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Ch. 54 - Biodiversity and Conservation Ecology
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
Chapter 54, Problem 13

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over \$100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations.
Look at the graph. Why did the researchers bother to collect data from the coffee shrubs before adding the nets to treatment plots to exclude birds?

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The researchers collected data from the coffee shrubs before adding the nets to establish a baseline measurement of the percentage of berries with borers in both control and treatment plots.
By having baseline data, researchers can compare the percentage of berries with borers before and after the nets are installed, allowing them to assess the impact of bird exclusion on borer infestation.
The graph shows that before the nets were installed, the percentage of berries with borers was similar in both control and treatment plots, indicating that any differences observed after net installation can be attributed to the exclusion of birds.
After the nets were installed, the treatment plots (where birds were excluded) showed a significant increase in the percentage of berries with borers compared to the control plots, suggesting that birds play a role in controlling borer populations.
Collecting data before the intervention helps to ensure that any observed changes in borer infestation are due to the experimental treatment (bird exclusion) rather than pre-existing differences between the plots.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Coffee Berry Borer Beetle

The coffee berry borer beetle, scientifically known as Hypothenemus hampeii, is a significant pest affecting coffee crops. It burrows into coffee berries, leading to substantial crop loss, sometimes up to 50%. Understanding its life cycle and behavior is crucial for developing effective pest management strategies in coffee farming.
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Exclusion Nets

Exclusion nets are physical barriers used in agriculture to protect crops from pests, particularly birds and insects. In the context of the study, these nets were installed to determine their effectiveness in reducing the percentage of coffee berries infested by the coffee berry borer beetle. Analyzing data before and after net installation helps assess their impact on pest populations.
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Control vs. Treatment Plots

In experimental research, control plots are used as a baseline to compare against treatment plots, which receive the experimental intervention—in this case, the exclusion nets. By collecting data from both types of plots, researchers can evaluate the effectiveness of the intervention in reducing pest infestation and understand the dynamics of pest populations in relation to environmental factors.
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Related Practice
Textbook Question

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over \$100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations.

Based on what you have learned in this chapter about global trends in terrestrial ecosystems, what is currently the largest threat to the wet tropical forests in Central America?

a. Habitat destruction, such as the clearing of forests for coffee plantations

b. Exotic species, such as the introduction of coffee berry borers

c. Pollution, such as the use of pesticides in coffee plantations

d. Climate change, such as changes in precipitation patterns

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Textbook Question

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over \$100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations.

Pesticides are generally ineffective in killing coffee berry borers. Ecologist Daniel Karp and colleagues conducted a study in Costa Rica to determine if natural predators like birds reduce the beetle population. The researchers selected 12 control plots and used nets to exclude birds from 12 similar treatment plots. What is the take-home message of the graph? (Remember, * means P < 6 0.05)

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Textbook Question

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over \$100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations. The abundance of birds and other predators of borer beetles depends on how much natural forest is left within and around the coffee plantations. What is the approximate percentage increase in borer predators per hectare if forest cover is doubled from 15 to 30 percent?

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Textbook Question

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over \$100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations. Draw a simple model to compare the relative species richness and species diversity of these two coffee plantations: one is clear-cut and planted with only coffee shrubs, the other retains some natural forest. For symbols, use a few letters to represent different species of plants and a few numbers to represent different species of animals in a square 1-ha plot.

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