Behavioural responses of Periplaneta americana to red,

blue, green and white light colours

Lindsay Grant, Ashley Mah and Gillian TetlowBIOL 3401

Mount Allison University

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

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

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

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?

Hypothesis

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

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

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

Peripheral and Centre Lines

Peripheral boxesCenter boxesStart Area

Results

• Peripheral 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

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.

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.

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

Wiedenmann 1977

Koehler et al. 1987

• red light appears the same as dark light

• gold and red light cause less activity in German cockroaches

White and Red Light

• peripheral line crossings occurred the lest

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

Future Implications

• Exhibit more movement in dark light conditions

• Direct influences of red and white light

References• Adiyodi, K. G. 1981. The American Cockroach.1st edn. Netherlands: Springer.

• Harker, J. E. 1956. Factors controlling the diurnal rhythm of activity of Periplaneta americana L. Journal of Experimental Biology. 33: 224-34.

• Koehler, P. G., Agee, H. R., Leppla, N. C. and Patterson, R. S. 1987. Spectralsensitivity and behavioral response to light quality in the German cockroach (Dictyoptera blattellidae). Annals of the Entomological Society of America. 80: 820-822.

• Walther, J.B. 1958. Charges induced in spectral sensitivity and form of retinal action potential of the cockroach eye by selective adaptation. Journal of Insect Physiology. 2: 142-151.

• Wiedenmann, G. 1977. Activity peaks in the circadian rhythm of the cockroach(Leucophaea maderae). Journal of interdisciplinary cycle research. 8: 378-383.

• Image of eye diagram: http://www.gwu.edu/~darwin/BiSc151/Ecdy/Ecdysozoa.html

• Walther, J. B. 1958. Changes induced in spectral sensitivity and form of retinal action poterntial of the cockroach eye by selection adaptation. Journal of Insect Physiology. 2: 142-151.

Questions?