This activity engages students to better understand the impact of transmission by invasive species. Using dice, poker chips, and paper plates, an entire class mimics the spread of an invasive species within a geographic region. The activity can be modified and conducted at the K–16 levels.

An invasive species is defined as a “non-native species whose introduction does or is likely to cause economic or environmental harm or harm to human, animal, or plant health” (Invasive Species Advisory Committee, 2006). An invasive species can be a microorganism (i.e., virus or bacterium), animal, or plant. For example, the lionfish, naturally found in the Western Pacific Ocean, is now seen in increasing numbers in the Caribbean (National Ocean Service, 2012). Because it is a voracious eater, scientists worry about the lionfish’s presence disrupting an already fragile reef ecosystem.

The study of an invasive species in a classroom setting has many advantages. (1) It meets many core ideas presented in the new K–12 Frameworks provided by the National Academies (National Research Council, 2012). Table 1 provides ideas as to where this study fits the Life Science core ideas. (2) This is an opportunity to introduce various species from viruses (acellular) to plants and animals. (3) Discussion of invasive species provides a context for introducing core ideas, which helps students relate to the material, especially if the invasive species invades your home environment. (4) It engages and makes students aware of current scientific issues. (5) Many different disciplines, including history, ethics, economics, and geography, can be intertwined in the study of invasive species. (6) The addition of a hands-on activity provides alternative and engaging learning practices.

Table 1.

Core ideas in the life sciences addressed by this activity.

From Molecules to Organisms; Structures & Processes:
• Describe the life cycle of an invasive species. 
Ecosystems, Interactions, Energy & Dynamics: 
• Describe how an invasive species affects an ecosystem.
• Explain the interdependent relationships in an ecosystem. 
Biological Evolution: Unity & Diversity: 
•Explain how humans can affect the diversity of living organisms.
•Explain how an invasive species can influence natural selection by other species. 
From Molecules to Organisms; Structures & Processes:
• Describe the life cycle of an invasive species. 
Ecosystems, Interactions, Energy & Dynamics: 
• Describe how an invasive species affects an ecosystem.
• Explain the interdependent relationships in an ecosystem. 
Biological Evolution: Unity & Diversity: 
•Explain how humans can affect the diversity of living organisms.
•Explain how an invasive species can influence natural selection by other species. 

The following activity can be used at any K–16 level, depending on the depth of discussion and analysis. The emerald ash borer (EAB), a beetle whose life cycle harms and kills ash trees, is our model invasive species.

Invasive Species Activity Preparation

  • Pick an invasive species. Identify background information and resources for students. Materials presented here will need to be modified if not using EAB.

  • Materials: one six-sided die for each student in the classroom, poker chips (or other plastic chips), and paper plates or trays.

  • The activity takes approximately 15 minutes. Additional time for introduction and analysis may be desired.

Procedure for Student Engagement

Step 1: Introduce the Ecosystem That May Be Harmed

One short and useful hands-on activity to introduce the species and their relationships in an ecosystem is to construct a food web. I used an ecosystem that contained ash trees and could be invaded by EABs. I listed the following organisms and asked the group to draw how they are connected: snake, deer, tree, mouse, caterpillar, grass, sun, hawk, squirrel, cougar, and microorganisms. As a result, the following was identified: (1) living species depend on and interact with each other, (2) a food web is not really a chain, and (3) each group was creative and drew different representations (which is okay!). This exercise set the stage to later discuss the impact of EAB on this ecosystem. Older students could organize the web into its trophic levels and discuss the energy flow within the web.

Step 2: What Is EAB?

The invasive species and its characteristics are introduced. To understand EAB transmission, it is helpful to understand its life cycle. As an example of an activity, each step of the EAB life cycle was placed on a card (a picture of EAB at each stage and a description; adopted with permission from http://www.emeraldashborer.info/lifecycle.cfm). I asked students to place the cards in the order of the EAB life cycle.

Step 3: What Does the EAB Do to Ash Trees?

As eggs hatch in the ash tree’s bark, EAB larvae develop and feed on the inner bark. This disruption interrupts water flow and nutrients in the tree, ultimately killing it. Signs of infestation include foliage loss, shoots sprouting at the base, and S-shaped patterns (movements of larvae) in the bark. One predator for the EAB larvae is the woodpecker.

Step 4: How Does EAB Spread? Setting Up the Activity

This activity is developed to engage and help students measure the transmission of EAB. To prepare the activity, I used historical transmission data for EAB (Table 2; http://www.emeraldashborer.info). Using real data may help students find relevance to the activity. Briefly, EAB is native to Asia and can fly and move to nearby ash trees to meet their nutrient requirements. In addition, EABs move farther distances through human behavior. Ash logs are used for firewood, shipping crates, or even furniture. When these materials are moved to more distant locations, EAB embeds in the logs and transmits with them. This is believed to be the cause of EAB transmission from Asia to North America.

