สถาบันวิจัยวิทยาศาสตร์สาธารณสุข

NATIONAL INSTITUTE OF HEALTH OF THAILAND

Field testing of repellents derived from plant essential oils against mosquitoes (Diptera: Culicidae), black flies (Diptera: Simuliidae) and land leeches (Arhynchobdellida: Haemadipsidae) in Thailand

Authors : Apiwat Tawatsin*, Usavadee Thavara*, U-ruyakorn Chansang*, Pranee Chavalittumrong**, Thidarat Boonruad**, Prapai Wongsinkongman**, Jaree Bansidhi**, Mir S. Mulla***

 

Affiliations:        * National Institute of Health, Department of Medical Sciences, Ministry of Public Health, 88/7 Tiwanon Road, Nonthaburi 11000, Thailand
** Medicinal Plant Research Institute, Department of Medical Sciences,
Ministry of Public Health, 88/7 Tiwanon Rd., Nonthaburi 11000, Thailand
*** Department of Entomology, University of California, Riverside, CA 92521, U.S.A
 
Source:             Presented in the 4th International Congress of Vector Ecology (SOVE),Reno, Nevada, U.S.A., 2 – 7 October 2005
 
Language:         English
 
Abstract:
 
Essential oils from parts of 3 species of plants (finger root rhizomes, guava leaves and turmeric rhizomes), steam distillated and formulated as insect repellents were tested in the field on human volunteers against mosquitoes, black flies and land leeches in Thailand. For comparison, testing of a commercial plant-based repellent (Repel Care®) and deet was also included. The tests against wild mosquitoes were conducted in Bang Bua Thong District, Nonthaburi Province and at the Thap Lan National Park Headquarter, Nadee District, Prachinburi Province while those against anthropophilic black flies were conducted at the Forestry Fire Control Station in the Doi Inthanon National Park, Chomthong District, Chiang Mai Province and those against land leeches were carried out in the Khao Yai National Park, Pak Chong District, Nakhon Ratchasima Province. The 3 experimental plant-based essential oil formulations provided complete protection from mosquito landing and biting for up to 9 hours (duration of the experiment), equaling the protection provided by Repel Care® and deet. There was no difference in the duration of complete protection provided by the 5 repellent products. Similar results were obtained with the 5 products against black flies, providing 100% protection for 9 hours, but extent of protection declining to 82-96%, 10 hours and 11 hours post-treatment. There was no significant difference in affording protection from black fly attacks among the different products at any of the post-treatment intervals. A complete protection (100%) against land leeches for at least 8hours was obtained from the 5 repellent products. This is the first report of repellency of plant-based repellents against black flies and land leeches. The identification and availability of cheap sources of plant-based oils such as those from finger root rhizomes, guava leaves and turmeric rhizomes providing long-lasting repellency are promising leads into commercial production of safe and effective repellents.