April showers bring June flowers, but

Insect physiologist Swapna Priya Rajarapu

spring also brings seminars about insects.

 

Insect physiologist Swapna Priya Rajarapu, a postdoctoral research scholar in the Dorith Rotenberg laboratory at North Carolina State University, Raleigh, will present the UC Davis Department of Entomology and Nematology's first seminar for the month of April. The department hosts online seminars at 4:10 p.m. on Wednesdays through June 2.

 

Rajarapu will speak on "Insect-Plant Molecular Interactions: Stories from Invasive Insects to Disease Vectors" at 4:10 p.m., Wednesday, April 14. Professor Diane Ullman is the host. Access this link to register for the Zoom event. 

 

In the Rotenberg lab, she works on understanding the molecular interactions of an insect vector and their virus and their ability to modify the host plants. 

 

A first-generation college student, Rajarapu holds two biochemistry degrees from Osmania University, India: her bachelor's degree (2006) and her master's degree (2008). She obtained her doctorate in entomology in 2013 from The Ohio State University, working with Professors Daniel Herms and Larry Phelan. Her dissertation: "Integrated Omics on the Physiology of Emerald Ash Borer."

Spring Seminar Schedule

Here's the seminar line-up for the spring quarter. All are scheduled from 4:10 to 5 p.m. on Wednesdays. 

April 21 
Chris Hamilton
University of Idaho, Department of Entomology, Plant Pathology and Nematology
Title: "Understanding Aphonopelma Diversity Across the Madrean Pine-Oak Woodlands Hotspot by Integrating Western Science and Traditional Ecological Knowledge (TEK)"
Host: Jason Bond
Zoom info

April 28
Ellen Currano
University of Wyoming, Department of Geology and Geophysics
Title: "Ancient Bug-Bitten Leaves Reveal the Impacts of Climate and Plant Nutrients on Insect Herbivores"
Host: Emily Meineke
Zoom info

May 5 
Gabe Zilnik
USDA-ARS Wapato, Wash., Temperate Tree Fruit and Vegetable Research
Title: "Improving Tobacco IPM with Machine Learning"
Host: Madi Hendrick
Zoom info

May 12
Margarita López-Uribe
Pennsylvania State University, Department of Entomology
Title: "Ecoevolutionary Consequences of Crop Domestication on Plant-Pollinator Interactions"
Host: Rachel Vannette
Zoom info

May 19
Manuela Ramalho 
Cornell University
Title: "Exploring Connections Among Microbial Community, Ecology and Phylogenetic History of Ants" 
Host: Marshal McMunn
Zoom info

May 26
Javier Ceja Navarro
Lawrence Berkeley National Laboratory, Biological Systems and Engineering 
Title:  (Pending) 
Host: Rachel Vannette 
Zoom info

June 2 
Alexandra Harmon-Threatt
University of Illinois Urbana-Champaign, Department of Entomology 
Title: (Pending) 
Host: Neal Williams 
Zoom info

For any questions, email Ian Grettenberger (imgrettenberger@ucdavis.edu).

Lynn Kimsey, director of the Bohart Museum of Entomology (Photo by Kathy Keatley Garvey)

As director of the Bohart Museum of Entomology (which is celebrating its 75th anniversary this year), Kimsey identifies about 2000 insect specimens a year for colleagues, students, the museum and other museums. The Bohart curates some 30,000 new specimens to the museum annually. 

A UC Davis alumnus (bachelor's degree and doctorate), Kimsey joined the entomology faculty in 1989. Since 1990, she has administered the Bohart Museum, which now houses some eight million insect specimens and is the seventh largest university insect museum in North America.

Her areas of expertise? Insect biodiversity, systematics and biogeography of parasitic wasps, urban entomology, civil forensic entomology, and arthropod-related industrial hygiene. She has served in numerous leadership roles at the international, national and local level, including two terms as president of the International Hymenopterists, board member of the Natural Science Collections Alliance, and interim chair and vice chair (twice) of the UC Davis Department of Entomology (now the Department of Entomology and Nematology).

Last year her peers selected her for the 2020 C. W. Woodworth Award, the highest honor given by the Pacific Branch, Entomological Society of America.

Take her page on Urban Myths on the Bohart Museum website where she dispels bizarre myths with a succinct dose of humor.

Such as the urban myth, "Female mantids always eat males they mate with." Her response: "Only if the male isn't fast enough!"

Urban myth: "Camel spiders scream like babies, inject toxins and prey on GI's in Iraq."
Kimsey reality: "Not true at any level."

