Newly published research led by UC Davis distinguished professor Walter Leal and  Jiao Yin of the Chinese Academy of Agricultural Sciences, Beijing, identifies the major sex pheromone receptor gene involved in the unusual 48-hour rhythm clock of the large black chafer beetle, a severe agricultural pest that targets such crops as peanuts, potatoes and soybeans in China, Japan, South Korea and India. 

The research, “Circabidian Rhythm of Sex Pheromone Reception in a Scarab Beetle,” published in the Jan. 18 edition of Current Biology, marks the first sex pheromone receptor identified in Coleoptera, the order of beetles. 

While most insects exhibit a 24-hour circadian rhythm that regulates their behavior and physiology, the large black chafer beetle, Holotrichia parallela, operates on a 48-hour clock, said Leal, a global expert on insect olfaction and communication.  A professor in the Department of Molecular and Cellular Biology, he is a former professor and chair of the UC Davis Department of Entomology, now the Department of Entomology and Nematology. 

“Insects smell with their antennae,” said Leal, who has unraveled the molecular mechanisms of mosquitoes, true bugs, long horned beetles, moths and other insects. “They have a sophisticated olfactory system and can selectively detect minute amounts of odorants.” 

The female H. parallela emerges from the soil every other night, after sunset, climbs the canopy of the host plant, and seeks a mate by releasing a sex pheromone. Leal wanted to know if the males are also on a 48-hour rhythm clock, and he wanted to identify the elusive male gene in the pheromone receptor that allows the male to scent the female's pheromone.

The answers: “yes” and “yes.” 

“I have been waiting for almost three decades to answer these questions,” Leal said. “I identified the sex pheromone of this beetle species in 1993 while working for the Ministry of Agriculture and Forestry of Japan. At that time, I found for the first time a very unusual sex pheromone, which is derived from an amino acid. Now similar sex pheromones have been identified from many species of beetles.” 

“Also, we showed that females produce the sex pheromone every other night,” Leal said. “The burning question in biology is what males do about sensing or smelling the female sex pheromone. Back then, we had no idea how insects sense smell. With the advancements in sequencing, we identified all potential receptors and identified which one senses the sex pheromone. COVID happened and delayed our research collaboration. Finally, we found that the receptor is expressed every other day.”

“This is remarkable,” Leal said. “How do they know when it is a 'date night' or a non-calling night? It is still a mystery, but we will find out one day.”  

Leal and Yin and their team pointed out that virtually all life on Earth experiences a 24-hour circadian rhythm, which affects almost all behaviors, including sexual activity and mating. 

“I love science that leverages rigorous molecular and cellular analysis to tell stories about fascinating natural history of species,” shared molecular geneticist and physiologist Joanna Chiu, chair of the UC Davis Department of Entomology and Nematology, in an email to the UC Davis News and Media Relations and the Department of Entomology and Nematology. “This study fits the bill. When Professor Leal first told me about the circabidian rhythm of pheromone release and reception in this scarab beetle, I was more than intrigued. Circadian rhythms (24-hour rhythms) in physiology and behavior are commonly observed in organisms, from bacteria to humans, but observations of circabidian rhythms (48-hour rhythms) in nature are rare. This elegant study by Professor Leal and his collaborators has provided us with an in-depth description of how the circabidian rhythm of pheromone detection in this beetle is generated. But like all good science, this study has now generated many more interesting questions that need to be answered.” 

Leal, a native of Brazil, received his Ph.D. in applied biochemistry from the University of Tsukuba, Japan, with subsequent postdoctoral training in entomology and chemical ecology at the National Institute of Sericultural and Entomological Science and Cornell University, respectively. He was the first non-Japanese person to earn tenure at Japan's Ministry of Agriculture, Forestry, and Fisheries. 

Leal, who joined the UC Davis faculty in 2000, is a newly elected trustee of the Royal Entomological Society, the first UC Davis scientist to be elected a trustee. He chaired the UC Davis Department of Entomology in 2006-2008 before accepting a position in 2008 as professor of biochemistry in the Department of Molecular and Cellular Biology.  His many honors include Fellow of the Entomological Society of America (2009), American Association for the Advancement of Science (2005), and the National Academy of Inventors (2019). 

