Photo by V. Miller
Aug. 10, 2005
Caffeine as a Pesticide
Caffeine as a Pesticide: Reproductive Effects, Year Two
Sara Catherine Clark, 14, Pipe Creek, Texas
Discovery Kids "TV Star" Award, Discovery Channel Young Scientist Challenge, 2004
Project background: Last year, Sara's project showed that strong caffeine solutions killed garden pests. This year she wanted to see if a lower concentration of caffeine could inhibit reproduction of slugs without killing beneficial red and black worms.
Tactics and results: Sara prepared caffeine solutions ranging in concentration from 0.0001 percent to 1.0 percent. She placed soil soaked with the caffeine solutions in plastic containers with redworms and spotted garden slugs. For the smaller black worms, Sara used micro test tubes instead. She checked the worms and slugs every day, counting survivors. After 30 days, she counted the number of eggs, cocoons, and young worms and slugs in each container or test tube.
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| Photo by V. Miller |
Sara found that slugs could not reproduce in solutions stronger than 0.005 percent caffeine, but at this concentration, redworms and black worms reproduced more frequently than control animals.
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