- Author: Kathy Keatley Garvey
His seminar, part of the department's weekly seminars, is from 4:10 to 5 p.m., Wednesday, Feb. 13 in 122 Briggs Hall, off Kleiber Hall Drive. The title: "Understanding the Molecular Mechanisms Underlying Photoperiodic Time Measurement in Drosophila melanogaster."
"I will talk about the molecular mechanisms involved in seasonal adaptation in insects," Brieux said. "Overwintering insects undergo profound physiological changes characterized by an arrest in development and reproduction in adults, known as diapause. While the hormonal control of reproductive diapause is relatively well described it is still unclear how organisms interpret variations in photoperiod (daylength) and temperature to modulate their physiology in order to survive through unfavorable seasons."
"In this context I will present the progress we made in the characterization of a key mechanism signaling seasonal changes in insects and how it can promote our understanding of animal seasonal timing in a comparative framework. In addition, future work on this aspect is also expected to have a broad significance in understanding the evolutionary response of pest insects to rapid climate change."
Says Brieux: "Arguably, the most well recognized seasonal response in insects is the induction of overwintering diapause, which can be induced at different life stages, and is characterized by arrest in growth and reproduction. Since PPTM is critical to seasonal adaptation in insects, it has been studied extensively. Yet, the molecular and neuronal basis of the insect photoperiodic timer has evaded characterization."
The overall goal of this study, he says, is "to address the long-standing knowledge gap using the genetically tractable Drosophila melanogaster and the migratory butterfly, the monarch, Danaus plexippus, as complementary model."
"Specifically, we propose to investigate the mechanisms by which the seasonal timer interprets and signals changes in photoperiod to elicit downstream neuroendocrine and physiological responses in insects."
D. melanogaster "continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution," according to Wikipedia. "As of 2017, eight Nobel prizes had been awarded for research using Drosophila."
Brieux received his bachelor's degree in biology in 2009 and pursued a master's degree from Pierre and Marie Curie University, Paris, France. He finished his doctorate in 2014 with faculty members Line Duportets and Christophe Gadenne at Angers University, western France, where he investigated the role of hormones and biogenic amines in the behavioral response to the sex pheromone in the noctuid Agrotis ipsilon.
The postdoctoral scientist joined the Chiu lab in the spring of 2016. In addition to his passion for research, Brieuz is a talented photographer passionate about macrophotography. Check out his photos on his website.
Associate professor Joanna Chiu, a molecular geneticist and physiologist, serves as the vice chair of the UC Davis Department of Entomology and Nematology, and is a newly selected Chancellor's Fellow. Her research expertise involves molecular genetics of animal behavior, circadian rhythm biology, and posttranslational regulation of proteins.
- Author: Kathy Keatley Garvey
Naoki Yamanaka, an assistant professor at UC Riverside (UCR), is known for his innovative and creative research. In fact, the National Institute of Health (NIH) just awarded him a $2.4 million grant in its High-Risk, High-Reward Research Program to study the role of steroid hormone transporters in insect development and reproduction. A UCR news release pointed out that he will "translate that knowledge into new ways to combat the spread of mosquitoes, which are among the deadliest animals on the plant."
Fast forward to today--actually next week! And this time, it's about fruit flies. Steroid hormone transporters in fruit flies.
Yamanaka will discuss "A Membrane Transporter Is Required for Steroid Hormone Intake in Drosophila" at the UC Davis Department of Entomology and Nematology seminar, set from 4:10 to 5 p.m., Wednesday, Oct. 24, in 122 Briggs Hall. Host is seminar coordinator and medical entomologist Geoffrey Attardo, assistant professor of entomology.
"Steroid hormones are a group of lipophilic hormones that are believed to enter cells by simple diffusion to regulate diverse physiological processes through intracellular nuclear receptors," Yamanaka explains. "We recently challenged this model in the fruit fly Drosophila melanogaster by demonstrating that a membrane transporter that we named Ecdysone importer (Ecl) is involved in cellular uptake of the steroid hormone ecdysone.Eci encodes an organic anion transporting polypeptide of the evolutionary conserved solute carrier organic anion superfamily. Results of our study may have wide implications for basic and medical aspects of steroid hormone research."
