CORRELATION OF VARIATION IN THE PERCENTAGE OF COMPOUNDS RESPONSIBLE FOR MOSQUITO REPELLENT ACTIVITY IN CITRONELLA OIL OVER TIME WITH MOSQUITO REPELLENT EFFICACY OF COMMERCIAL CITRONELLA OIL SAMPLES AND SPRAYS

The control of mosquitoes, which transmit deadly diseases, has become a significant public health concern globally. Protection against mosquito bites is an important part of preventing mosquito-borne diseases. Citronella oil extracted from two types of citronella grass Cymbopogon winterianus Jowitt (Java type) and Cymbopogon nardus (L.) Rendle (Ceylon type) possess compounds responsible for mosquito repellent activity. In the Sri Lankan market, there are some mosquito repellent products manufactured using citronella oil. In the present study, commercial citronella oil samples were subjected to GC-MS analyses weekly for sixteen weeks to investigate the variation in the percentage of compounds responsible for mosquito repellent activity with time and to correlate this variation to mosquito repellent efficacy of commercial citronella oil samples and sprays. In the tested samples, the percentages of compounds responsible for mosquito repellent activity as well as their mosquito repellent activity have shown a decline with time. The time duration that the maximum mosquito repellent activity would persist in the tested samples may be considerably lower than the shelf life stipulated. Therefore, one must consider this when relying on this mosquito repelling agents to prevent being bitten by mosquitoes.