What’s Corn Got to Do
with It?: The Complexity of the Interaction between Non-native and Native
Species in the Midwest
Tallgrass prairie is the native
landscape of central Iowa and much of the Midwest. At one point, Iowa was
almost completely tallgrass prairie and today, less than 1% remains. Mainly, corn
and soybean farming has converted the natural landscape into farmland, and a great
deal has also been urbanized. Such drastic change in vegetation is accompanied
by a number of other changes, as well. Specifically, modifying the vegetation
also modifies the entire ecosystem and the behavior of animals.
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| An adult corn-rootworm beetle on a a kernel of corn Photo credit: Marlin E. Rice |
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| A Grinnell College Ecology student setting traps in a flowerbed. Photo credit: Elle Silverman |
“An Edge Effect Caused by Adult
Corn-rootworm beetles on Sunflowers in Tallgrass Prairie Remnants”[1]
investigates the effects of a common corn pest on native sunflower populations
in surrounding prairies. Specifically, the research was conducted in
Southeastern Minnesota and like much of the Midwest, has a great deal of Zea mayes or corn and very little
natural prairie left. Thus, the authors set out to examine the relationship
between the corn pest, adult corn-rootworm beetles, and the native sunflower
populations in these remnant prairies. The research had both a field study
component and a controlled laboratory component. In the field, the authors
observed the damage done by the beetles on sunflowers in varying proximities to
corn fields and found predictably, that the damage done was worse closer to the
corn. In the lab, the sunflower heads were enclosed in a bag with either 0, 2,
or 4 adult beetles in order to study the direct effects of the beetle foraging
on sunflower growth and reproduction. All in all, the authors found that the
beetle may interfere with the reproduction of sunflowers, especially given the
small size of most prairie remnants. This research highlights some important
aspects of how native versus non-native vegetation affects one another. Namely,
a pest of a non-native species can adapt to the detriment of a native species.
Whether or not the beetle is undergoing or has undergone evolutionary
adaptations, or is just flexible in its foraging, is another interesting
question for another blog post to answer.
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| Ecology students setting traps in reconstructed prairie at Grinnell College. Photo credit: Elle Silverman |
This paper ties in nicely with the
research we are conducting at Grinnell College. Our research seeks to examine
the effects of non-native flower beds versus native reconstructed prairie on
beetle abundance and diversity. We hypothesized that beetle diversity and
abundance would be greater in native prairie as compared to the non-native
vegetation because it is the natural landscape of central Iowa. With that being
said, McKone et al. (2008) complicates the notion that native prairie supports
greater diversity and abundance of beetles. Their findings demonstrate that
beetles and other beasts are either inherently versatile in foraging and/or good
at adapting to changes in vegetation. All in all, reflecting on both the McKone
paper and our research, the theme of human activity affecting ecosystems stands
out. By planting so much corn, not only have humans limited the native
tallgrass prairie, but also all of the various species’ interactions. These
interactions are complex on a microlevel and affect the ecosystem as a whole.
Thus, I hope that the McKone’s 2008 paper and the research we are conducting at
Grinnell College illuminate the importance of understanding some effects of
non-native and native species’ interactions, as well as the role that humans
play in these interactions.
References
Mckone, Mark J., et al. "An Edge Effect
Caused by Adult Corn‐Rootworm Beetles on Sunflowers in Tallgrass Prairie
Remnants." Conservation
Biology15.5 (2001): 1315-1324.
It would be interesting to see if there are any cases in which native ecosystems are affected negatively because monocultures draw native pollinators and other plant-symbiotic insects away from them. On the other hand, maybe there are cases where native beetles that normally predate certain plants are drawn to non-native monocultures, taking pressure off of the native plant community and possibly even shifting its plant composition. Or maybe most beetles are pretty flexible and just don't care.
ReplyDeleteMcKone's paper reminds me that the type of edges around prairie reconstructions/remnants have important effects. The blog entitled "Living on the Edge" (by Toni Andronski) presented a paper that demonstrated cropland edge better promoted healthy prairie species populations than woodland edges, but McKone's paper suggests one danger of cropland edges. Insects that live in crops may damage the prairie vegetation and decrease diversity. These papers together indicate how important it is to have many studies on different species to gather sufficient knowledge for conservation efforts.
ReplyDeleteThis study also highlights important evolutionary issues; do insects adapt to a certain host species and specialize? The corn root worm beetle seems to be able to feed on many different species, not just corn. It would be interesting to determine how specialized most beetles are - is the corn root worm beetle unusual? I am also interested in how planted flower beds compare to monocultures, such as corn? Do they decrease insect diversity in the same way?
I find the idea of pollinator adaptations influencing the native vs. non-native vegetation issue very interesting. So far, I only recall speaking of native vs. non-native vegetation in terms of differential adaptations in the plants themselves, including dispersal abilities. Given that McKone et al. study beetle distribution in two monocultures, it would be interesting to see if your project, which is studying two polycultures (although they are not crops), imitates the same pattern.
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