Yamanaka, who received his doctorate in biological sciences in 2007 from the University of Tokyo, says that his lab is "focused on identifying and characterizing neuroendocrine signaling pathways that regulate physiological and behavioral changes during insect development. Similar to humans, where physical and mental development during juvenile stage (puberty) is controlled by the neuroendocrine system, insects also have a sophisticated hormone signaling network that regulates their developmental transitions. Mainly by using fruit fly molecular genetic tools, we would like to understand what kind of hormones and receptors are involved in this system, how they work at the molecular level, and how such knowledge can be applied to develop new approaches to control animal development."
This is exciting research.
What exactly are "steroid hormones?" As author Sarah Nightingale explained in the UCR news release:
"Steroid hormones mediate many biological processes, including growth and development in insects, and sexual maturation, immunity and cancer progression in humans. After they are produced by glands of the endocrine system, steroid hormones must enter cells to exert their biological effects. For decades, the assumption has been that these hormones enter cells by simple diffusion, but preliminary work in Yamanaka's lab suggests a defined passageway controlled by proteins called membrane transporters."
Said Yamanaka: "The overall goal of this project is to challenge the conventional paradigm in endocrinology that steroid hormones freely travel across cell membranes by simple diffusion. We will also screen chemicals that inhibit steroid hormone entry into cells, with the goal of developing new pest control reagents.”
The NIH High-Risk, High-Reward Research Program is quite competitive. This year NIH officials granted only 89 awards and they were to “extraordinarily creative scientists proposing highly innovative research to address major challenges in biomedical research.”
Yamanaka's research may lead to important pest control strategies for mosquitoes that transmit deadly diseases. As Nightingale explained: "Using the simple but powerful fruit fly model, his team will study how the insect steroid hormone ecdysone is transported in (and potentially out) of cells with the help of membrane transporters. Since ecdysone controls metamorphosis and molting as an insect moves from one stage of its life cycle to the next, blocking its transport could offer a new way to inhibit insect growth and development. The team will then study the same transport pathway in the mosquito that causes yellow fever, hoping to identify chemicals that inhibit steroid hormone transport as a pest control strategy. Worldwide, mosquito-borne diseases cause millions of deaths each year, with malaria alone causing more than 400,000 deaths, according to the World Health Organization."
Bottom line: “By targeting the membrane transporter from outside the cells, we may be able to circumvent common pesticide resistance machinery provided by proteins within the cells, such as detoxification enzymes and drug efflux pumps,” Yamanaka pointed out in the news release.
His seminar at UC Davis is the fifth in a series of fall seminars coordinated by Attardo. (Note: The Yamanaka seminar will not be recorded.)
Upcoming seminars include:
4:10 p.m., Wednesday, Oct. 31
Fred Wolf, assistant professor, UC Merced: (tentative title) "Drunken Drosophila and the Coding of Brain Plasticity"
Host: Joanna Chiu, associate professor and vice chair, UC Davis Department of Entomology and Nematology
4:10 p.m., Wednesday, Nov. 7
Lark Coffey, assistant professor in the Department of Pathology, Microbiology and Immunology, UC Davis School of Veterinary Medicine: "Zika Virus in Macaques, Mice and Mosquitoes: Contrasting Virulence and Transmissibility in Disparate Hosts"
Host: Geoffrey Attardo
- Author: Kathy Keatley Garvey
The Mediterranean fruit fly, considered the world's worst agricultural pest, is one of at least five fruit flies established in California. It cannot be eradicated.
So says entomologist James Carey of the UC Davis Department of Entomology and Nematology, who has been dogging medflies since his faculty appointment in 1980. (See what drove him.)
Carey and UC Davis-affiliated colleagues Nikos Papadopoulos and Richard Plant wrote the eye-opening research piece, "From Trickle to Flood: The Large Scale, Cryptic Invasion of California by Tropical Fruit Flies" in the current edition of the renowned Proceedings of the Royal Society B.
