The essential oil from Zanthoxylum monophyllum a potential mosquito larvicide with low toxicity to the non-target fish Gambusia affinis

Abstract

The mosquito larvicidal activity of Zanthoxylum monophyllum leaf essential oil (EO) and its major chemical constituents was tested against the three mosquito vectors Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus. In the EO of Z. monophyllum, it contains 36 compounds with the two major compounds being Germacrene D-4-ol (19.40 %) and α-Cadinol (12.30). The larvicidal activity of the essential oil against An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus was determined and LC50 values were estimated at 41.50, 45.35 and 49.01 µg/mL, respectively. The two major compounds Germacrene D-4-ol and α-Cadinol were tested for acute toxicity against larvae of the three mosquito vectors. Germacrene D-4-ol showed a significantly higher efficacy compared to α-Cadinol. While LC50 for Germacrene D-4-ol ranged from 6.12 to 7.26 µg/mL, LC50 values for α-Cadinol were estimated in the range from 10.27 to 12.28 µg/mL. The EO, Germacrene D-4-ol and α-Cadinol were found safer to the non-target organism Gambusia affinis (LC50 = 4234.07, 414.05 and 635.12 µg/mL, respectively), which was manifested in the high suitability of the index/predator safety factor value, ranging from 86.36 for the least sensitive larvae of Cx. tritaeniorhynchus to 102.02 for the most sensitive larvae of An. subpictus.