1. Behavioural responses of Periplaneta americana to red, blue, green and white light colours
Lindsay Grant, Ashley Mah and Gillian Tetlow
BIOL 3401
Mount Allison University

2. The American Cockroach
Not endemic to America
Natural habitat:
Mainly found in dark, damp areas
In populated areas they often live in basements
Have very quick reflexes

3. The Compound Eye Sensitive to light levels and specific colours
Composed of:
Ommatidia
An optical system
Photoreceptor cells
Within the optical system there are variants for nocturnal animals
Superimposed eyes or apposition eyes

4. Sensitive to Wavelengths
Walther (1958)
Examined the spectral sensitivity and the action potential of the compound eye
The peak sensitivity curve occurred in ultraviolet lights
Results showed the compound eye has the ability to discriminate colours

5. Goal of Study
Determine if movement is influenced by different light colors
Observe general behaviours:
Was the cockroach sprinting around the tank or calmly moving?
Was there centre line avoidance under certain light colors?

6. Hypothesis
Cockroaches will show the greatest movement and no centre line avoidance in blue and green lighting.

7. Methods Experimental environment: dark, warm room
Experiment conducted in a small rectangular fish tank
Transect lines drawn 3x6 with a 2 cm starting space
A 40watt spotlight placed above the tank
Light conditions: normal white, blue, green, and red

8. Collecting Data 5 trials for each condition
2 minute acclimation then moved to starting space
Observation period of 3 minutes to count peripheral and centre line crossing

9. Peripheral and Centre Lines
Peripheral boxes
Center boxes
Start Area

10. Results Peripheral line crossing: Centre line crossing
Highest - Green light, 75 lines
Lowest - Red light, 41.4 lines
Centre line crossing
Highest - Green light, 4.8 lines
Lowest - Normal white light, 2.4 lines

11. Figure 1. Mean (±SE) number of peripheral line crossings of cockroaches (Periplaneta americana) in four light conditions (n=5): blue, red, green, and normal white. Lines were drawn 6x3 (L x W) in a boarded rectangular fish tank and observations occurred for 3 minutes following a 2-minute acclimation period.

12. Figure 2. Mean (±SE) number of centre line crossings of cockroaches (Periplaneta americana) in four light conditions (n=5): blue, red, green, and normal white. Lines were drawn 6x3 (L x W) in a boarded rectangular fish tank and observations occurred for 3 minutes following a 2-minute acclimation period. The centre lines consisted of the middle row.

13. Blue and Green Light
Perceive colour in the blue-green range of the visible light spectrum
Walther 1958
True colour vision
Blue green light is the same as dark stimulation
More line crosses
Harker 1955
Circadian rhythms

14. White and Red Light peripheral line crossings occurred the lest
Wiedenmann 1977
red light appears the same as dark light
Koehler et al. 1987
gold and red light cause less activity in German cockroaches

15. Light Exposure Adiyodi 1981 Increase activity unless able to retreat
Most intense light at the centre of the tank
The cockroaches stayed on the periphery

16. Future Implications Exhibit more movement in dark light conditions
Direct influences of red and white light

17. References
Adiyodi, K. G The American Cockroach.1st edn. Netherlands: Springer.
Harker, J. E Factors controlling the diurnal rhythm of activity of Periplaneta americana L. Journal of Experimental Biology. 33:
Koehler, P. G., Agee, H. R., Leppla, N. C. and Patterson, R. S Spectralsensitivity and behavioral response to light quality in the German cockroach (Dictyoptera blattellidae). Annals of the Entomological Society of America. 80:     
Walther, J.B Charges induced in spectral sensitivity and form of retinal action potential of the cockroach eye by selective adaptation. Journal of Insect Physiology. 2:
Wiedenmann, G Activity peaks in the circadian rhythm of the cockroach(Leucophaea maderae). Journal of interdisciplinary cycle research. 8:
Image of eye diagram:
Walther, J. B Changes induced in spectral sensitivity and form of retinal action poterntial of the cockroach eye by selection adaptation. Journal of Insect Physiology. 2:

18. Questions?