Crop Failures and Food Riots

In the spring of 2008, many news outlets reported that rice crop failures in East Asia could have been avoided. An infestation of the brown plant hopper is the cause for the crop failure. The science knowledge and biotechnology needed to breed resistant rice plants have been in existence for several years. However, funds were not available to mass produce these rice strains and get them into the hands of rice growers. This is one example of crop failure that, when combined with other agricultural woes, fueled food riots around the world, but especially among the poorest people in the least developed nations.

The New York Times published an article that comprehensively describes how this preventable tragedy happened – World’s Poor Pay Price as Crop Research Is Cut. As with most sociopolitical issues, a combination of circumstances over a long period of time must be considered if one is to accurately account for the current crisis. The article conveys the history of agriculture research, including the Green Revolution of the 1960s and the great advances that emerged then. Ironically that successful movement contributed to the current lack of available funding; as agriculture problems were solved and world food supplies outpaced demand, research money was directed elsewhere.

The article, part of a series on the world’s food production, includes a nice depth and breadth of information concerning agricultural research. Several photos and related links are included.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The issues described in the news article connect to the History and Nature of Science, Life Science, Science and Technology, and Science in Personal and Social Perspectives content standards of the National Science Education Standards. Here, we narrow our focus to the first two standards. However, this topic – world food supplies as related to agriculture and biotechnology – could easily serve as basis for an interdisciplinary unit in the middle grades.

Do any of the students have experience in growing vegetables? Ask students, what are some of the problems gardeners have to deal with in order to maintain their vegetables? What are some ways to deal with those problems? Help students to include the problem of insect pests in the discussion. Is it reasonable to assume that growers of crops on a large scale also have the same or similar problems? Can growers use the same approaches to deal with their problems that the gardener uses? Why or why not?

Ask students if they can identify one food plant, or crop, that is probably the world’s most common source of food. Consider keeping a list of all ideas and then asking the class to think carefully and critically when they answer these questions: What crop could probably be eliminated from the list, compared to the rest of the list? Why do they believe the food they are choosing to eliminate is probably not the world’s top food crop? You will hope that rice remains on the list!

Ask students to imagine that an insect has infested a large part of the world’s most important food crop. Consider putting the students in small groups in which they predict the consequences of an infestation. You might stipulate that they must have a clear prediction with logical justification for each domain: economy, culture, public health, government, military, and education. Next, ask them to articulate one or two questions that science could investigate in the hope of avoiding the consequences their group identified. For example, Which varieties of rice are most insect resistant? What other food crops can be grown in the areas where rice is currently grown? What nutritional substitutes should/could be distributed to areas where rice is in short supply? Students’ questions will vary widely and all are correct, as long as the questions can be subjected to scientific investigation and seem to point toward a solution to the stated problem.

Share with students the New York Times article, showing that such an event – insect infestation of an important crop – actually happened. Show them the pictures at the story’s web site. Inform them that the knowledge and technology necessary to prevent this disaster already exist. Ask students to speculate then on how this could have happened if people already know how to combat it. Lead them to understand the complexity of the history, funding, cultural values, and competition for funding as contributors to the situation. Finally, confirm and affirm the students’ predictions. They may have heard about food riots for example, in Africa and elsewhere. Ask them what direction they think governments and researchers should go next? Why?

As an extension, you could elaborate on the evolution aspect of the story: the way the bug has evolved through natural selection made possible by use of insecticides.

Here are additional resources from the National Science Digital Library Middle School Portal related to gardening, agriculture and natural selection: Thinking Green? Grow Your Own!; What Are Seed Banks and How Do They Work? and Dr. Saul’s Biology in Motion.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published May 21, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/19/12 by Jessica Fries-Gaither.

After 50 Years, Scientists Still Not Sure How DEET Works

DEET (short for N,N-diethyl-meta-toluamide) is the most widely used insect repellent in the world for a very good reason – it works really, really well! Just a quick spray on exposed skin keeps mosquitoes, flies, fleas, chiggers, and ticks away. Developed by scientists at the U.S. Department of Agriculture and patented by the U.S. Army in 1946, millions of people worldwide use DEET to ward off vector-borne diseases. First of all, why would researchers study DEET if it works so well? While DEET is an effective repellent, it doesn’t work against all bugs, it’s corrosive to plastics and there are concerns about its effect on human health.

 

Structural Formula for N, N-diethyl-meta-toluamide (DEET).
Courtesy of Wikipedia – Click on the image for a larger version.

How DEET actually works has puzzled scientists for more than 50 years. Scientists long surmised that DEET masks the smell of the host, or jams or corrupts the insect’s senses, interfering with its ability to locate a host. Mosquitoes and other blood-feeding insects find their hosts by body heat, skin odors, carbon dioxide (breath), or visual stimuli.

Amazingly, within a few months this year, scientists from two different labs have come up with competing explanations of how DEET works. In March of 2008, researchers at Rockefeller University in New York, said that DEET jams odorant receptors in insect nervous systems, in effect masking odors that would ordinarily attract the bugs. According to Dr. Leslie B. Vosshall, a researcher who worked on the project, now that they know that DEET targets OR83b co-receptors, they can quickly screen thousands of other compounds in hope of finding one that is even more effective and has fewer disadvantages.

Are you sure, ask researchers at the University of California, Davis? Mosquitoes flee because of their intense dislike for the smell of the chemical repellent and not because DEET jams their sense of smell. In August 2008, in a paper published in The Proceedings of the National Academy of Sciences, they provide a simpler explanation. Mosquitoes, they say, smell DEET directly and avoid it.

Dr. Vosshall, involved in the earlier study, said that her team stood by its work, and that its findings were based on a variety of experiments. So for now, the jury is still out.

Connecting to the National Science Education Standards

These competing explanations on how DEET works provides a perfect example of one aspect of the nature of science – Scientific Claims are Subject to Peer Review and Replication. Researchers in labs across the world work on answering many of the same questions. The results of their work are published in peer reviewed journals so that researchers around the world can examine their data and logic, identify alternative explanations, and replicate observations and experiments. Peer review is an integral part of genuine scientific enterprise and goes on continuously in all areas of science.

The National Science Education Standards in the History and Nature of Science Content Standard G describes what middle school students should understand about this part of the nature of science, including:

It is normal for scientists to differ with one another about the interpretation of the evidence or theory being considered.

Different scientists might publish conflicting experimental results or might draw different conclusions from the same data.

It is part of scientific inquiry to evaluate the results of scientific investigations, experiments, observations, theoretical models, and the explanations proposed by other scientists.

Although scientists may disagree about explanations of phenomena, about interpretations of data, or about the value of rival theories, they do agree that questioning, response to criticism, and open communication are integral to the process of science.

Additional Resources

Read the entire National Science Education Standards online for free or register to download the free PDF. The content standards are found in Chapter 6.

Science For All Americans Online: The Nature of Science
Science for All Americans consists of a set of recommendations on what understandings and ways of thinking are essential for all citizens in a world shaped by science and technology.

Household Product Database
List of products that contain DEET.

Chemical Technical Summary for Public Health and Public Safety Professionals
The Department of Health and Human Services provides a summary of all medical cases and research done on DEET.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Kimberly Lightle and published August 26, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/19/12 by Jessica Fries-Gaither.