Illinois Natural History Survey Reports

              1
R e p o r t s
March/
April 1996
No. 338
I N S I D E
Land Managed for
Waterfowl in the Il-linois
and Mississippi
Floodplains
2
Indiana Bats in
Illinois
3
Effects of Electrofi shing
on Sunfi sh
4
Species Spotlight:
Beavers
6
The Naturalist's
Apprentice:
What's a Beaver To Do?
7
Children Conduct Biological Control
Research
Fourth graders weigh gypsy moth
larvae to determine if microsporid-ian
disease affects weight gain.
Continued on back page
I LLINOIS
NATURAL
HI STORY
S U R V E Y
Photo by Lee Solter, INHS Center for Economic
The gypsy moths (Lymantria
dispar) that are found in the
United States originated in
Europe. They were brought
to North America in 1868 by
Leopold Trouvelot, an amateur
entomologist and astronomer,
who planned to use them to
produce silk. The moths escaped
from his house in Medford,
Massachusetts, then multi-plied
and began killing trees.
Today, gypsy moths are found
mainly in the northeastern states
but they can also be found in
Michigan, Ohio, Virginia, and
sometimes Illinois.
The favorite foods of gypsy
moth larvae are the leaves of
oak, willow, aspen, and birch,
but they will eat the leaves of
many other trees. Gypsy moths
have become serious pests in
the forests of North America.
Pesticides can be used
to decrease the gypsy
moth populations but
pesticides may kill
other harmless insects.
Some scientists are
focusing on the use of
natural predators and
pathogens to decrease
the populations of
gypsy moths. Some
entomologists are
testing microsporidia,
a protozoan pathogen
group, as a weapon
against the gypsy
moth.
Our fourth grade class
at Leal School in Ur-bana,
IL, was invited to perform
an experiment with one kind of
microsporidium that was found in
gypsy moths in Slovakia but does
not occur in gypsy moths in North
America. We agreed to help. First,
we visited the laboratory to learn
about what we would be doing.
We were going to help with an
experiment to study microspo-ridia.
Each week, a group of
three or four students went to the
laboratory to perform part of the
experiment.
For each of 7 trials, 10 gypsy
moth larvae were fed micro-sporidian
spores in 1 ml of
water from a metal loop and 10
additional larvae were fed 1 ml
of water without spores. We then
weighed each larva by picking it
up with forceps and placing it on
a sensitive scale. We recorded the
weights on data sheets and used a
calculator to average the weights
of the control larvae and the
infected larvae. We learned that
there should always be a control
group in an experiment to com-pare
with the infected group.
After weighing, we placed the
larvae in plastic cups with food
in them, one larva per cup. These
were kept in growth chambers.
The larvae were weighed again
7 and 14 days later. Forty-fi ve
days after treatment, the develop-mental
stage of each insect was
recorded and they were dissected
to make sure that larvae fed
spores were infected and larvae
fed water were uninfected.
The difference between the
average weights of the infected
and control groups of larvae was
insignifi cant at the beginning of
the experiment. For six of the
seven groups, the average ending
weight of the infected larvae was
less than that of the controls. We
also found that more individu-als
in the control group went to
Colleen Brodie and Shameem Ra-kha,
teachers at Leal Elementary
School in Urbana, IL, and Lee
Solter, research scientist at the Il-linois
Natural History Survey, had
several objectives for a research
project for fourth graders:
• Conduct original research in a
scientifi c laboratory
• Use the scientifi c method, in-cluding
hypothesis testing and
controlled experimentation
• Practically apply mathematics
and data analysis
• Publish results in a scientifi c
newsletter
• Integrate project into classroom
curriculum