Resin from an East African tree related to myrrh contains chemicals that could be used as tick repellants by humans, pets and livestock. Dr. John Carroll and Dr. Dave Warthen, scientists from the USDA's Research Service in Beltsville, Maryland, and Tanzanian Fulbright scholar Dr. A. Maradufu worked closely together to find that oil from Commiphora erythraea kills larvae and repels adults of the Lone Star and American Dog ticks and also repels adult Deer ticks. In Africa, gum from the bark of C. erythraea is rubbed on cattle to repel ticks and insects and to soothe cuts, bruises and scabies. It has also been used traditionally in Somalia as a folk medicine and as a perfume because of its pleasant odor.

In laboratories at USDA, the collected gum from C. erythraea bark was blended and filtered to extract the oil used in experiments. Less than 1% of the Lone Star tick larvae and adults, and less than 16% of the Dog and Deer tick adults, crawled onto a section of a cloth strip that had been soaked in a dilute solution of the oil extract. By comparison, 73% to 83% of the ticks crawled the same distance on another piece of cloth containing a chemical control. Larvae of the Lone Star and American Dog ticks died within 24 hours between filter papers soaked with the oil.

During earlier research at the Tropical Pesticides Research Institute in Arusha, Tanzania, Dr. Maradufu isolated three chemicals called furanosesquitenoids that are toxic to larvae of the African Brown Ear tick. The researchers are still not sure whether these are the same chemicals that repel the American tick species. Once the active ingredients from the plant are identified and purified, they may have potential as natural repellants or toxins against ticks. The gum could also be much more widely used on local livestock as a tick repellant. Collaborative research in this area continues.

For more information contact:

Dr. Asafu Maradufu
Tropical Pesticides Research Institute
PO Box 3024
Arusha, Tanzania

Dr. John Carroll
Livestock Insects Laboratory
Agricultural Research Center
Beltsville, MD 20705