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The Study of Natural Insect Populations

  • TITLE: THE STUDY OF NATURAL INSECT POPULATIONS
  • LEVEL: GRADES 6 - 8
  • DURATION: ONE TO SIX WEEKS
  • DEVELOPED BY: STEPHEN ZAWISTOWSKI, Ph.D., ASPCA SCIENTIFIC ADVISOR

SCIENCE OBJECTIVE #4

Create models of non-intrusive, productive animal research through natural (non-manipulative) observation.

UNIT OVERVIEW:

The activities of this unit will provide students with hands-on manipulative experience, an introduction to the skills of behavioral observation and data collection and an appreciation of the complex nature of insect ecology and behavior.

Students will make artificial feeding stations for insects and place these in a variety of locations. They will observe and record the numbers and types of insects which come to feed, and the interactions that occur between individuals at the feeding station. They will attempt to identify the key variables that affect the numbers and types of insects that come to feed, including constitution of the food provided, placement of the food and time of day.

BACKGROUND:

Feeding stations provide excellent locations to observe animal behavior. Large mammals are often observed while feeding or at a watering hole. Sharks may be baited to an area where they can be observed by divers in protective cages. These studies and other similar ones have reveled important information on elements of individual behavior as well as group dynamics between and within species.

Many insects rely on fruits as a food source because they are rich in sugars and other important nutrients. Fruits that begin to ferment due to the action of yeasts also offer a good protein source in the form of the yeasts. Fruits also provide much needed moisture and possible substrata for egg laying. The study of insects can help students to develop an overall awareness of the complex systems of behavior that govern the feeding, reproduction and other activities of individuals. An appreciation of these concepts can help a student develop an overall philosophy that understands and respects all elements of nature.

These are two basic types of life stages among the larger insects. Flies, butterflies, beetles and bees are some of the insects that have a complete metamorphosis. They have four life stages: egg, larva. pupa and adult. Many aquatic insects, as well as cockroaches, exhibit three stages: egg, nymph and adult. Nymphs are wingless, smaller forms of the adult. A larva or pupa usually is completely different from the adult form.

PERFORMANCE OBJECTIVE:

Students will learn how to make a feeding station for insects and then observe the numbers and types of insects that come to feed.

MOTIVATION: Have students attempt to identify the type of insects that frequent the site chosen for the study. They should also try to identify the possible food source found in the area.

AIMS: Students will develop hands-on motor skills through preparation of the food. Several variations in food preparation will allow them to refine their understanding of the experimental method and the control of independent variables. They will also practice important observational skills.

ACTIVITIES:

  • Begin by identifying a potential study site. It should be accessible and safe. The best time for observation will be morning and late afternoon. Try to identify some of the insects present at the site. Any one of a number of good insect identification books can be used to assist the student.
  • Assemble the materials needed to make the food mixture: dry yeast, several pieces of fruit, plastic bags and a blender.
  • The food bait is made by grinding the fruit in the blender with the yeast and enough clean water to result in a smooth, pudding-like product. Pour this mixture into a bowl, cover it and allow it to stand overnight. The mixture is then poured into a plastic bag.
  • The food bag is then hung in a tree, close to the trunk. A pencil, or some other similar object can then be used to drip along the trunk of the tree.
  • The following morning, the student should choose a convenient location to observe the insects that come to feed at the food drip. It can be useful for the student to use a telescope or binoculars to assist with the observation.
  • During the observation period, notes should be taken on the number of insects seen at the feeding site and type of insect. Students can also keep records on the length of time that individuals stay to feed and the types of interactions that occur between different individuals.
  • Several different food mixtures can be prepared, using different fruits or vegetables and with, or without, the yeast. The student can then determine if there is a preference for one type of fruit or whether the presence of the yeast is critical.
  • Students can make an alternative mixture of fruit, herbs and/or spices such as garlic, oregano and basil, using procedures described previously and noting insect reaction.

POSSIBLE SCIENCE FAIR PROJECT:

Students can report on the insects that have visited their feeding station. Library research can help provide background information on particular insects. Charts on the types, numbers of insects, lengths of time the individual insects stay to feed, food preferences and dislikes and types of interactions between different individuals should be included. Photos of insects at the feeding station, as well as student drawings, would enhance this project.

BIBLIOGRAPHY:

  • Fry, R. and Lonsdale, D. (Editor) Habitat Conservation for Insects - A Neglected Green Issue, 1991
  • Mound, Laurence, Insect (Eyewitness Books), Alfred A. Knopf, USA, 1990.
  • Nardi, James B. Close Encounters with Insects and Spiders, Iowa State University Press, 1988.
  • Neary, John, Insects and Spiders, (Wild, Wild World of Animals Series), Time-Life Films, 1977.
  • O'Toole, Christopher, Insects and Spiders, (Encyclopedia of the Animal World), Facts on File, 1990.
  • Wechsler, Bizarre Bugs, National Academy of Natural Sciences, phone # 1-888-229-ANSP
  • Website: http://www.insect-world.com

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