LIFE CYCLE OF Pieris Rapae
- Practice student directed investigation.
- Explore factors influencing animal behavior.
- Gain experience in analysis and presentation of data.
is the sum of the
responses of an organism to internal and external stimuli. Ethology
is the study of animal behavior in the context of evolution, ecology,
organization, and sensory abilities of an animal. There are two basic
categories of behavior: learned and innate (inherited) behavior.
evidence suggests that the basis
of both lies in the interaction between the animal’s genes and it's
environment. This interaction influences how genes are
regulated as well as generating long term effects in a species if
differential selection forces are present. As with all genetically
organism, behavior is subject to evolutionary adaptation.
As you study animal behavior in this lab,
think in terms of both proximate causes, the immediate
events that led to the behavior, and ultimate causes, the
of the behavior (Morgan & Carter, 2002).
arguably one of the
most important of all animal behaviors.
We will investigate feeding behaviors of the larva (caterpillar)
Cabbage White Butterfly (Pieris rapae). While the larvae are infamous as a
pest of brassica crops (such as cabbage,
and canola), the cream-colored butterflies are important pollinators of
plants (www.fastplants.org). During this activity, our goal will be to
determine if the caterpillars have a preferred food and what factors
influencing their “choice”.
- Discuss/define "behavior" - (see Langton's
- Observe caterpillars and butterflies.
- Summarize observations - what is known?...what is unknown?
- Devise experiments to test the summaries.
- In behavioral arenas, set up a choice test between
three food options.
- Place 3 foods equidistance around the perimeter
of the arena.
- Place a single larva in the center of the arena.
- Observe, time and take notes on the activities and
of the larva
- Repeat as many trials as time allows
- Revise summary based on experimental results
in "behavioral arena" - food preference assay
- Clean and dry a
glass bowl provided in lab.
- Obtain one
piece of each food type supplied and place them equidistance around the
perimeter of the arena.
- Obtain a larva
and place in the center of the arena and note its sex.
- Observe, time
and take notes on the activities and movements of the larva. We will pool all the data to obtain a
frequency of larval visits to each food type.
- When the larva
has moved to a food and begun eating or stayed for three minutes, start
a new trial at step one, but change the placements of the foods and the
position of the larva (i.e., change the direction the head is facing
when placed in the arena).
- If time allows
alter the experiment to test a new question that arose from your
initial observations. What is the stimulus?...color? …odor?
- Conduct a
Chi-Squared test of significance on pooled, class data. Your lab
instructor will guide you through this at the end of lab.