Larvicidal activity of the essential oil from Amomum subulatum Roxb. (Zingiberaceae) against Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus (Diptera: Culicidae), and non-target impact on four mosquito natural enemies

Mosquitoes (Diptera: Culicidae) are the primary vectors of several serious diseases that affect both animals and humans. Most of these diseases, especially the ones that are caused by arboviruses such as Zika, dengue and Japanese encephalitis, cannot be effectively prevented or treated, thereby rendering the discovery of alternative measures for the control of mosquito-borne diseases an absolute necessity. The current study evaluates the acute toxicity of Amomum subulatum-derived essential oil against Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. We used gas chromatographye-mass spectros-copy to analyze the chemical composition of A. subulatum EO. Analysis revealed thirty-three components. Primary constituents were 1,8- cineole (39.8%) and alpha-terpineol (11.5%). The essential oil from A. subulatum demonstrated a significant toxic effect against An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus third instar larvae, with LC50 values of 41.25, 44.11 and 48.12 mu g/ml and LC90 values of 80.29, 85.6 and 89.30 mu g/ml, respectively. Concerning non-target effects in the aquatic environment, we evaluated the acute toxicity of A. subulatum oil on 4 mosquito biocontrol agents, Anisops bouvieri, Diplonychus indicus, Poecilia reticulata and Gambusia affinis. We observed that the toxicity of this oil was extremely low, with LC50 ranging between 3123 and 9104 mu g/ml. In conclusion, the A. subulatum essential oil is an interesting bioresource to develop environmental friendly mosquito larvicides. Indeed, it is effective against different Culicidae species with LC50 always lower than 50 mu g/ml, while LC50 calculated for nontarget organisms are about 100-fold higher. (C) 2017 Elsevier Ltd. All rights reserved.