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Activity Seven
Beetle Collection and Release
Objectives
Students
will observe and investigate natural enemies of indigenous wetland plants
or on-site indigenous school plants and compare them to the observable
enemies of purple loose strife. This activity may be done as a field
observation, hands-on classroom activity or research activity. Students
will then release Galerucella beetles (a purple loosestrife natural
enemy) in a local loosestrife infested area.
State Science Curriculum Objectives
Constructing objectives: 13,
14, 15
Reflecting objectives: 11,
13, 15
Using objectives LEC: 6,
7, 15, 16, 18
Methods
Students will locate an infested wetland
for on-site purple loosestrife and indigenous plant herbivory observation
and/or teacher/student will bring in samples of loose strife and indigenous
plants to classroom for observation. Students will either shake down
the plants for possible natural enemies and/or record signs of herbivory
in the classroom and compare the natural enemies of indigenous plants
to local purple loose strife. Students will then predict possible impacts
on plant populations based on observed evidence. After learning about
the purple loosestrife project and Galerucella beetles, students
will release these natural enemies in the wetland area.
Terms
Herbivory,
predators, indigenous and nonindigenous species.
Background
Ecosystems evolve a balance between
their many species. Predation is a part of that natural balance. Indigenous
plant and animal populations are kept in check by indigenous predators.
Invading species threaten ecosystems because invaders frequently do
not have predators. The invaders often have the ability to disrupt the
existing ecological balance, dominate an area and have adverse unforeseen
consequences. Purple loosestrife is an invading species with few if
any local natural predators.The USDA has approved theGalerucella
beetle, a natural predator from Europe for use in Purple loosestrife
control. Section Two of the Cooperator's Handbook provides details
on the biology, ecology and management of these two organisms, and includes
additional references for teachers and students. See: About field collection of Galerucella.
Materials
White
bedsheets, scissors or plant clippers, small sealable plastic bags,
and large plastic bags, tweezers, magnifying glasses, insect identification
books, microscopes (dissection, field or Brock optical scopes), and a wetland location with purple loosestrife.
Procedure
- Locate a site with a fairly large, medium
to heavy infestation of purple loosestrife. (Much of this activity
can still be done if a site with just a few loosestrife is the only
available site.) Arrange a field trip to the site. Obtain permission to enter the site.
- While on site, students individually or in
groups of two, map and record site observations such as surrounding
human activity, plant and animal life, water amount and flow etc.
Students draw map noting surrounding roads and locating observed plants
and animals water etc. On map note, time of day, year and weather
observations. This may impact findings.
- Divide students into groups of 3-4 for collection.
To collect data in the field, students choose several indigenous plants
on the site to compare to the purple loosestrife found there. Sit
or stand quietly and observe the plants for visitors that might be
feeding. Record any observed insects or birds feeding on the plants.
Collect predator data by shaking the plants over a sheet and putting
contents of sheet into individually marked small sealable bags for
later identification. Using the same plants record the observable
signs of herbivory, holes and chewing on leaves, and stems. Use the
same number of each plant and randomly observe the same number of
leaves and stems for herbivory on each plant. Cut a sample or two
of each plant to bring back to the classroom for further observation.
To do data collection solely in the classroom, samples must be cut
in the field and brought into the classroom for herbivory observation.
Each specimen should be carefully bagged in the field to preserve
any resident feeding insects. Each plant should be cut off at ground
level.
- In the class room observe, identify and record
different kinds and numbers of organisms found on the plants, including
fungus. Using identification books try to identify organisms associated
with the plant. Covering the desks or tables with sheets of white
paper facilitates observation. Observe and record signs of herbivory
on selected leaves and stems. The book Eco Inquiry, published
by Kendall Hunt, is recommended for graphic examples of herbivory,
in addition to the materials found in Section Two of theHandbook.
Chart and compare data. Is there any difference between predation
on indigenous plants and on the purple loose strife? Student may also
do print material or internet research on their chosen plants about
possible predators and other limits to growth.
- Present group findings to class with predictions
for future population growth of the chosen plants compared to the
purple loose strife based on data collected.
- Read and discuss the use of Galerucella
beetles as predators for purple loosestrife control.
- Keep a running biannual observation log (spring
and fall) of the beetle release site and
how the herbivory relationship between purple loosestrife and other
indigenous plants changes over time. This activity will become richer
over the years. The same herbivory observation can be done year after
year in the same place. It should be interesting to trace the impact
of the beetles on the purple loosestrife and observe if the beetles
impact any other plants in the area.
Extensions
A
practice trial of this activity could be done with any plants in your
local school yard.
Students of different school districts could provide information
to the Purple Loosestrife Project office, using input forms provided.
See the Purple Pages Fall and Spring forms or contact
the project office for details.
Evaluation
Evaluation
could be based on observation of students careful methodology with data
collection, written record of observations and communication to class
of predictions.
Activities: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10
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