12/1 at 6 pm – Insect Metamorphosis by Dr Lynn Riddiford

“Unraveling the mystery of the hormonal control of insect metamorphosis”


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Dr. Lynn Riddiford
Dr. Lynn Riddiford

Dr. Lynn Riddiford will talk to us about Metamorphosis. Dr. Riddiford is an entomologist and developmental biologist. She was the first female faculty member in the Harvard Biology Department, where she served as an assistant and associate professor. Currently she is an emeritus professor at the University of Washington, Friday Harbor Laboratories and Department of Biology. In 1997, she was the first awardee of the Recognition Award in Insect Physiology, Biochemistry, and Toxicology from the Entomological Society of America. She studies the endocrinology of insects, specifically the tobacco hornworm.

In higher insects, metamorphosis is of a period of profound cellular changes as a feeding, growing larva transforms into an active, reproductive adult.  Two hormones oversee this transition, the steroid molting hormone, ecdysone, and the “status quo” sesquiterpenoid hormone, juvenile hormone (JH).  JH both directs the suite of genes activated by ecdysone exposure and also allows proliferation but suppresses differentiation of latent embryonic primordia that will give rise to adult structures.  The molecular pathways underlying ecdysone action are well known, but those for JH just beginning to be understood.  I will first discuss the history of the discovery of these hormones and their roles in the regulation of metamorphosis.  Then I will discuss the recent findings on the molecular basis of this control.  

My research over the years on molting and metamorphosis in the tobacco hornworm, Manduca sexta, was critical for its serving as a model for the endocrine regulation of post-embryonic development of insects.  One major theme has been to understand how juvenile hormone (JH) prevents the metamorphosis of a caterpillar to a moth and how it regulates embryogenesis.  We also have contributed to the application of JH as an Insect Growth Regulator (IGR) currently used in mosquito and flea control and some integrated pest management schemes for agricultural lepidopteran pests.  Hormones and behavior in Lepidoptera and sex pheromone reception were other early themes in my research. At Janelia, I studied the hormonal regulation of neurodevelopment and behavior in Drosophila.  Presently, at Friday Harbor Laboratories, I am continuing to study the role of JH in metamorphosis of the Drosophila nervous system and studying the regulation of metamorphosis in Crustacea.  Jim Truman and I are continuing our collaboration on the evolution of metamorphosis. We are particularly interested in how the hormonal control of embryonic development in ancestral insects may have driven the evolution of complete metamorphosis. Currently, we are studying the effects of JH on embryonic and early nymphal development of silverfish. 

B.A. in Biochemical Sciences, Radcliffe College (1958); Ph.D. in Zoology and Chemistry, Cornell University (1961); Research Fellow in Biology, Harvard University (1961-63; 1965-66). Instructor in Biology, Wellesley College (1963-65); Assistant (1966-71) and Associate Professor (1971-73) of Biology, Harvard University; Associate Professor (1973-5) and Professor (1975-2003) of Zoology and Virginia and Prentice Bloedel University Professor from 2000-2005, Professor of Biology (2003-7), emerita (2007-present), University of Washington. Senior Fellow, Janelia Research Campus, Howard Hughes Medical Institute (2007-2016).  Honors: NAS member; Fellow, American Academy of Arts and Sciences, AAAS, the Entomological Society of America (ESA), Royal Entomological Society, John S. Guggenheim Foundation (1979-80), Overseas Fellow, Churchill College, Cambridge University (2000-1). ESA Recognition Award in Insect Physiology, Biochemistry, and Toxicology (1997). G. J. Mendel Honorary Medal for Merit in the Biological Sciences (Czech Republic Academy of Sciences, 1998); Vollum Award for Distinguished Accomplishment in Science and Technology (Reed College, 2011); Washington State Academy of Sciences (2018); ICIPE@50 Achievement Award, ICIPE (2020). 

Chairman, Scientific Program Committee, Governing Council, International Center for Insect Physiology and Ecology (ICIPE), Nairobi, Kenya (1989-91); President, American Society of Zoologists (1991); President, Council for the International Congresses of Entomology (2000-4); President, Council of the International Federation of Comparative Endocrinological Societies (2001-5). 

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