Their work "clearly demonstrates that at least five and as many as nine species of tropical fruit flies, including the infamous Medfly, are permanently established in California and inexorably spreading, despite more than 30 years of intervention and nearly 300 state-sponsored eradication programs aimed at the flies," wrote Pat Bailey in a UC Davis News Service story released today.
The findings, Bailey pointed out, have "significant implications for how government agencies develop policies to successfully manage pests that pose a threat to California's $43.5 billion agricultural industry."
Carey, an international authority on fruit-fly invasion biology, told her that "Despite due diligence, quick responses, and massive expenditures to prevent entry and establishment of these insects, virtually all of the fruit-fly species targeted by eradication projects have been reappearing in the same locations — several of them annually — and gradually spreading in the state."
Carey, Papadopoulos and Plant detailed the problem in the opening paragraph of their meticulously researched paper: "Since 1954 when the first tropical tephritid fruitfly was detected in California, a total of 17 species in four genera and 11,386 individuals (adults/larvae) have been detected in the state at more than 3348 locations in 330 cities." That's three out of four California cities.
Michael Parrella, professor and chair of the UC Davis Department of Entomology and Nematology: "The study has dramatic implications for California agriculture and the state’s international trading partners, and speaks to the urgent need to alter current eradication policies aimed at invasive species."
Frank Zalom, UC Davis entomology professor and incoming president of the 6500-member Entomological Society of America: “This study deserves serious consideration, and I hope that it helps lead to new discussions on a long-term approach for dealing with fruit flies and similar exotic pests by the United States and international regulatory authorities."
Former UC Davis chancellor Ted Hullar (1987-1994), one of the first to believe in "the science" that Carey presented, said: “From our first conversation, Jim struck me as a serious-minded guy, with strong ideas and clear focus, pursuing his insights and beliefs no matter the struggle. Good science and progress comes from that, making new paths in tough terrain, believing in the power of journey, as well as goal.”
The Medfly prefers such thin-skinned hosts as peach, nectarine, apricot, avocado, grapefruit, orange, and cherry. The female may lay one to 10 eggs per fruit or as many as 22 eggs per day. She may lay up to 800 eggs during her lifetime, but usually about 300.
We remember when the Medfly wreaked economic havoc in the Solano County city of Dixon in September 2007. We were there.
At the time, Carey told us that "this may be just one of many isolated pockets of medfly infestations in California. This is really serious because the invasion process is so insidious."
The Medfly has been multiplying and spreading undetected--like cancer--for years, he said. "It may be a symptom of a much larger problem. But any way you look at it, this is the first really big outbreak in the Central Valley."
CDFA set up a command center at the Dixon May Fair and imposed a 114-mile radius quarantine of fruits, vegetables and nuts. Dixon was deep in the throes of tomato and walnut harvesting. The owner of a 65-acre organic produce farm that ships to 800 clients worried that he might lose $10,000 a week in potential sales.
Among the actions that the California Department of Food and Agriculture (CDFA) took at the onset:
- Stripped all fruit from trees within a 100-meter radius of all Medfly finds
- Ground-sprayed the organic compound Naturalyte (the active ingredient is Spinosad, a naturally occurring product of a soil bacteria) within a 200-meter radius of all Medfly finds
- Set 1,700 fruit fly traps within an 81-square mile grid in all of Dixon and the surrounding area from near the Yolo County border to Midway Road
- Began aerially releasing 1.5 million sterile male medflies (dyed pink for easy detection) over a 12-square mile area on Sept. 14, with weekly releases of 3 million medflies scheduled for at least nine months
- Set up a yearlong command center, with four portable buildings and a task force of 25, on the Dixon May Fair grounds
Fast forward to today. Now that the Medfly has been declared a "permanent resident," what's next?
Carey agrees that “CDFA needs to continue to respond to outbreaks as they occur, but he advocates long-term planning based on “the science” that the insects are established. This includes heightened monitoring levels for the agriculturally rich Central Valley, an economic impact study, risk management/crop insurance, cropping strategies, fly fee zones/post harvest treatments, emergency/crisis planning, genetic analysis and a National Fruit Fly Program.
