on a leaf-eating beetle that targets saltcedar has scored a bullseye.

Thomas, a doctoral candidate in entomology at UC Davis, has received a $15,000 Robert and Peggy van den Bosch Memorial Scholarship to support her research.

Saltcedar or tamarix (Tamarix spp.) is a major pest that threatens waterways. In the western United States alone, the plant impacts several million acres of prime riparian land. 

Thomas researches Diorhabda elongata, a saltcedar leaf beetle native to Central Asia and  a natural enemy of the pest.

She won the award for her project, “Impact of Host-Plant Preferences on Establishment and Efficacy of Diorhabda elongata (Coleoptera: Chrysomelidae), a Biological Control Agent of Saltcedars.” She studies with major professor Frank Zalom, an integrated pest management specialist.

“Hillary is an outstanding young scientist who is committed to the implementation of biological control,” said Zalom. “Her dissertation research on host plant acceptance by the beetles introduced for control of invasive saltcedar is not only useful for that system but will lead to better understanding of the importance of post-release evolution in biological control agent establishment.  She is highly motivated."

 "The beetle has shown great potential to control the weed in some release areas," said Thomas, who collaborates with the Exotic and Invasive Weeds Unit of the U.S. Department of Agriculture/Agricultural Research  Service.  "It causes defoliation to the extent that it appears there will be a population-level effect on tamarix stands.”

Thomas' work initially focused on improving insect establishment success in the Cache Creek watershed, near Rumsey, Yolo County, where Tamarix parviflora grows.  Today she compares the host plant preferences of two populations: the field population beetles and a  source lab colony.

“It seems there might be an increase in host plant acceptability of Tamarix parviflora by the field population,” Thomas said. “I am repeating both field and laboratory experiments at the moment to determine whether there is substantial evidence to support this.”

Saltcedar, first imported to the United States from the Middle East in the 1880s for erosion control and as an ornamental, is extremely aggressive and invasive. As a shrub or small tree, it forms dense thickets, displacing native plants and animals. Its long tap roots suck in massive amounts of water.  It also drops its salt-infused foliage on the surface, inhibiting other plant growth.

A single saltcedar can produce as many as 600,000 seeds annually, according to weed specialist Joseph DiTomaso of the UC Davis Department of Plant Sciences. Chemical, mechanical and cultural control techniques are effective, but expensive and temporary.  

Three other UC Davis doctoral candidates shared in the Robert and Peggy van den Bosch scholarships.

Amanda Hodson, who studies with major professor Edwin Lewis (he holds a joint appointment in  nematology and entomology) received $10,000 to continue her research on “Ecological Influence of Entomopathogenic Nematodes in Pistachio Orchards.”

Yao Hua Law, of entomologist Jay Rosenheim's lab, received $5000 to support his work on "Multiple Predators Improve Biocontrol: Niche Complementarity and Cannibalism.” He also received a $1115 van den Bosch travel award to attend the Ecological Society of America annual meeting in Milwaukee, Wisc., to present his work on predation.

 Andrew Sutherland, of entomologist Michael Parrella's lab, received a $1500 van den Bosch travel award for his “Manual Transmission of Powdery Mildew Fungi Mediated by Activity of an Obligate Mycophagous Beetle (Coleoptera: Coccinellidae).” He will attend the Brazilian Society of Entomology conference, set Aug. 24-29. .

The van den Bosch scholarship program provides a total of $60,000 to $80,000 annually  for work related to biological control,  said coordinators Kent Daane and Nicholas Mills,  co-directors of the Center for Biological Control, UC Berkeley. Eligible to apply are doctoral candidates from UC Davis, UC Berkeley and UC Riverside. Typically, the winners receive $15,000, $10,000 or $5,000. Selection is by a panel of biocontrol faculty representing the three schools. 

In addition, Daane and Mills annually present  travel awards totalling $15,000 to $20,000. The maximum amount is $1500 per student.