Other co-authors of the Current Biology paper:  Yinliang Wang, Huanhuan Dong, Yafei Qu, Jianhui Qin, Kebin Li, Yazhong Cao and Shuai Zhang, Chinese Academy of Agricultural Sciences, Beijing; Yuxin Zhou and Bingzhong Ren, Northeast Normal University, Changchun, China; and Chen Luo, Beijing Academy of Agriculture and Forestry Sciences. 

The research drew financial support from the National Key R&D Foundation of China; National Natural Science Foundation, China; and the Natural Science Foundation of Beijing. 

Resources:

• For This Beetle, ‘Date Night' Comes Every Other Day, Jan. 18, 2024, Andy Fell, UC Davis News and Media Relations
• Walter Leal Elected Trustee of Royal Entomological Society, Sept. 5, 2023

Newly selected department chair Joanna Chiu welcomed faculty, graduate students and staff at the UC Davis Department of Entomology and Nematology's fall social, held recently in the Putah Creek Lodge.

The fall social, billed as "a place to unwind and indulge," featured a light buffet and beverages.

Professor Chui, a molecular geneticist-physiologist and the outgoing vice chair, is serving a five-year term as chair, effective July 1, 2023.  She succeeds nematologist and professor Steve Nadler, who had chaired the department  since Jan. 1, 2016. 

Chiu thanked Nadler for his exceptional service. "Steve has been an exceptional leader for our department through some very challenging times. He has been fair-minded, compassionate, and has led the department with poise and a clear vision.  He has been a great mentor for me personally, and I am positive that the many lessons I have learned from him will come in very handy as I serve as chair. I am very grateful for all the support from the faculty, staff, and students in the department, and most of all, to faculty colleagues who have been stepping up to serve on key positions in department and graduate group committees during this transition. I cannot thank them enough."

Said Nadler: "I'm very pleased that we have a new group of leaders guiding the department as we move forward. I'm confident that Joanna (Chui), Rachel (Vannette) and Louie (Yang) will respond to whatever challenges are ahead."

Rachel Vannette, vice chair of the Department of Entomology and Nematology.

Community ecologist and associate professor Rachel Vannette, currently on sabbatical, is the newly selected vice chair of the department, and community ecologist and professor Louie Yang, is the Entomology Graduate Program chair, replacing Chiu.

The department is ranked as one of the top entomology departments in the United States. In November 2007, the Chronicle of Higher Education ranked it No. 1 in the country. (See news story)

Chiu joined the Department of Entomology and Nematology in 2010 as an assistant professor, and advanced to associate professor and vice chair in 2016, and to professor and vice chair in 2021. She was named one of 10 UC Davis Chancellor's Fellows in 2019, a five-year honor awarded to associate professors who excel in research and teaching. The UC Davis Academic Senate honored her with a Distinguished Teaching Award, Graduate/Professional category, in 2022. She most recently received the Chancellor's Award for Excellence in Mentoring Undergraduate Research.

Chiu co-founded and co-directs (with professors Jay Rosenheim and Louie Yang) the campuswide Research Scholars Program in Insect Biology, launched in 2011 to provide undergraduates with a closely mentored research experience in biology. The program's goal is to provide academically strong and highly motivated undergraduates with a multi-year research experience that cultivates skills that will prepare them for a career in biological research.

Nadler began his five-year term as chair on Jan. 1, 2016, succeeding Michael Parrella, who accepted a position as the dean of the College of Agricultural and Life Sciences, University of Idaho, effective Feb. 1, 2016. 

Nadler joined the UC Davis faculty in 1996 as an associate professor and associate nematologist, advancing to professor in 2001. He was named chair of the Department of Nematology in May 2005 and held that leadership position until June 2011. Active in the American Society of Parasitologists, Nadler served as the organization's president from 2007 to 2008. (See news story)

The two departments merged in 2011, but the department was not officially renamed the Department of Entomology and Nematology, until May 28, 2013.  The department today has some 25 faculty.

