Activities: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10

Activity Eight
Beetle Rearing

Objectives
Students will:

Methods
In small groups, students will collect root crowns, prepare pots, plant the root crowns, and care for the potted plants. When the plants reach the right size, beetles will be released onto mesh cages surrounding the plants and pots and their growth and development monitored. At the appearance of the new generation of adults, the beetles will be released at several heavily infested sites and their progress and effects on the loosestrife plants monitored through the summer into the fall. Following is a typical timeline for rearing and releasing Galerucella beetles. 1) Pot Root Crowns - April 5 2) Place beetles into cages - May 10 3) Release beetles - June 15-30 (Times will depend on local conditions)

Background
In order to have an adequate supply of beetles to release for loosestrife control, it is necessary that the beetles be cultured in large numbers. This cannot be easily done in the indoor facilities of most schools, but many schools have courtyards or other outdoor areas protected from vandal or animal damage in which large numbers of loosestrife plants can be maintained. This not only helps with the supply of beetles needed, but it gives students knowledge and skills useful in growing and propagating other flowering plants. It also provides an opportunity for students to design and carry out other experiments or observations on the plants not used to grow beetles.

Materials
Outdoor Beetle Rearing Kit (Many of these materials may be obtained by soliciting local businesses for donations of materials)

Procedure:
Locate a wetland area near school with a large population of overwintering purple loosestrife plants and collect approximately 20 root crowns with 5-6 stems. If this is done in the fall after the plants have become dormant, the root crowns may be stored under a tarp or other cover till spring. Alternatively the root crowns may be dug in March before they are actively sprouting and potted immediately. A plastic wading pool about 6 feet in diameter is used to supply water to the potted plants during growth.

Fifteen four gallon pots are half filled with a non-soil potting mix, a tablespoon of slow release fertilizer such as Osmocote is sprinkled on the soil surface and the root crown is placed into the soil. The remainder of the pot is then filled with further potting soil. The soil should not be packed down, but may be tapped to help it settle. The pots are then placed into the wading pool in water about 2-3 inches deep and watered once from the top. From then on, all watering should be done by adding water to the wading pool.

A tomato cage is placed into each pot and pressed down firmly to seat it. The sharp edges and joints of the tomato cages should be taped to prevent damage to the mesh cage sleeves when they are put over the cages and pots. Since the plants will be outside, the mesh sleeves should be placed over the cages immediately and secured top and bottom with twine, tape or a heavy rubber band to prevent entry of aphids, predators or other pests that might interfere with the plant or beetle growth.

Place the wading pool in a protected area away from possible vandals, animals or strong winds. Space 15 of the pots evenly in the pool so that each receives plenty of light and air can circulate freely. Fill the pool up to 3" with water and check and refill as needed daily throughout the growing period. An overflow hole should be cut into the side of the pool about 5" from the ground to allow heavy rain to escape. When the stems reach about 14 inches, pinch off about ½ inch of the tip of each stem to encourage lateral stem growth and provide plenty of food for the beetles.

Securely tie the top and the bottom of the mesh cage to prevent loss of the beetles. The Galerucella adults should begin feeding immediately and after 1-2 weeks begin laying eggs on the plants. The eggs are layed in small groups on either stems or leaves and are round, pin head sized eggs with a black stringy deposit across the top of the egg mass. Eggs hatch within 2 weeks. The larvae are yellow to orange with black stripes across the body. They have several growth stages called instars and feed on the fresh leaf tips and flower buds. They will be hard to see at first, but they eat the upper layer of the leaves producing "window-paning" starting at the top of the plant and moving downward.

The larvae take about 3 weeks to become full grown and then burrow into the soil to become pupae. Pupae do not feed or move around and after about two weeks, the adult beetles begin to appear and collect near the top of the plant. When these are visible and the plants are nearly defoliated, it is time to release the beetles or collect the adults for distribution to other schools.

Choose a release area with a thick growth of loosestrife, but in open sunlight. The release site should be out of easy sight by possible vandals. The entire plant and pot should be moved to the release site and the mesh and cage removed next to a fresh supply of wild plants. Shake any beetles still in the bag out and remove the tomato cage. The spot of release should be recorded carefully on a map and marked with 4 white PVC pipes stuck in the ground. It is important that the site can be located by more than one method (pipes, measurements, etc.) because vandals, ice and plant growth may obliterate or move your markers over several years.

Extensions
Students may record abiotic conditions, such as temperature, cloudiness, length of day, etc. as well as plant measurements and appearance over the time of the project. Problems may arise with either the plant growth or the beetle population growth that may lead to discussion and attempted solutions. Students may use stereo microscope, magnifiers and measuring devices to record the stages in the Galerucella life cycle. Some larvae and adults may be used for observations and experiments relating to behavior and food selection. Information may be shared about the project with other cooperating schools by Internet, mail or telephone. The project may be continued during the summer by volunteer groups of students or other interested groups may be enlisted and trained to do so (such as summer school classes, scouts, 4-H or other groups. Class activities may be recorded by videotape, school newspaper, and local media to keep the community informed of the progress of the project.

Evaluation
Evaluation can be based on informal observations of students and groups during the project, lab notebook records, observation of group problem solving meetings, student presentations to the class or community organizations.

Activities: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10