233 Scientific Publications Relating to Insect Vectors from 1995 to 2004 Phytochemicals as Repellents against Mosquitoes in Thailand Usavadee Thavara, Apiwat Tawatsin and Jakkrawarn Chompoosri National Institute of Health, Department of Medical Sciences, Ministry of Public Health. Published in Proceedings International Conference on Biopesticide 3, April 21-26, 2002, Kuala Lumpur, Malaysia, 244-250. Abstract Repellents are commonly used for personal protection against mosquitoes worldwide. They are one of the most effective products used in prevention and control of mosquito-borne tropical diseases. Although there are a number of effective repellents containing chemical active ingredients, such as deet, KBR 3023 and IR3535 there is in concern with regard to chemical toxicity. To overcome this concern phytochemicals extracted from various plants have been formulated as mosquito repellents to be 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 protection offered by these products was 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 is the minimum in requirement. These qualified repellent products were formulated as lotion, spray, cream and balm, where citronella oil, eucalyptus oil and tea tree oil were the main active ingredients. On the other hand, the NIH also formulated a 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. Keywords Repellents, mosquitoes, phytochemicals, biopesticides