This lab exercise allows for two key principles to be examined, insect development through the incubation of Alfalfa Leafcutting bees and also pollination as the mature Bees pollinate Wisconsin fast plants.

The appeal of this lab is that the bees hatch out in a total of 28 days with males begining to hatch on day 18 and preceding the females for the first four days and the fast plants will coincide with the hatching of the bees if started 3-5 days earlier.

This exercise is presented with the procedure first, followed by discussion of the principles and process involved.

Exercise One - Alfalfa Leafcutting Bees, Megachile rotundata

This lab is performed using Alfalfa Leaf Cutter Bee cocoons starting at the prepupal stage, petri dishes, empty gel capsules, a razor blade, an incubator maintained at 86 degrees F, the handout "A calendar of Incubation of Alfalfa Leafcutting Bees", and a receptacle to maintain the mature bees..

The Alfalfa Leafcutting bee cocoons can be obtained from Ron Bitner at www.pollination.com, a list of potential suppliers for the other necessary items is also available on the website.

Objective

Follow the development of Alfalfa Leafcutting bees from prepupal stage to adult.

Procedure

1. Using a razor blade carefully open the Alfalfa Leafcutting bee cocoons, gently extract the larva and place it n a clear gel capsule. Each lab group will need approximately five to six larvas to insure success.
2. The gel capsules containing the bee larva should be placed in labeled Petri dishes and kept in an incubator at 86 degrees F.
3. Observations should be made every two to four days as the bees develop. Students can follow and chart development using the handout "A calendar of Incubation of Alfalfa Leafcutting Bees" as a reference.
4. After eighteen to nineteen days the bees will begin to hatch. Adult bees should be removed from the incubator and placed in a container allowing plenty of light and fresh air. The bees are photoreceptive so light is crucial a glass aquarium with a wire mesh lid works nicely. Also, a mixture of sugar and water should be available for the bees to feed upon.

**Note ** The bees should be used in Exercise Two - Wisconsin Fast Plants as soon as possible

Discussion

By removing the protective leaf covering of the cocoon and placing Alfalfa Leafcutting Bee larva in the gel capsules the developmental process is easy to observe. Students should be able to not the transformation from larva to pupa to adult. Also, students will be able to see the bees develop body segments/ parts and should be able to distinguish males from females by eye color.

It is a good idea to have students make sketches of the bees as the develop a detailed description of each stage of development is on the handout "A calendar of Incubation of Alfalfa Leafcutting Bees".

Exercise Two - Wisconsin Fast Plants

This lab is performed using adult Alfalfa Leafcutting Bees Megachile rotundata from Exercise One - Alfalfa Leafcutting Bees, Megachile rotundata, Wisconsin Fast Plant Brassica rapa seeds, Styrofoam planting chambers, wicks, felt, a container for water, sticks for stabilization, plating soil , a light source, and a pollination chamber.

All supplies for growing the Wisconsin Fast Plants can be obtained from Carolina Biological Supply Company at their website

Objective

To observe plant growth from seed to flower, and then to see alfalfa leaf cutting bees actively pollinating the fast plants

Procedure

1. Plant Wisconsin Fast Plants on the tenth day of incubating the Alfalfa Leafcutting Bees. Follow the instructions for planting provided with the fast plant seeds.
2. The development of the Fast Plants should coincide with the hatching of the Alfalfa Leaf Cutting Bees.
3. The students with observations every 2 to 3 days should chart development of the fast plants.
4. Once the Wisconsin Fast Plants flower they should be placed in the pollination chamber and the adult alfalfa leafcutting bees should be added. The pollination process will occur fairly quickly so students should be prepared to make observation upon introduction of the bees to the pollination chamber.

Discussion

The key concept in this exercise is the way that the Alfalfa Leafcutting bees actually pollinate the Wisconsin Fast Plants.

Conclusions

The two parts in this lab exercise coincide together resulting in the hands on experience of 3 key concepts: 1- insect development, 2-plant development, and 3- pollination. Student response has been good and strongly links the three processes. If time allows plant development as well as genetics can also be added into the lab exercise by following the growth of the Wisconsin Fast Plants and then as a secondary exercise crossing the different varieties of fast plants.

References

A calendar of Incubation of Alfalfa Leafcutting Bees