Essential oils of indigenous in Greece six Juniperus taxa Chemical composition and larvicidal activity against the West Nile virus vector Culex pipiens

The chemical composition of 14 essential oils (EOs), obtained from various parts (leaves, fruits, wood) of the six indigenous in Greece Juniperus family taxa, was determined by GC and GC/MS analysis. The insecticidal properties of these EOs were evaluated against Culex pipiens L. larvae of 3rd and early 4th instars, in order to delineate the relationship between the phytochemical content of the EOs and their larvicidal activities. The analytical data indicated that the EOs mainly consisted of monoterpenes, mostly cyclic and only occasionally aliphatic, and to a lesser percent, of diterpenes. The larvicidal bioassays against C. pipiens larvae revealed that the most active EO was derived from the wood of Juniperus drupacea and contains mainly non-oxygenated monoterpenes and a significant amount of diterpenes, displaying the highest chemodiversity. Its initial LC50 value was 26.47 mg L-1. On the contrary, the EO isolated from J. phoenicea berries, which consisted of monoterpenes (non-oxygenated, cyclic), was the less active displaying an LC50 value of 96.69 mg L-1. In respect to the contained phytochemicals, myrcene was assayed as the most toxic, displaying an LC50 value of 33.83 mg L-1, while the four isomers of pinene abundant in all EOs were less active exhibiting LC50 values ranging from 70.40 to 94.88 mg L-1. Results herein reveal that the EOs isolated from the studied Juniperus family taxa represent an inexpensive source of natural mosquito control mixtures.