A comparative study of the effects of various repellants on freshwater leeches.

Abstract

While leeches provide many valuable ecosystem services, they are also a pest species that may spread pathogens to humans and animals. We tested four different home repellents (DEET, lemon-eucalyptus oil, tobacco , and vinegar) to determine which were successful at repelling a species of freshwater leech, E. obscura. We applied each repellent to a piece of beef liver, which was suspended in a tank of leeches for 30 minutes, during which the number of leeches attaching to the liver were recorded in ten-minute intervals. We also recorded the pH of each treatment to compare the effects of acidity on leeches. We found that the percent of leeches attached for DEET, tobacco, and lemon-eucalyptus oil were significantly different than both the control and vinegar ; there was no difference between the vinegar and the control (F = 43.671, df = 4, p < 0.000). We also found the lemon-eucalyptus oil was quantitatively the most successful over time with 0 total attachments. We did not find a correlation between acidity and number of attachments. This knowledge may be useful in the protection against potential pathogens for people who spend time in freshwater ecosystems.