Role of Cerci in Escape Responses of the Cockroach

Shelia Smith

Gail Knox

Overview

Escape reactions are very useful in analyzing animal behavior. The cockroach has one of the best understood escape systems. The escape system of the cockroach illustrates a reasonably complex neural circuitry, making it a useful neurological model. In this activity, students will investigate the role of cerci in escape responses of the cockroach. The absence or presence of cerci in roaches will be used to relate wind stimuli to motor activity.

Biological Concepts

• Escape Behavior

• Action Potential

• Sensory Neurons

• Motor Neurons

• Interneurons

• Synapse

• Axon

Class Time

This activity will require approximately 55 minutes for a high school general biology class.

Background Information

One important aspect in behavioral neurobiology is to understand how animals respond to stimuli such as food or an aversive stimulus such as a predator. The escape system of the cockroach has become an important system for studying escape behavior. The cockroach responds to wind stimuli with an escape response that begins with a rapid turn that points itself away from the source of wind stimulus. The wind puffs deflects hairs on the cerci, two antennae like appendages on the rear. Each hair has a preferred direction of deflection and is innervated by an afferent neuron whose axon is located in one of the cercal nerves. Sensory neurons that enervate the cercal hairs project to the terminal ganglion, where they synapse directly with interneurons. Populations of neurons, going from sensory structures, through interneurons, to motor neurons, have been identified and established as a basic circuit for evoking initial turns. The primary stimulus that elicits the escape turn is wind, generated by a predator’s lunge.

Materials

• Madagascar Hissing Cockroaches

• Plastic containers

• Platform (cork or cardboard)

• Pins

• Scissors

• Roach habitat

• Vaseline

• Wood chips

• Egg cartons

• Paper towels

• Gravel, pine shavings or sawdust

• Dog food

• Fresh fruit and vegetables

• Water

• Sponge

• Latex gloves

• Pipettes

• Drill or screwdriver

Teacher Preparation

1. Housing cockroaches in captivity pose two main problems: the temperature must be

kept at least 25 degrees Celsius and a secure habitat to prevent escape.

2. A clear shoe box can be used for a pair of roaches. Punch a few holes in the box to

provide air. If the lid is not very tight-fitting and secure, tape the lid shut around the

edges. A ten gallon aquarium can be used to house large quantities of cockroaches.

The inside rim of the tank should be smeared with a 2 inch wide band of vaseline to

prevent escape. A cockroach habitat can be purchased from Carolina Biological

Supply House.

3. Wood chips and half an egg carton or cardboard roll from paper towels provide hiding

spots. Use gravel, pine shavings, or sawdust to line the bottom of the cage.

4. Feed the cockroaches dry dog food with pieces of fresh fruit and vegetables. Provide

water with a damp sponge in a small cup or dish.

5. When handling a Madagascar roach, pick up the insect very gently around the thorax

(the hard section behind the small head). Be careful not to jerk, since the feet have

sticky pads and hooks that grip tightly.

6. Drill holes into the plastic containers at 45, 60, and 90 degree angles. The holes

should be the size of the pipette or any instrument used for wind stimuli.

7. The winds puffs are generated by inserting the pipette into the holes of the plastic

containers.

Extensions/Variations

1. Students can design an experiment to measure the distance turned after applying a

wind stimulus.

2. Students can design an experiment to test other types of stimuli on the cerci.

3. Students can design an experiment to test other sensory receptors of the cockroach.

NAME:___________________________ DATE: ______________ PERIOD: __________________

STUDENT DATA SHEET

Pre-Lab Discussion

Escape reactions are very useful in analyzing animal behavior. The cockroach has one of the best understood escape systems. The escape system of the cockroach illustrates a reasonably complex neural circuitry, making it a useful neurological model. In this activity, you will investigate the role of cerci in escape responses of the cockroach. The

absence or presence of cerci in roaches will be useful to relate wind stimuli to motor activity.

1. Obtain the following supplies from the teacher:

plastic container

platform (cork or cardboard)

pins

scissors

latex gloves

pipette

cockroach

2. Place a cockroach in the plastic container and observe its’ behavior for a few minutes.

Use the pipette to generate wind puffs at various angles (45, 60, and 90 degrees).

Observe and record the movements of the cockroach in your data table. This is your

control.

3. Pin the cockroach dorsal-side up to the platform and remove one cercus. Remove the

pin and use the pipette to generate wind puffs at various angles (45, 60, 90 degrees).

Observe and record the movements in your data table.

4. Pin the roach dorsal-side up to the platform and remove the other cercus. Remove the

pin and use the pipette to generate wind puffs at various angles (45, 60, and 90

degrees). Observe and record the movements of the cockroach in your data table.

DATA TABLE

Analysis and Conclusions

1. Was the directional response the same from each angle?

2. Did the cockroach respond differently to wind puffs produced at different angles?

3. Write a lab report describing the results of your investigation.

Resources

Cambi, J. M. and Levy, A. Fixed and variable components of the cockroach escape behavior. Journal of Comparative Physiology, Vol. 163, pp. 317-328 1988.

Darmo, L. and Ludwig , F. Madagascar Giant Hissing Roaches. Carolina Biological Supply Company.

Ritzman, W. and Goddard, D. Wind-activated thoracic interneurons of the cockroach. Journal of Neurology, Vol. 19. No.7, pp.573-588, 1988.

Acknowledgment

Many thanks to Dr. Charles Drewes of Iowa State University and Mary Colvard

of Cobleskill, New York (Access Excellence).

About The Authors

Sheila Smith is a biology teacher at Byram High School in Jackson, MS.

She can be contacted by e-mail at ssmith54@aol.com.

Gail Knox is a biology teacher at South Pike High School in Magnolia, MS.

She can be contacted by phone at 601-783-2312.

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