Table 2.

Transmission of the emerald ash borer (EAB; see http://www.emeraldashborer.info/index.cfm).

Year of EAB DetectionRegion of DetectionNumber of Ash Trees on Timberlanda
Previous to 2002 Asia (eastern parts and China)  
2002 Michigan and Ontario MI: 692,900,000 
2003 Ohio 279,400,000 
2004 Indiana 146,900,000 
2006 Illinois and Maryland IL: 131,300,000 
2007 West Virginia and Pennsylvania WV: 150,400,000; PA: 299,700,000 
2008 Wisconsin, Missouri, and Virginia WI: 628,100,000; MO: 213,400,000; VA: 169,100,000 
2009 Minnesota, New York, and Kentucky MN: 692,900,000; NY: 767,300,000; KY: 291,600,000 
2010 Tennessee and Iowa TN: 261,600,000; IA: 33,000,000 
2012 Connecticut CT: 22,400,000 
Year of EAB DetectionRegion of DetectionNumber of Ash Trees on Timberlanda
Previous to 2002 Asia (eastern parts and China)  
2002 Michigan and Ontario MI: 692,900,000 
2003 Ohio 279,400,000 
2004 Indiana 146,900,000 
2006 Illinois and Maryland IL: 131,300,000 
2007 West Virginia and Pennsylvania WV: 150,400,000; PA: 299,700,000 
2008 Wisconsin, Missouri, and Virginia WI: 628,100,000; MO: 213,400,000; VA: 169,100,000 
2009 Minnesota, New York, and Kentucky MN: 692,900,000; NY: 767,300,000; KY: 291,600,000 
2010 Tennessee and Iowa TN: 261,600,000; IA: 33,000,000 
2012 Connecticut CT: 22,400,000 

aPotential for infestation (Nowak et al., 2003).

As seen in Table 3, to mimic transmission, paper plates (representing distinct geographic regions) are placed throughout a classroom. I identified three regions/spaces in the classroom based on the timing of EAB spread. Region 1 represents Asia, the starting point for the activity. Region 2 (placed closer to Region 1) represents locations where spread first originated (i.e., Michigan, Ontario, Indiana, and Illinois). Region 3 (placed farther away from Region 1) represents farther and later spread (Wisconsin, Minnesota, Iowa, Virginia, and Missouri). Poker chips are placed on each paper plate to represent the ash trees in each region (Figure 1). Each student represents an EAB and obtains a die. Every roll of the die represents an EAB life cycle; based on the number rolled, students use the key to determine the outcome for EAB (Table 4). In some cases EAB spreads only locally, but in other cases EAB spreads via human behavior.

Figure 1.

Poker chips representing ash trees. Colors indicate different regions.

Figure 1.

Poker chips representing ash trees. Colors indicate different regions.

Table 3.

Transmission activity set-up.

ModelRepresentationClass of 20 Students
Dice Emerald ash borer (EAB); each student takes one die; each roll represents one life cycle (1 year) 20 dice 
Poker chips Ash tree; chips are placed in each geographic region (paper plate); when the ash tree dies, it is removed from the plate 40 chips in native region; 20 chips in other regions 
Paper plates Geographic region; each region represents locations of EAB spread 10 plates (regions) 
ModelRepresentationClass of 20 Students
Dice Emerald ash borer (EAB); each student takes one die; each roll represents one life cycle (1 year) 20 dice 
Poker chips Ash tree; chips are placed in each geographic region (paper plate); when the ash tree dies, it is removed from the plate 40 chips in native region; 20 chips in other regions 
Paper plates Geographic region; each region represents locations of EAB spread 10 plates (regions) 
Table 4.

Dice key: results of one emerald ash borer (EAB) life cycle.

Number rolled:What will EAB (you) do?
You are happy in this community and stay in the region. You killed one ash tree and move to a neighboring ash tree (remove a poker chip). 
You are happy in this community and stay in the region. You killed one ash tree and move to a neighboring ash tree (remove a poker chip). 
Oh no! A woodpecker has found you in the bark. You are eaten and will not survive. You did not kill the ash tree (do NOT remove a poker chip). Stop playing. 
The ash tree you are living on is chopped down and used as campfire and crate material. Your tree is dead; remove a poker chip in your original home and move to a new location of your choice. 
The ash tree you are living on is chopped down and used as campfire and crate material. Your tree is dead; remove a poker chip in your original home and move to a new location of your choice. 
You killed an ash tree (remove a poker chip) but move to a different community in close proximity (this could be in a neighboring state). 
Number rolled:What will EAB (you) do?
You are happy in this community and stay in the region. You killed one ash tree and move to a neighboring ash tree (remove a poker chip). 
You are happy in this community and stay in the region. You killed one ash tree and move to a neighboring ash tree (remove a poker chip). 
Oh no! A woodpecker has found you in the bark. You are eaten and will not survive. You did not kill the ash tree (do NOT remove a poker chip). Stop playing. 
The ash tree you are living on is chopped down and used as campfire and crate material. Your tree is dead; remove a poker chip in your original home and move to a new location of your choice. 
The ash tree you are living on is chopped down and used as campfire and crate material. Your tree is dead; remove a poker chip in your original home and move to a new location of your choice. 
You killed an ash tree (remove a poker chip) but move to a different community in close proximity (this could be in a neighboring state). 

