Wikinews interviews biologist Chris Simon about periodical cicadas
Wednesday, June 12, 2013
Image: Stephen Chiswell.
In May, periodical cicadas with 17 years life cycle emerged on the East Coast of the USA after underground development as juveniles since 1996. Researchers and scientists worked to map and study the rare wave, and the locals prepared for the noisy event. First recorded in 1666, the Magicicada septendecim species recently emerged in 1979, 1996, this year, with a next wave due in 2030.
This week, Wikinews interviewed Chris Simon, an ecology and evolutionary biologist at University of Connecticut, about the cicadas.
((Wikinews
)) What caused your initial interest in periodical cicadas?
- Chris Simon: As an undergraduate student, I was interested in the formation of species so when I went to graduate school I looked for a study organism that was likely to be in the process of forming new species. I chose periodical cicadas because they are broken up into reproductively isolated broods (or year classes). Reproductive isolation leads to speciation so I planned to study biochemical differences among the broods.
((WN)) You study the emergence of the periodical cicadas. What do you study? What observations are you making?
- CS: We record exactly where each cicada population emerges (using GPS automated mapping and crowd sourcing). We record the presence or absence of each of the three morphologically distinct species groups of periodical cicadas (Decim group, Cassini group, and Decula group). We collect specimens for DNA analysis. We look for cicadas coming up one and four years early and late. We dig up cicada nymphs and monitor their growth rates.
((WN)) What equipment do you use?
- CS: Nets, shovels, automated GPS recorders, cameras, laptop computers, automated DNA sequencers.
Image: Chris Simon.
((WN)) Do you study the periodical cicadas with anyone else? What is their role?
- CS: Yes, there are a large number of people studying periodical cicadas in my lab and in other labs. My lab is made up of Research Scientists, Postdoctoral Researchers, a technician, graduate students, and undergraduates. Research Scientist John Cooley is the leader of the GPS mapping project; he invented the automated GPS recorder; he built our crowd-sourcing website, and he is instrumental in public outreach. Postdoctoral research David Marshall also participates in the mapping project and leads the part of the research related to the mapping of stragglers. John and Dave and Technician Kathy Hill all study periodical cicada mating behavior and conduct mating and hybridization experiments. One of my graduate students Beth Wade has participated in the nymph collections and will soon start genetic work involving genome wide association mapping designed to locate genes related to life cycle. My graduate student Russ Meister is studying the genes of the bacterial endosymbionts of cicadas. My current undergraduate honors student Erin Dwyer is also studying the development of Magicicada nymphs and is helping to design a lab exercise for college students around the eastern US to do the same. Many of my past undergraduate students have studied the biochemical genetics and development of periodical cicadas. See the Simon Lab website.
- CS: We are collaborating with Teiji Sota at the University Kyoto and Jin Yoshimura at Shizuoka University in Japan. They are studying the phylogeography of Magicicada. We are collaborating with John McCutcheon of the University of Montana who is studying the endosymbiont genomes.
- CS: We are also collaborating with ecologists Rick Karban and Louie Yang, both professors at UC Davis who have an interest in cicada population dynamics and nutrient cycling in the ecosystem.
((WN)) You studied the periodical cicadas in 1979 and 1996 too. What changes with time?
- CS: I have studied periodical cicadas since I was a student back in 1974. What changes with time is increased human development constantly shrinking the patch size of cicada populations.
((WN)) What are your thoughts on the long life span of the periodical cicadas? Why could it be so? What advantages and what disadvantages does it have?
- CS: Most or all cicadas have long life cycles compared to your typical annual insect. Examples have been found of two-year to 9-year cycles in different species. Periodical cicadas evolved an even-longer life cycle and I think that part of this relates to the evolution of their synchronized life cycles and peculiar safety-in-numbers strategy for survival. To become synchronized, periodical cicadas had to evolve an exact length life cycle and all adults would have to appear in the same year. Because the nymphs grow at different rates underground, a longer life cycle and a way of counting years must have evolved so that the individuals that get to the last nymphal (underground juvenile) stage first would wait long enough for all other individuals in the population to become ready to emerge.
((WN)) News reports mention this is 'Brood II' of the periodical cicadas. What are the distinctive features of this specific species and what is its full scientific name?
- CS: The same species exist in multiple broods. No species is restricted to Brood II. The three species present in Brood II are: Magicicada septendecim, M. cassini, and M. septendecula. These same three species are found in every 17-year brood (except the farthest north which only has M. septendecim).
Image: Chris Simon.
((WN)) At what depth do the cicadas juveniles live underground?
- CS: Most live within the top foot of soil but some have been found deeper. We do not know if they go deeper in winter. We need to do much more digging to understand the nymphs.
((WN)) How do people prepare for the cicada emergence?
- CS: Of course various people prepare in different ways. Ideally, everyone prepares by studying information available on the web (especially on our websites Magicicada Central and Magicicada.org).
((WN)) Do cicadas affect transport in the local area?
- CS: No, not really. Occasionally individuals can be seeing flying across highways and sometimes they smash into cars.
Image: Chris Simon.
((WN)) Do cicadas usually stay outside or do they also invade houses too?
- CS: They stay outside. One might accidentally fly in through an open window but that would be rare.
((WN)) What do the cicadas eat?
- CS: Cicadas suck xylem fluid (the watery fluid coming up from the roots of plants) in deciduous forest trees and herbs. Essential amino acids in the cicada diet are supplied by their bacterial endosymbionts. There are two species of endosymbionts. One makes 8 essential amino acids and one makes two essential amino acids.
((WN)) Do cicadas damage crops or city vegetation? What damage?
- CS: Cicadas do not chew leave so they do not damage crops like other insects. They can inflict some damage by their egg laying. Cicadas lay eggs in pencil-sized tree branches. If there are not enough branches available, too many female cicadas may lay eggs in a single branch weakening it and making it susceptible to breakage by wind. This can sometimes cause damage in fruit orchards. If the branches break, the eggs die so this behavior is selected against by natural selection.
((WN)) Thank you.
- CS: You're welcome. I am happy to have this opportunity to communicate with your readers!
Sources
- Zach Howard. "They're back: 17-year cicadas to swarm from Georgia to New York" — Reuters, May 6, 2013
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