“Inasmuch as the Mediterranean, Mexican, Oriental, melon, guava and peach fruit flies have all been detected in the Central Valley, monitoring this incredibly important agricultural region should be increased by 5 to 10-fold in order to intervene and suppress populations and thus slow the spread,” Carey says.
“These pests cannot be wished away or legislated out of existence. Policymakers need to come to grips with this sobering reality of multiple species permanently established in our state in order to come up with a long-term, science-based policy for protecting agriculture in our state.”
(See James Carey's website for links to his work on fruit fly invasion.)
- Author: Kathy Keatley Garvey
If you're suffering from a sleep disorder, then you'll want to know the kind of research that molecular geneticist Joanna Chiu of the UC Davis Department of Entomology is doing--with fruit flies.
The research may one day lead to alleviating your sleep disorder.
Chiu and two of her former colleagues at Rutgers just published groundbreaking research in the journal Cell. They identified a new mechanism that slows down or speeds up the internal clock of fruit flies.
By mutating one amino acid in a single protein, "we changed the speed of the internal clock and flies now ‘think' it is 16 hours a day instead of 24 hours a day," said Chiu, an assistant professor of entomology.
"Our goal, of course, is not to trick flies into thinking the day is shorter or longer, but to dissect this complex phospho-circuit (phosphorylation sites) that controls clock speed in metazoans."
Their work, involving the fruit fly, Drosophila melanogaster, was funded by the National Institutes of Health.
The world of circadian clocks is a complex one. "Living organisms-plants, animals and even bacteria-have an internal clock or timer that helps them to determine the time of day," Chiu said. "This internal clock is vital to their survival since it allows them to synchronize their activity to the natural environment, so that they can perform necessary tasks at biologically advantageous times of day."
"A functional clock is required to generate proper circadian rhythms of physiology and behavior including the sleep-wake cycle, daily hormonal variations and mating rhythms," Chiu said.
Read more about her research on the UC Davis Department of Entomology website.
The fruit fly, small in size--about 1/8th inch long--stands tall as a prized tool for genetic research and developmental studies.
Indeed, the red-eyed fly is a "golden bug.”
- Author: Kathy Keatley Garvey
Roger Vargas is in the thick of fruit-fly research and he probably wishes those insects would thin out.
He's a research entomologist at the USDA-ARS Pacific Basin Agricultural Research Center in Hilo, Hawaii. For those who don't deal with acronyms, that's the Agricultural Research Service of the U.S. Department of Agriculture.
Vargas' key research interests include mass rearing, sterile insect technique, ecology, biological control, and area-wide integrated pest management (IPM) of fruit flies.
Vargas will be at the University of California, Davis, on Wednesday, Feb. 9 to speak on "Area-Wide Fruit Fly Programs against Fruit Flies in Hawaii, French Polynesia and California." His talk, sponsored by the UC Davis Department of Entomology and part of its winter seminar series, is set from 12:10 to 1 p.m. in 1022 Life Sciences Addition, corner of Hutchison and Kleiber Hall drives.
The lecture will be webcast live at http://uc-d.na4.acrobat.com/ucsn1/ and then archived here. He plans to cover current area-wide management programs against Bactrocera fruit flies in Hawaii, French Polynesia, and California.
"Fruit flies (Diptera: Tephritidae) are among the most economically important pests attacking soft fruits worldwide," Vargas says. "Bactrocera is a tephritid fly genus of at least 440 species distributed primarily in tropical Asia, the south Pacific, and Australia. However, these species have been spreading throughout the world at an alarming rate over the past 15 years.
"Oriental fruit fly (B. dorsalis) has become established and is spreading throughout French Polynesia.
"Carambola fruit fly (B. carambolae) is established and spreading throughout areas of South America.
"B. invadens, B. latifrons and melon fly (B. cucurbitae) are established and spreading in Africa.
"The peach fruit fly (B. zonata) is established and spreading in Africa and the Mediterranean region."
In fact, Vargas says, every year Bactrocera species are accidentally introduced from various parts of the world into California, requiring expensive treatment programs.
For an up-close and personal look at a fruit fly, check out the USDA-ARS photo of a Oriental fruit fly laying eggs in a papaya (below).
Coming soon...to a fruit near you...