Urban myth: "Twenty-five percent of the protein in our diet is from swallowing spiders that crawl in our mouth at night."
Kimsey reality: "This never happens."

Urban myth: "Ultrasonic devices help keep pests out of your kitchen."
Kimsey reality: "False, few insects can hear, certainly not cockroaches."

Urban myth: "Earwigs will crawl in your ear and lay eggs in your brain."
Kimsey reality: "They sometimes do crawl in ears by accident, but do not lay eggs."

Urban myth: "Bedbugs bore, burrow, dig and fly."
Kimsey reality: "No, they can only walk or scurry."

Urban myth: "Butterflies and moths can't fly if you rub the scales off their wings."
Kimsey reality: "Not true, they can fly."

The Bohart director also fields questions about spiders, including the urban myth that brown recluse spiders are "common in California." No, she says, "they are not found anywhere near California."

No doubt that Kimsey, known as "The Wasp Woman" for her expertise in Hymenoptera, soon will be targeting myths about those Asian giant hornets, aka "murder hornets," that are supposedly mass-targeting 328 million people in the United States.

Professor Wittko Francke at the UC Davis seminar on Dec. 8, 2010. (Photo by Kathy Keatley Garvey)

“Nature is more a world of scents than a source of noise.”

So said renowned organic chemist Wittko Francke (1940-2020) of the University of Hamburg, Germany, when he presented a UC Davis Department of Entomology and Nematology seminar at Briggs Hall on Dec. 8, 2010. 

He was quoting Jacques Le Magnen (1916-2002), who pioneered research on olfaction and taste.

Professor Francke said that insects communicate in a chemical language or chemical signals. Scientists have long known that methods that can attract or repel insects have important applications for agricultural pests and medical entomology.  

He told the crowd how a queen bee secretes compounds that regulate development and behavior of the colony, and how an orchid releases the scent of a female wasp to attract male wasps—activities that result in pollination. He also touched on the “calling cards” of a number of other insects, including bumble bees, wasps, pea gall midges, stingless bees, bark beetles and leafminers, and pointed out that plants, too, send chemical signals.

Sadly, Francke passed away Dec. 27, 2020 at age 80. 

"The scientific community loses a very productive and passionate researcher, a great colleague, mentor and friend," wrote former student Jan Bergmann of the Pontifica Universidad Católica de Valparaíso, Chile,  a past president of the Latin American Association of Chemical Ecology. Bergmann's tribute  appears on one of @ALAEQ2 tweets.

And sadly, the chemical ecologist who introduced Francke at the UC Davis seminar--Steve Seybold of the USDA Forest Service, Pacific Southwest Research Station, Davis, and an affiliate of the UC Davis Department of Entomology and Nematology--died Nov. 15, 2019 at age 60.

No stranger to UC Davis, Francke collaborated with chemical ecologist Walter Leal, a UC Davis distinguished professor of molecular and cellulary biology and former chair of the entomology department, on attractants for navel orangeworm. In his talk, Francke mentioned Leal's discovery of a sophisticated mechanism for the isolation of the chemical communication channels of two species of scarab beetles.

To celebrate the life and legacy of Francke and his work, Leal is organizing an online symposium set for 10 a.m. (Pacific Time) on Saturday, April 3.  Register to participate or attend at https://tinyurl.com/3jsfcub7

Francke was one of the great pioneers shaping chemical ecology and the International Society of Chemical Ecology (ISCE), said Leal, an ISCE past president.

Born Nov. 28, 1940 and raised in Reinbek, near Hamburg, Germany,  Francke studied chemistry at the University of Hamburg, obtaining his doctorate there in 1973. His thesis: "The Aggregation Pheromone of the Bark Beetle, Xyloterus domesticus.  He was appointed professor of the Institute of Organic Chemistry of the University of Hamburg in 1985 and had served there until after his retirement. 

A colleague once called him "The Mozart of Molecules," which Bergmann noted, "summarizes eloquently the admiration of many had for his work, which is documented in more than 450 scientific publications." Among Francke's many global honors: the 1995 ISCE Silver Medal. 

Francke was not only an "outstanding, hard-working scientist" but a "loving husband, father of two children and grandather of four grandchildren," Bergmann wrote. "He was also a person with incredible kindness and generosity....He enjoyed bringing people together and deeply cared about his students, many of which stayed in touch with him long after they left his research group. His legacy will live on in those of us he has inspired and guided in so many ways."

