Grasshoppers Frightened by Spiders Affect Whole Ecosystem
A joint study between Yale University (YU) and the Hebrew
University of Jerusalem (HUJ), show stress in prey from a predator, could be
effecting crop production. Dr. Dror Halwena of the Department of Ecology,
Evolution and Behavior at HUJ, with the help of several colleagues from both
universities; used grasshoppers exposed to stress, to show the change in the
chemical structure of the insects. They found that when a grasshopper is
stressed from a spider, the grasshopper eats more. When this happens, the nitrate
levels of the grasshopper decrease, while carbon levels increase. So when the
grasshopper’s remains decompose into the soil, the plants have less nitrate
levels for food.
The team placed cages on vegetation and let the grasshoppers
feed. To measure the difference in stressed versus non-stressed they placed a
spider that had its ‘mouth’ glued shut into random cages. Even though the
spider couldn’t eat the grasshopper, it was still under stress. The stressed
grasshoppers proved to have a higher carbon to nitrogen ratio. When the dead
grasshoppers where placed into the soil, plant growth was greater in the soil
that contained stress free grasshoppers than in the soil containing the
stressed ones.
Article Link: http://www.sciencedaily.com/releases/2012/06/120614142737.htm
Here is the link to the actual research, I ended up using the transcripts from the PodCast interview with Dr. Dror Halwena http://www.sciencemag.org/content/336/6087/1434
I think you did a very nice job of getting this research into a tidy summary. From my quick reading of the transcripts it looks like it might have been a good idea to include that beyond just affecting the nutrients available to the plants, the carbon rich grasshoppers had a negative effect on the microbial make up of the soil too.
ReplyDeleteI also think that under the heading "why this is important" it'd be good to include something about how having predators in the environment does more than just control the number of grasshoppers. This seems important to me because if I were to make my own judgements about why this is important beyond what the research implies, I'd have to say that it's likely that we can't just use pesticide alone and expect that growth will be the best it could be.
Overall, this is a great summary of the research. I "got" the idea when I read this and it was short and simple enough that it really grabbed my attention.
Susan Andrus
Sweet topic! Very nice integration of findings and research methodology. Those two explanations can be hard to synthesize.I enjoyed your summary of the research, but I was left with one main question (which may be answered in the transcript, although I did not hear anything about it): what geographical location is most affected by this change in body chemistry that is induced by stress? Attacking the same question as above, but from a different direction: what crops are most damaged by this phenomena? I guess, theoretically, this change could happen anywhere an abundance of predators reside. Also, what causes there to be an abundance of predators (non-native species)?
ReplyDeleteThat's crazy. I think Ross posed some great questions above. Thanks for your feedback on my blog — I think you are right that it is not a science writer's place to suggest ethical stances. Good call.
ReplyDeleteI really liked your topic. The information was great for anyone looking into pregnancy prevention. I had totally forgotten about what my wife had to deal with. Thanks for the insight, and also making me appreciate how tough my wife is. :)
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