Insect Parasitic Nematodes

Nematodes are sold commercially to control a variety of soil-inhabiting insects, but most people have no idea what a nematode or nematode-infected insect looks like. Waxworms are ideal test subjects to show nematode infection because they are relatively large, are very susceptible to nematodes, and are readily available from most stores that sell live bait for fishing.

Fill a plastic container (such as a deli cup or cottage cheese carton) about half full of potting soil. Place several waxworms in the container and let them burrow into the soil or lightly bury them. Mix purchased nematodes according to the package directions. Pour a small amount of the nematode solution over the soil. The soil should be moist, but not saturated. Put the lid on the container and hold it at room temperature for 2 or 3 days. Dump out the contents and find the waxworms. How many are alive and how many are dead? What do the dead ones look like? Hold the dead ones in the empty container (with the lid on tight to prevent drying out) for another 10-14 days. Place a waxworm in a drop of water and carefully tear open the skin to observe what's inside (a microscope or magnifying lens is helpful). You should see lots of tiny wriggling worms (the nematodes!) moving around in the body fluid and water.

- Susan Mahr, University of Wisconsin - Madison

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