Essential oil of Piper purusanum C.DC (Piperaceae) and its main sesquiterpenes: biodefensives against malaria and dengue vectors, without lethal effect on non-target aquatic fauna

The mosquito vectors of the genera Aedes and Anopheles present resistance to several commercial insecticides, which are also toxic to non-predator targets. On the other hand, essential oils are a promising source of insecticides. Thus, in this work, the essential oil from the leaves of Piper purusanum was characterized by gas chromatography–based approaches and evaluated as biodefensive against malaria and dengue vectors. The main compounds of P. purusanum essential oil were β -caryophyllene (57.05%), α -humulene (14.50%), and germacrene D (8.20%). The essential oil inhibited egg hatching (7.6 ± 1.5 to 95.6 ± 4.5%), caused larval death ( LC 50 from 49.84 to 51.60 ppm), and inhibited the action of acetylcholinesterase ( IC 50 of 2.29 µg/mL), which can be related to the mechanisms of action. On the other hand, the biological activities of β -caryophyllene, α -humulene, and germacrene D were higher than that of essential oil. In addition, these sesquiterpenes and essential oil did not show a lethal effect on Toxorhynchites splendens , Anisops bouvieri , Gambusia affinis , and Diplonychus indicus ( LC 50 from 2098.80 to 7707.13 ppm), although D. indicus is more sensitive ( SI / PSF from 48.56 to 252.02 ppm) to essential oil, representing a natural alternative against these relevant vectors.