The UC Davis Department of Entomology began as an offshoot of the Department of Entomology and Parasitology at UC Berkeley and the two were closely entwined for more than 50 years before the UC Davis Department of Entomology became autonomous on July 1, 1963. 

UC Davis offered a two-year non-degree program in entomology, beginning in 1913. The first degree in entomology provided at UC Davis was in 1923-24 at which time Stanley B. Freeborn (for whom Freeborn Hall is named) was transferred from UC Berkeley to UC Davis to head the program.

Resources: History

• UC Davis Department of Entomology
• UC Davis Department of Nematology 

Molecular geneticist-physiologist Joanna Chiu, professor and vice chair of the UC Davis Department of Entomology and Nematology, is the newly appointed chair of the department, serving a five-year term effective July 1, 2023. She succeeds Steve Nadler, the department chair since Jan. 1, 2016. 

"I am pleased Joanna Chiu has been appointed as the chair of the Department of Entomology and Nematology," said Helene Dillard, dean of the UC Davis College of Agricultural and Environmental Sciences. "She is an outstanding scholar and teacher with demonstrated leadership skills.  I look forward to watching Professor Chiu thrive in her new role as chair and seeing the department continue to flourish.”

The new vice chair is community ecologist and associate professor Rachel Vannette, and the new Entomology Graduate Program chair, replacing Chiu, is community ecologist and professor Louie Yang. 

Other women scientists who have chaired the department:  Professor Diane Ullman, 2004-05, and interim chair, Lynn Kimsey, 2008-09.

Chiu joined the Department of Entomology and Nematology in 2010 as an assistant professor, and advanced to associate professor and vice chair in 2016, and to professor and vice chair in 2021. She was named one of 10 UC Davis Chancellor's Fellows in 2019, a five-year honor awarded to associate professors who excel in research and teaching. The UC Davis Academic Senate honored her with a Distinguished Teaching Award, Graduate/Professional category, in 2022. She most recently received the Chancellor's Award for Excellence in Mentoring Undergraduate Research.

Chiu co-founded and co-directs (with professors Jay Rosenheim and Louie Yang) the campuswide Research Scholars Program in Insect Biology, launched in 2011 to provide undergraduates with a closely mentored research experience in biology. The program's goal is to provide academically strong and highly motivated undergraduates with a multi-year research experience that cultivates skills that will prepare them for a career in biological research.

A native of Hong Kong and a first-generation college student, Joanna received her bachelor's degree, magna cum laude, in biology and music from Mount Holyoke College, Mass., and her doctorate in molecular genetics in 2004 from New York University, New York. She trained as a postdoctoral fellow from 2004 to 2010 in molecular chronobiology at the Center for Advanced Biotechnology and Medicine, at Rutgers, the State University of New Jersey.  Her postdoctoral training was funded by an NIH F32 Ruth L. Kirschstein National Research Service Award postdoctoral fellowship and K99/R00 Pathway to Independence Award.

"I grew up not knowing any scientists,” she related. “Both my parents work in the financial industry and neither went to college. However, my dad loves the outdoors and my childhood memories includes snorkeling with my dad and siblings, hiking in the very limited outdoors in my native Hong Kong, and watching a lot of National Geographic on TV. As a result, I have always been curious about biology, especially animal behavior.  I really hoped to study biology in college. My parents, on the other hand, wanted me to be a doctor."

“I certainly have never ever dreamed of being a professor when I was a college student. I just know I love biological research so I can learn more about the natural world, I love asking questions, and I love the joy of discovery."

Vannette joined the UC Davis Department of Entomology and Nematology in 2015 after serving as a postdoctoral fellow at Stanford University's biology department. As a Gordon and Betty Moore Foundation Postdoctoral Fellow from 2011 to 2015, she examined the role of nectar chemistry in community assembly of yeasts and plant-pollinator interactions.

A native of Hudsonville, Mich., Vannette received her doctorate in ecology and evolutionary biology from the University of Michigan, in 2011. She was selected a UC Davis Hellman Fellow in 2018 and a Chancellor's Fellow, a five-year honor, in 2023.