Former Francke student Stefan Schulz, a professor at the Institute of Organic Chemistry, Germany, an ISCE past president,  wrote on the symposium's registration page: "Even in his early years, he showed some characteristics many associates with him, such as energy, determination, imagination, and creativity. Despite several offers, he stayed his whole academic career at the University of Hamburg, where he finally became a Full Professor and served different functions, including Dean of Chemistry. He always liked to teach, which he did happily even in his later years." 

Max Planck Institute for Chemical Ecology tweeted Dec. 29, 2020: "Wittko Francke's death is a severe loss for the field of Chemical Ecology. He was not only a great chemist, but he also had a large influence on the development of our institute being a key member of the advisory committee that set up our institute."

On April 3, the scientific and personal world of Professor Francke will come together to remember his life and legacy and pay tribute to "The Mozart of Molecules." 

UC Davis medical entomologist-geneticist Geoffrey Attardo

The species has now reached at least 17 California counties and its successful spread may be linked to its resistance to pyrethroids, according to newly published UC Davis research examining genetic markers of resistance at five state locations. 

The work, published in the current edition of Parasites & Vectors, a BioMed Central open-access medical journal, focuses on “determining how informative well-established genetic markers of resistance to pyrethroids are in predicting the resistance phenotype of individual mosquitoes of Aedes aegypti within a population,” said Attardo, the lead author.

“Specifically, we generated mosquito colonies from invasive A. aegypti populations from four locations in the Central Valley (Dinuba, Clovis, Sanger and Kingsburg) and from collections in the Greater Los Angeles Area,”  he said. “Mosquitoes from these populations have all demonstrated resistance to pyrethroid-type insecticides and we think this may be part of the reason why these mosquitoes have been so successful in spreading throughout California.”

 A. aegypti transmits such viruses as dengue, Zika, chikungunya, and yellow fever. Despite California's aggressive surveillance and treatment efforts, this species presents a “significant challenge to local control agencies,” the nine-member team wrote in their research paper, “Frequency of Sodium Channel Genotypes and Association with Pyrethrum Knockdown Time in Populations of Californian Aedes aegypti.“

The paper is online and publicly accessible at https://bit.ly/3vmUxXR.

“What was interesting was that while all the mosquitoes from California show resistance to pyrethroids, there is a lot of variability from one individual to the next in terms of the level of resistance, even when they are carrying genetically identical resistance mutations,” Attardo said. “In particular, there seem to be two levels of resistance in these populations. The two levels seem to represent a resistant group and a super resistant group. However, the proportions of resistant/super-resistant differ in the sampled mosquitoes from population to population.” 

Of particular interest was that mosquitoes carrying the resistance mutations at all five genetic locations were very resistant, he said. “However, there was also a large amount of unexplained variability in terms of the knockdown phenotypes demonstrated by mosquitoes of the same age and rearing conditions. We compared the knockdown times of mosquitoes positive for all five resistance mutations from different populations and found that these mutations account for only a proportion of the observed level of resistance. We believe that the unexplained variability is likely being mediated by the presence or absence of an undefined resistance mechanism.” 

Although A. aegypti was first detected in California in 2013, researchers believe that its arrival involved multiple introductions. Populations in Southern California are thought to have crossed the border from Mexico, while Central Valley populations may have been introduced, in part, from the southeastern United States. 

“Upon detection in 2013, the Consolidated Mosquito Abatement District implemented an integrated vector control management strategy which involved extensive public education, thorough property inspections, sanitation, insecticide treatment at larval sources and residual barrier spraying with pyrethroids,” the authors wrote. Despite their efforts, the species successfully overwintered and continued to spread, implicating that it arrived in California with genetic mutations “conferring resistance to the type I pyrethroid insecticides applied for vector control in California.” 

The co-authors include former UC Davis mosquito researcher Yoosook Lee, now at the University of Florida-Florida Medical Entomology Laboratory, Vero Beach; research entomologist Anthony Cornel and staff research associate Katherine Brisco of the Mosquito Control Research Laboratory, Kearney Agriculture and Extension Center and UC Davis Department of Entomology and Nematology; and Lindsey Mack, Erin Taylor Kelly, Katherine Brisco, Kaiyuan Victoria Shen, Aamina Zahid, and Tess van Schoor,  all with the UC Davis Department of Entomology and Nematology.

For more information and photos, see news story on "UC Davis Researches Examine Pyrethroid Reistance in Spread of Aedes aegypti," on the UC Davis Department of Entomology and Nematology's website.