Every 17 years, the Brood X periodical cicadas of the genus Magicicada (M. cassini, M. septemdecim, and M. septemdecula) emerge in Indiana and western Ohio. Like many other species, these cicadas are facing the effects of habitat destruction and climate change. Magicicada needs a specific ground temperature in order to emerge. Given that warmer temperatures have been occurring earlier in the year, changes in Magicicada spp. phenology of emergence may occur. Alongside climate change, habitat loss has already shown harmful effects on Magicicada broods as it caused the extinction of Brood XI and may also be causing a decline in Brood X. Our goal was to assess whether the phenology of the Brood X has changed between 1987 and 2021, and whether Brood X has exhibited a population decline. We collected phenology and population density data during the cicada emergence in 2021 at 9 sites in southwestern Ohio, representing different habitat types (woodlots, fencerows, urban sites, and a primary forest). We combined these data with those collected by other researchers in 1987 and 2004. To assess changes in phenology, we used 6 emergence traps per site and compared the emergence peaks between 1987 and 2021. To assess changes in population densities, we counted the number of holes in roughly ten 1m2 quadrats at each site. We found there has been a gradual decrease in cicada holes at our primary forest site and woodlots since 1987, but there had been a gradual increase in cicada holes in the fencerows since 1987. We also found that the mean peak emergence date in 2021 occurred later than the mean date in 1987, which contradicts our expectation. Our unique dataset comprising population data for three generations of periodical cicadas contributes to understanding population changes in these long-lived insects.
Authors: Brianna Louis, Alfredo Ascanio, Andrew Canizzaro, Victor Fitzgerald, Jason Bracken, Thomas Crist, Nicholas L. Rodenhouse, and Tereza Jezkova
Advisor: Tereza Jezkova, Biology
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