Yang, a native of Australia, but who grew up in West Virginia, received his bachelor's degree in biology from Cornell University, magna cum laude, in 1999, and a doctorate in population biology from UC Davis in 2006. He received the University of California President's Postdoctoral Fellowship to train with Professor Jonathan Levine (UCSB) and Professor Mary Power (UCB). He joined the UC Davis Department of Entomology and Nematology as an assistant professor in 2008, advanced to associate professor in June 2015, and to professor in July 2021. Yang is highly regarded for his research and mentoring. He received the 2017 Eleanor and Harry Walker Academic Advising Award, the 2018 NACADA international Outstanding Faculty Academic Advising Award, and the 2023 Distinction in Student Mentoring Award from the Pacific Branch, Entomological Society of America.

The Department of Entomology at UC Davis began as an offshoot of the Department of Entomology and Parasitology at UC Berkeley and the two were closely entwined for more than 50 years before the UC Davis Department of Entomology became autonomous on July 1, 1963. The department now has 24 faculty, plus a lecturer. 

UC Davis offered a two-year non-degree program in entomology, beginning in 1913. The first degree in entomology provided at UC Davis was in 1923-24 at which time Stanley B. Freeborn (for whom Freeborn hall was named) was transferred from UC Berkeley to UC Davis to head the program. (See https://entomology.ucdavis.edu/entomology-history)

The UC Davis Department of Nematology officially joined the Department of Entomology on May 28, 2013.

Molecular geneticist-physiologist Joanna Chiu, Professor and Chair of the UC Davis Department of Entomology and Nematology, is the 2023 faculty recipient of the Chancellor's Award for Excellence in Mentoring Undergraduate Research.  

The three-pronged Chancellor's Award, launched in 1994, annually honors three outstanding mentors: a graduate student; a postdoctoral fellow or project scientist; and a faculty member.

Professor Chiu, who joined the faculty in 2010, focuses her research on the molecular and cellular biology of circadian rhythms and seasonal rhythms.

Chiu lab member and doctoral candidate Christine Tabuloc, who will be receiving her PhD this month, nominated her for the award. A team of five other Chiu lab alumni submitted a group letter of recommendation.

"I joined Dr. Chiu's laboratory at the beginning of my second year here at UC Davis and remained a member of the lab for 3 years as an undergraduate, 2 years as a technician, and 6 years as a graduate student," Tabuloc wrote. "Throughout all my time in the Chiu lab, Joanna has never failed to amaze me with her kindness, patience, and her consistency and perseverance in helping all students, both in her lab and in other labs, succeed. I cannot think of anyone more deserving of this award than Dr. Chiu."

"Dr. Chiu welcomed me into her lab back in 2012," Tabuloc related. "I had just finished my first year of college, and I had virtually no research experience. Despite this, Joanna took a chance on me and invited me to join her lab. Throughout the years, Joanna has taught me many skills—both at the bench and skills that translate outside the lab and even beyond academia. Joanna has taught me everything I know from performing an experiment with all the proper controls to mentoring students and giving effective and clear presentations. What makes her so outstanding is her commitment to helping us improve as scientists and researchers and preparing us for our future career endeavors."

"She has taught me many technical skills at the bench, but more than that, she has taught me how to be an effective teacher and mentor to the undergraduate students I work with. She has encouraged me to learn new molecular techniques that are in high demand so that I will be prepared and competitive for jobs after I graduate. ;a I am immensely grateful that Joanna took a chance on me—someone who didn't even know what a pipet was—and work tirelessly to help me be the best scientist I can be...It is her consistent encouragement and constructive criticism that has allowed me to grow into the scientist I am today. After 11 years under her wing, I am leaving UC Davis with a B.S and soon, a PhD, and I owe all my success to Dr. Chiu and her incredible mentoring. It is because of her that I am an author on 14 publications—2 of which I authored as an undergraduate—and that I can be competitive in the job market."

Tabuloc praised Professor Chiu for teaching her effective communication, organization, time and personnel management, and resilience.