Conduct the Activity

Each student starts their life cycle in Asia. Their goal as an EAB is to survive and find additional nutrients (ash trees) for their life cycle. Five students roll their dice. Depending on the number they roll, they follow the key (Table 4). If they are killed by a woodpecker, they stop the game. If they survive and reproduce, they add another EAB (i.e., another student) who will now roll their dice. This mimics the replication process and keeps students who “die” to continue participation in the activity as a new EAB larvae. If they killed a tree, they remove a poker chip from the paper plate. They may hang on to these chips. Please remember, EABs cannot fly long distances – only within the state and into neighboring states. This means that they cannot fly across oceans (all the way from Asia to the United States) or to nonbordering states without human help (rolling a 4 or 5). To better mimic the transmission, after leaving Asia, students must first move to Region 1. Then, when in Region 1, they can spread to Region 2, depending on their roll.

Once all of the EABs have died, the activity ends. There are several means for analysis:

  • Count the number of ash trees left in each region. Averages for regions and graphs can be constructed to measure the change in ash populations.

  • Students can count their collected poker chips (the number of ash trees they killed). You will likely notice some variability in numbers, which exemplifies the variation in a living species’ life cycle.

  • Students can compare the number of ash trees lost in Asia, Region 1, and Region 2. What do these numbers suggest regarding the spread of EAB? Students could use percentages tabulated in the activity to predict the spread of EAB and the death of ash trees using the real data provided in Table 2.

After analysis, I ask students to return to the food web and add EAB. This helps stress the impact that EAB has not only on trees but on entire ecosystems. Some questions that might be addressed by students, particularly at the older grade level, include (1) At what trophic level does the invasive species exist? (2) Which species occupy the same niche as the invasive species? (3) How are energy levels and the food web disrupted by the invasive species? (4) This activity represents a model of invasive species’ spread. How is this model accurate, and what is problematic about it? For example, a large tree infested by EAB is often killed in 2–3 years, not exemplified in this model.

Discussion & Modifications

This activity gives the teacher flexibility to meet core ideas in the life sciences and address any grade level, and it can be modified as follows:

  • You can use different invasive species and modify the key. For example, if using

  • a microorganism that causes disease in humans, means of transmission might be through human interaction. Microorganisms might be “killed” via antimicrobial agents.

  • You can control the rate of transmission of your invasive species by how many numbers on the dice represent that means of transmission. For example, before preventive mechanisms for EAB transmission were established, the movement of EAB from state to state via human behavior was higher. This is represented by two numbers on the dice (as shown in Table 4). However, as preventive measures are established (i.e., pesticides), one number on the dice might be switched from a “transmission” outcome to death of EAB. A wonderful learning opportunity is to play the game before preventive measures were in place, then again after measures are taken (modify the key). The results will be substantially different.

  • You can control the replication level. An EAB can lay 1 to 23 larvae per replication cycle. Commonly one egg is laid, and this is mimicked in the activity. However, one could increase the replication numbers by adding more than one student for each student who rolls the die and successfully replicates.

  • Interdisciplinary topics can be expanded during the activity. Discussions on epidemiology, public health, ethical issues, geography, public policy, and economics may be included.

Additional Resources

References

References
Invasive Species Advisory Committee. (2006). Invasive Species Definition Clarification and Guidance White Paper. Available online at http://www.invasivespeciesinfo.gov/docs/council/isacdef.pdf.
National Ocean Service. (2012). Invasive lionfish. Available online at http://www.ccfhr.noaa.gov/stressors/lionfish.aspx.
National Research Council. (2012). A Framework for K–12 Science Education: Practices, Crosscutting Concepts, and Core Ideas. Washington, D.C.: National Academies Press.
Nowak, D., Crane, D., Stevens, J. & Walton, J. (2003). Potential damage from emerald ash borer. USDA Forest Service Northern Research Station. Available online at http://nrs.fs.fed.us/disturbance/invasive_species/eab/local-resources/downloads/EAB_potential.pdf.