Abiotic factors affect insect growth and the onset of diapause
Contributed by: Carolyn Graham @_Carolyn_Graham
Keywords
Ability, Agriculture, Agroecosystem, Animals, Community ecology, Consumption, Ecology, Field, Fundamental research, Historical figure, Interactions, Lab, North America, Population ecology, Terrestrial
Slides
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Resources
Beck, S. D., & Apple, J. W. (1961). Effects of Temperature and Photoperiod on Voltinism of Geographical Populations of the European Corn Borer, Pyrausta nubilalis. Journal of Economic Entomology, 54(3), 550–558. https://doi.org/10.1093/jee/54.3.550
Notes
Slide 1: Researcher’s Background
Dr. Beck was a professor of insect ecology at the University of Wisconsin Madison, where he researched insect physiology and plant-insect interactions.
Biography in brief
Stanley D. Beck was born in 1919 in Portland, Oregon. He grew up in Washington state, where he enjoyed hiking and fishing in the mountains. He graduated magna cum laude from Washington State University in 1942, and served in the US Navy from 1942 to 1945. He then went on to get his Masters and Doctorate degrees in zoology from the University of Wisconsin, where he subsequently obtained a position as a professor. Professor Beck contracted Polio in 1952, and as a result he became a wheelchair user with limited mobility in his arms for the next 45 years of his life. Despite his illness, Beck continued to teach at Wisconsin Madison until his retirement in 1989.
He was known as an exemplary teacher and mentor, creating several graduate courses at UW and authoring books on scientific communication and theory. Dr. Beck participated in countless professional activities and conferences, and served as the president of the Entomological Society of America in 1982 where he emphasized scientific freedom and countering anti-science movements. Dr. Beck received many awards and accolades throughout his lifetime, including the 1962 Founders’ Memorial Award of the Entomological Society of America. In 1988, he was elected to the National Academy of Sciences. After his death in 1997, the ESA established the Stanley D. Beck Fellowship for disabled students in entomology in his honor.
During his time as a professor and member of the Entomological Society of America, Stanley Beck served on committees that tackled issues of ethics and disability. He was determined and persistent in his research endeavors, working around his physical limitations by typing his numerous publications with a single finger. He was quoted by Reginald H. Painter as being “one of the heroes of the human spirit” for his contributions to science in the face of his disability. Stanley himself is quoted to have said “Once you have adjusted yourself to the realization that you are—slightly incapacitated, then the road back is less difficult. For, sooner or later, you wake up to the realization that there are not many alternatives. You either must readjust your life or give up completely.”
Outside of science, he enjoyed “reading, music, plays, traveling, games, and theological discussions,” and even wrote two fiction novels, one of which was published.
Is (or was) their research under-valued because of their identity?
Slide 2: Research Overview
Take home message of study
Beck and Apple (1961) demonstrated that different populations of the European corn-borer (O. nubalis) geographically distributed across the midwest, and thus exposed to different light levels and temperatures, entered diapause at different rates.
Study system
Top: adult European corn-borer (O. nubalis). Bottom: Corn-borer larva. The European corn-borer is an introduced pest species that damages many agricultural crops in the Midwest.
Slide 3: Key Research Points
Main figure
Using Dr. Beck’s aseptic growth medium, borers from Wisconsin and Ontario populations were raised under varying temperatures and photoperiods, and the diapause incidence was measured as the percent of larvae that failed to pupate. All borers were initially started at 30℃ and continuous light.
Curve A represents Wisconsin and Ontario borers that were grown under the initial conditions, 100% of which pupated (0% diapause).
In Curve B, Wisconsin borers were transferred to 18.5℃ and continuous light, and again there was no diapause.
Curve C is Wisconsin borers that were exposed to conditions of 18.5℃ and a 9.5 hour photoperiod after day 9. Only 25% had pupated within 30 days. The plateau represents initial diapause of the larvae.
Curve D is Ontario borers that were exposed to conditions of 18.5℃ and a 9.5 hour photoperiod after day 9. Only 7% had pupated within 30 days, corresponding to a diapause incidence of 93%. The plateau represents diapause of the larvae.
After day 30, the larvae were returned to 30℃ and continuous light. The Wisconsin larvae resumed pupating more quickly than the Ontario larvae.
This work demonstrated that populations of O. nubalis with different geographic origins respond differently to variation in temperature and more dramatically to variation photoperiod, where the Ontario population entered diapause more readily and then responded to increased light more slowly. More broadly, “the incidence of diapause was positively correlated with the latitude of the population source”.
Societal Relevance
In this research, Dr. Beck demonstrated that geographically separated populations of European corn borers can have markedly different developmental characteristics. These findings went on to inspire the North Central Regional Project to further investigate the “geographical differences in the behavior and seasonal development of the European corn borer,” research that has been active for many years.
On a broader scale, Dr. Stanley Beck’s research informed much of our understanding of host plant resistance to insects, photoperiodicity of insect development, and insect circadian rhythms. Dr. Beck conducted the “first systematic studies of the chemical basis of plant resistance,” using the European corn-borer (Beck, 1957; Beck and Smissman, 1960). He is credited with developing several of the first artificial growth mediums for insect rearing, paving the way for experiments necessitating mass-rearing of insects or bioassays of specific plant allelochemicals. He was additionally the first to demonstrate how plant-derived chemicals impact the growth and survival of insect larvae. His use of artificial diets that contained plant extracts or individual compounds allowed him to clearly demonstrate cause-and-effect relationships between insect performance and their nutrition.
