Indiana University
Cicada Project

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IU cicada research supported by NSF grants DEB-0345331, BCS-0083546-001, and BSC-0227608


The Project

The goal of our NSF-supported research is to determine: Do periodical cicadas affect forest composition and dynamics? We are analyzing the effects of recent (2002-Brood XXIII, 2004-Brood X) periodical cicada emergences on forest succession. Brood X is among the largest insect emergences on Earth.

Brood X is centered in southern Indiana, but it is just one of many cicada broods that occur in the Midwest and in the eastern United States. (View a cicada brood distribution map for the eastern half of the United States from 1995-2019.)


suburban tree A major premise of our research is that human alteration of the landscape (forest fragmentation, disturbance, forest regeneration from abandoned land, maturing suburban landscapes) is increasing high quality cicada habitat in some areas, thus, leading to larger and more dramatic cicada emergences.

Indiana maps showing Brood X in nearly all counties in 1902, but missing from several northern counties in 1987 In contrast, in other areas cicada habitat is disappearing, leading to extinction of local populations. For example, cicadas have greatly declined in northern Indiana with its agricultural landscape and lack of forest cover.

 


Much is known about cicada biogeography, systematics, behavior, and predator satiation--but relatively little research has investigated their impacts on host trees and forest dynamics and how these effects depend on landscape patterns.

Our proposed research will test the hypothesis that community composition of successional forests is affected by periodical cicadas.

  1. We are contrasting forest community composition in a range of high-density to low-density cicada sites, potentially reflecting the past effects of one or more generations of cicadas.
  2. graph showing preferred plants for oviposition
    Mean (+ SE) oviposition index for each tree species separated by the two broods. Species are arranged from most to least susceptible by Brood X. Species with fewer than 30 individuals across all sites and those that occurred at only a single site are not shown. Not all species were sampled for both broods. Species that differed significantly (P < 0.05) in susceptibility to oviposition by the two broods are marked with an asterisk.
    cicada emergence holes

    emergence holes graph

    netting over trees

  3. We experimentally manipulated cicada colonization in selected sites by netting replicated blocks of early successional forest (less than 17 years old) during the Brood X emergence to reduce oviposition and subsequent root colonization. We are following the survival and growth of several thousand individual trees at numerous sites to determine whether there is an effect of cicadas, and whether it differs among tree species.
  4. In addition, we are exploring several possible mechanisms (resistance to damage, response to damage, indirect effects on herbivores and symbionts) by which periodical cicadas affect forest succession.
  5. Finally, in collaboration with Jim Speer, Assistant Professor of Geography, Geology, and Anthropology at Indiana State University (www.indstate.edu /gga/gga/javatest/f,s,s/Speer.html) we are using dendrochronology to determine whether past cicada emergences result in detectable patterns of tree ring growth, inhibition, and release that occur on a 17-year (or 13-year) cycle.

    dendrochronology instrument


These empirical approaches will improve our understanding of the ecological consequences of large-scale biotic disturbance events (such as periodical cicada emergences) on forest dynamics. Further, periodical cicadas may serve as a useful model for other less predictable biotic disturbances like gypsy moth, emerald ash borer, and oak wilt.




Revised: December 15, 2008


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