"One thing that I find unique about Joanna is her ability to see our potential before we even see it in ourselves," Tabuloc wrote. "Joanna often says that once we step into the doors of the lab, we are no longer students rather, we are scientists. She encourages us to think like scientists and gives everyone equal opportunity to pursue their scientific questions of interest and carry out independent projects."

"Not only have I experienced Dr. Chiu's mentorship first-hand, but I have also had the privilege of watching her mentor all the undergraduate students that have joined her lab throughout the years. In fact, since my time here, I have watched at least 35 undergraduates be mentored by Joanna, and many of these students were authors on publications in peer-reviewed journals such as Scientific Reports, Journal of Pest Science, BMC, Ecology, Current Biology, Nature Communications, Journal of Economic Entomology, and PLOS Genetics. More so, a true testament to her success as an undergraduate mentor are her students' successes: furthering their education at academic institutions such as Cornell, Stanford, Columbia, UCB,  and UCLA or landing industry jobs at companies such as 10X Genomics. Many of these students still keep in contact with Dr. Chiu, and she continues to provide advice and guidance such as reviewing resumes and helping them prepare for interviews. Joanna is not just our mentor when we are at UCD, she is our mentor for life."

Group Letter. The former lab members who teamed to write the group letter, all praised her impactful influence--her mentoring, her encouragement, her constructive feedback, and her strong support:

• Lisa Soyeon Baik, now a postdoctoral fellow at the Carlson lab, Department of Molecular, Cellular, and Developmental Biology, Yale University
• Daniel Ewels-Labolle, PhD student at Cornell 
• Jessica West, PhD student at Cornell
• Katherine "Katie" Freitas, PhD student at Stanford University
• Kiya Jackson, who received her bachelor's degree in biological sciences,  then joined the UC Davis Postbaccalaureate Research Education Program, and will be heading to UCLA for her PhD

"She helped me to gain confidence and to envision myself as a scientist. She not only gave me a start in my scientific career, but her mentorship has far exceeded my time in her laboratory. She has continually supported me through graduate school and now as a postdoctoral researcher."--Lisa Soyeon Baik

"I can say without a shadow of a doubt that I would not have been able to get to where I am now without Joanna's mentorship, advice and overwhelming support."--Daniel Ewels-Labolle

"As a PhD student at Cornell, I am immensely grateful for the training I received as an undergrad from Dr. Chiu. Not only did she train me thoroughly in basic biochemistry and molecular biology techniques, but she also pushed me to be independent and think critically about my science, skills essential for graduate school."--Jessica West

"Beyond teaching me practical research skills, Dr. Chiu helped to spark the most important thing a person needs to be a successful scientist: pure joy in the pursuit of knowledge."--Katie Freitas

"I believe Dr. Chiu is a valuable mentor for undergraduate researchers because she offers her time and expertise to train well-rounded scientists, regardless of the stage at which they start their career and regardless of what career they hope to pursue."--Kiya Jackson

Chiu joined the Department of Entomology and Nematology in 2010 as an Assistant Professor, and advanced to Associate Professor and Vice Chair in 2016, and to Professor and Vice Chair in 2021. She was named one of 10 UC Davis Chancellor's Fellows in 2019, a five-year honor awarded to associate professors who excel in research and teaching. The UC Davis Academic Senate honored her with a Distinguished Teaching Award, Graduate/Professional category, in 2022.

Chiu co-founded and co-directs (with professors Jay Rosenheim and Louie Yang) the campuswide Research Scholars Program in Insect Biology, launched in 2011 to provide undergraduates with a closely mentored research experience in biology. The program's goal is to provide academically strong and highly motivated undergraduates with a multi-year research experience that cultivates skills that will prepare them for a career in biological research.

Chiu received her bachelor's degree in biology and music from Mount Holyoke College, Mass., and her doctorate in molecular genetics in 2004 from New York University, New York. She trained as a postdoctoral fellow from 2004 to 2010 in molecular chronobiology at the Center for Advanced Biotechnology and Medicine, at Rutgers, the State University of New Jersey.

(See feature on Bug Squad)