Affiliation: * National Institute of Health, Department of Medical Sciences, Ministry of Public Health, 88/7 Tiwanon Road, Nonthaburi 11000, Thailand
Source: Presented in the 3rd International Conference on Biopesticides, Kuala Lumpur, Malaysia, 22-26 April 2002
Repellents are now commonly used for personal protection against mosquitoes worldwide. They are one of the most effective devices used in the control of mosquito-borne tropical diseases. Although there are many effective repellents containing chemical active ingredients, such as deet, IR3535 and KBR-3023 currently available in the market, there is more increasing in concern with chemical toxicity. Phytochemicals extracted from various plants, thus, have been formulated as mosquito repellents tobe sold in Thailand in recent years. Since the year 2000, 44 formulations of mosquito repellents containing plant extracts as active ingredients were evaluated for repellency against Ae. aegypti under laboratory conditions at the National Institute of Health (NIH), Thailand. These extracts included citronella oil, eucalyptus oil, tea tree oil, turmeric oil, bergamot oil, lavender extract, tobacco-leaves extract, clove extract and neem-leaves extract. The repellency results obtained from these products were up to 6.3 hours. However, only 12 products were qualified for registration to be sold in the market since minimum protection time of 2 hours were required. These qualified repellentproducts were formulated as lotion, spray, cream and balm, whereas citronella oil, eucalyptus oil and tea tree oil were the main active ingredients. On the other hand, the NIH also formulated mosquito repellent containing turmeric oil and eucalyptus oil as active ingredients. It was found that this repellent provided protection time for 7 hours against Ae. aegypti, and at least 8 hours against Culex quinquefasciatus and Anopheles dirus under laboratory conditions. This study demonstrated and encouraged the development of alternative active ingredients derived from plants to be formulated as effective mosquito repellents.