Others receiving scholarships were UC Berkeley students Rebecca Chaplin-Kramer (major professor: Claire Kremen, also a UC Davis Department of Entomology affiliate), Mel Stravrinides (major professor:  Nicholas Mills); and Eleanor Blitzer (major professor:  Stephen Welter). Receiving travel funds: Mel Stravrinides and Eleanor Blitzer, UC Berkeley; and Jason Mottern and Jennifer Henke, UC Riverside. 

Robert van den Bosch (1922-1978) served as a researcher, teacher, and an administrator in the Division of Biological Control and the Department of Entomological Sciences, UC Berkeley, from 1963 until his death. A native of Martinez, Calif., he was a lifelong advocate of  biological control.  His colleagues said he searched tirelessly for natural enemies of agricultural pests, an effort that resulted in the importation and establishment of 17 natural enemy species.

With the recent death of his wife, Peggy, more funds (at her request) were added to the van den Bosch awards program.

If she were boarding an airline, she'd be charged double for baggage.

But she didn't and she wasn't.

She's a pollen-packed sunflower bee enjoying our sunflower. Not a honey bee but a sunflower bee.  A native bee.

A Svastra obliqua expurgata (Cockerell), as UC Davis native pollinator researcher RobbinThorp said.

“ I have seen them nesting in gardens in Davis--including at one of the dorms on campus--and nesting in a dirt roadway on Joyce Island (Solano County),” said Thorp, emeritus professor of entomology at UC Davis.  He's also seen the sunflower bees visiting native plants in a Sacramento cemetery.

“The males,” Thorp said, “spend much time cruising searching for females.  The males  have long antennae and thus are called ‘long-horn' bees.  The males also have greenish eyes, and bright yellow markings on the lower face.” 

 Both males and females are larger than honey bees and fly more rapidly when foraging, Thorp said.  “They are among the native bees that interact with honey bees on the male rows of hybrid sunflower fields, disturbing the honey bees and causing them to fly out of the male rows into the female rows, thus increasing the pollination efficiency of honey bees as shown in the research by Sarah Greenleaf and Claire Kremen.”

Kremen, an affiliate of the UC Davis Department of Entomology and a regular at the Harry H. Laidlaw Jr. Honey Bee Research Facility on the UC Davis campus, is a conservation biologist at UC Berkeley and the recipient of a MacArthur genius fellowship.

Thorp said Svastra females have dense brushes of hairs on their hind legs and transport pollen dry in these brushes (scopae). Honey bees carry pollen moist on concave hair-fringed pollen baskets (corbiculae).

I wonder what writer Gertrude Stein (1874-1946), known for such prose as “a rose is a rose is a rose” and “there is no there there,” would have said about bees.

Perhaps “a bee is a bee is a bee?” 

Or “a sunflower is a sunflower is a sunflower?”

It isn't and it isn't.

We know it works, but how?

Just how does DEET work? Does it jam the senses of a mosquito? Does it mask the smell  of the host?

You spray the chemical repellent on your arm and thankfully, those darn skeeters leave you alone.  They need a blood meal to develop their eggs, so off they buzz to find another host, one that's not so inhospitable.

But why do mosquitoes avoid DEET?

Well, they avoid it because it smells bad to them. Yes, they can smell it--that's why they avoid it.

The groundbreaking research, the work of UC Davis chemical ecologist Walter Leal and researcher Zain Syed, is published today in the Proceedings of the National Academy of Sciences (PNAS), which lifted the news embargo at 2 p.m., Pacific Standard Time.

The research contradicts a Science article published in March by researchers at Rockefeller University, New York. The researchers, as other scientists have long believed, said mosquitoes can't smell DEET because it jams the odorant receptors in insect nervous systems.

The Leal-Syed research solidly establishes the real mode of action.

Noted entomologist James "Jim" Miller of Michigan State University praised the Leal-Syed work as correcting “long-standing erroneous dogma.”

Said Miller: "For decades we were told that DEET warded off mosquito bites because it blocked insect response to lactic acid from the host -- the key stimulus for blood-feeding. Dr. Leal and co-workers escaped the key stimulus over-simplification to show that mosquito responses -- like our own -- result from a balancing of various positive and negative factors, all impinging on a tiny brain more capable than most people think of sophisticated decision-making.”

