attached
Volatile oils also known as essential oils are found in aromatic plants and contain volatile
compounds that contribute to particular fragrances and flavours. Main uses of these volatile
oils range from aroma therapy, food additives, cosmetics, natural medicines to insect
repellents. Although there are common plants that produce volatile oils capable as mosquito
repellents, certain plants are not known for this ability or under-utilised. Therefore, this
research aimed at identifying lesser known volatile oil producing species and to formulate the
plant products into safe and low cost insect repellents. An expert survey was first conducted
by interviewing 7 subject experts and 13 local ayurvedic practitioners to identify the existing
and potential volatile oil producing plant species which can be used as mosquito repellents.
This survey identified 60 species and out of those 16 species (Ocimum tenuiflorum,
Azadirachta indica, Acorus calamus, Atalantia ceylanica, Ocimum sanctum, Plectranthus
amboinicus, Plectranthus zatarhendi, Vetiveria zizanioides, Acronychia pendunculata,
Osmium gratissium, Aegle marmelos, Limonia acidissima, Murraya koenigii, Ricinus
communis, Cinnamomum verum and Tagetes erecta) was selected after a weighted ranking
system for further study. Hydro-distillation for 5 hours was used with 100 g of leaves for oil
extraction for each species with three replicates. Particle size was kept at 1.5 cm for this
purpose with 1:12 water ratio. Oil constituents were identified using GC-MS analysis.
According to the results C. verum yielded the highest mean oil content (0.0113±0.0024 ml/g)
followed by A. marmelos (0.0095±0.0018 ml/g). A. ceylanica bears the highest number of
constituents followed by M. koenigii and L. acidissima. However, the highest number of
constituents which act as mosquito repellents showed by L. acidissima and C. verum as the
present study. Those constituents are α-Pinene, 3-Carene, Terpinolene, Caryophyllene oxide
in C. verum and α-Pinene, Limonene, Terpinolene and Caryophyllene oxide in L. acidissima.
