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The Picture of the Day from Science 360News Service today, March 22, is about the Asian tamarisk leaf beetle. The picture, as all the Science 360News Pictures of the Day, is lovely. Beautiful colors, succinct description.


The beetle (Diorhabda carinulata and Diorhabda sublineata), a natural pest of the tamarisk tree, is being introduced in the western U.S. as a biological warfare agent against the tamarisk tree--a species of tree introduced to the U.S. 100 years ago.


Makes sense. In its native habitats  (China, Mongolia, Russia, Tunisia, Egypt, and other parts of Asia, Africa, and Europe), the beetle keeps the tamarisk under control. And the tamarisk tree here in the U.S. needs to be controlled, even erradicated. The tamarisk is destroying native plants and ecosystems in the U.S. west. It displaces riparian woodlands, compromises habitat for wildlife, increases erosion and contributes to demise of water quality.It's also a highly flammable tree; so it increases wildfire activity. The tamarisk tree is bad news for the ecology of the western U.S.


But is introducing a beetle that, while a natural pest of the tamarisk tree, really a good solution? The beetle is also non-native to the very ecological system experts are trying to protect and restore. I'm not a biologist. I'm not a forester. I'm not a trained scientist of any kind. But I wonder, "So, once the tamarisk trees are destroyed, what native plants (or animals) will the beetle evolve to eat?" Sure, it may not be for another hundred years. But what new problems will we have introduced?


I'd like to think that the experts have wrestled with this question.


With my MSP2 hat on, I wonder if this would be a good question with which to prompt students to wrestle. Where and when have we introduced other non-native species? Why were those choices made? What have been the results? How do we make decisions about when the risk is worth the introduction? And can we extend the conversation outside of biology? What about ideas? Cultures? Attitudes?

Views: 14

Tags: biology, decision-making, ethics


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Comment by Mary Henton on March 31, 2011 at 9:34am

And one wonders what "does not significantly harm other species" means!

I hadn't read carefully enough about the anticipated equilibrium. Thank you for checking this through. But even so, I still wonder...

Comment by Mary LeFever on March 30, 2011 at 2:20pm
Great issue! Yes, the possibility of these beetles adapting is very possible given mechanisms of natural selection. The Wikipedia resources Mary linked to indicate the beetle is a specialist and that field studies in the US indicate it does not "significantly" harm other species. The sources also say that the invasive trees will not be eradicated, but that both the tree and beetle populations should reach equilibrium, keeping each other's populations low and in check. There are two beetle species, one better adapted to the US conditions than another, but that species is not establishing itself well. Seems like some genetic engineering could provide the best genes of both species into one and get what scientists are after! And one thing leads to another . . .
Comment by Mary Henton on March 22, 2011 at 1:26pm

Further thoughts about possible classroom connections: What goes into decision-making about practices to control? Who decides what needs to be controlled? Conventional, large-scale, monoculture farming has, over the decades, created the need to control weeds. Hence pesticides and herbicides and controlled (i.e., genetically engineered) seed. But who, actually, made those decisions? Where else in our history, or in a particular society, were decisions made about controlling? Who was in the conversation? Who wasn't? What were the immediate results? What were the long-term effects?


I know these are big questions. But they are questions that middle school kids can grapple with. They certainly understand the issue of control!


By the way I want to clarify that at the end of the first posting , here, I was not suggesting that bringing in new ideas, cultures, and attitudes is akin to introducing invasive species! My head was following along the lines of the theme of "outside the culture" or "outside the ecology." 



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