“This new work corrects long-standing erroneous dogma, and shows that recent work on DEET mode-of-action published in the flagship journal, Science, apparently was flat-out wrong,” Miller said. “One of the great attributes of science is that, over time, it is self-correcting."

Leal, past president of the International Society of Chemical Ecology  and former chair of the UC Davis Department of Entomology, said previous findings of other scientists showed a “false positive” resulting from the experimental design. 

Now that we know that skeeters can smell it, this will no doubt lead to better methods of insect control. Or, as Major Dhillon, president of the American Mosquito Control Association and district manager of the Northwest Mosquito and Vector Control District, Riverside, said: ”In the future, this new knowledge can be incorporated into developing new repellents and may be in control strategies for Culex quinquefasciatus and other mosquitoes.”

Those darn female mosquitoes, always in a “Let-us-prey” mood, have clearly met their match: the "why" behind "Let us spray."

“The war is over—again,” wrote reporter Pat Brennan of the Orange County Register in a news article published Aug. 14.

Brennan was referring to the war against the Mediterranean fruit fly, a tiny pest that targets some 260 crops. The pest, first detected inCaliforniain 1975, prefers such hosts as peach, nectarine, apricot, avocado, grapefruit, orange and cherry. It is considered the world's worst agricultural pest.

California State Department of Agriculture had earlier announced the eradication of the medfly in three counties:Los Angeles, Solano andSanta Clara.If it were to become permanently established in California, the medflycould cost the state  $1.3 to $1.8 billion in annual losses,  estimated CDFA Secretary A. G. Kawamura.

I remember whenSolanoCountyag officials discovered four live medflies in a single trap in downtownDixon. The date:  Monday, Sept. 10, 2007. Newspapers bannered the story. A quarantine ensued.   Farmers fretted, and rightfully so.  Later I attended a press conference at theNutTreeAirport, Vacaville;a pilot had just released the first of many millions of sterile male fruit flies over Dixon. He showed us the  sterile medflies, dyed pink.

The sterile flies mate with wild flies and biologically force wild populations out of existence, the CDFA says.

UC Davis entomologist James Carey, who has published widely on the medfly, said the pest has been multiplying and spreading undetected--like cancer--for years in California.  He says it's never been really eliminated and he questions whether it could ever be eradicated.

CDFA and Solano County ag officials said no; that an errant tourist likely brought it to Dixon on a piece of fruit fromHawaii. The medfly lays its eggs inside fruit.

Medfly wars ensued.

Carey shared an email he sent Aug .14 to Brennan:

“The absence of medfly appearances anywhere else in the continental U.S. besides California over the past two decades strongly supports the argument that the medfly has never been completely eradicated in our state. CDFA's efforts at eradication have been successful at driving the populations back to subdetection levels for a few years. However, the reappearances of the medfly in the same cities and even in the same locations within these cities is due to a long-term established population.  Although I fully acknowledge the need to respond to the medfly when it appears in the state as it did last year, I have no reason to believe that this program will have been any more successful than the previous ones which merely suppressed rather than eliminated the medfly population from the state."

“This recent declaration of eradication is around the 50th emergency response to medfly outbreaks over the past two decades by CDFA, virtually all of which have been in the same general locations. To my knowledge during this same period no other state such as Arizona, Florida or Texas has experienced any outbreaks even though these states, like California, have climates suitable for the medfly establishment and have many tourists and migrants who are capable of introducing the medfly. These states have experienced no outbreaks while California has experienced 50.”

The CDFA Web site says medflies are not established in California. 

"These (medflies) and other exotic pests have not become established in California due to (1) strict federal exterior and state interior quarantines, (2) a pest detection program, and (3) aggressive eradication programs when an infestation is discovered."

Carey, who has plotted all medfly finds in California, says medfly populations  “do not really get going until late summer and fall. Stay tuned for this fall.”

One thing is certain: the little bugger draws a lot of attention. That's because, as Brennan wrote, it “attacks so many crops.”