Toxicity of ar-curcumene and epi-β-bisabolol from Hedychium larsenii (Zingiberaceae) essential oil on malaria, chikungunya and St. Louis encephalitis mosquito vectors

- Hedychium larsenii essential oil (EO) was studied as larvicide and ovideterrent on three mosquito vectors.
- The chemical composition of the EO was investigated by GC and GC-MS.
- Ar-curcumene and epi-β-bisabolol were the major EO constituents.
- These compounds showed high larvicidal and ovideterrent potential on all mosquitoes.
- Little EO toxicity rates were calculated for non-target mosquito predator Poecilia reticulate.

Mosquitoes act as vectors of key pathogens and parasites. Plant essential oils have been recognized as important sources of biopesticides, which do not induce resistance and have limited toxic effects on human health and non-target organisms. In this research, we evaluated the larvicidal and oviposition deterrence activity of Hedychium larsenii essential oil (EO) and its major compounds ar-curcumene and epi-β-bisabolol. Both molecules showed high toxicity against early third instars of Anopheles stephensi (LC50=10.45 and 14.68 µg/ml), Aedes aegypti (LC50=11.24 and 15.83 µg/ml) and Culex quinquefasciatus (LC50=12.24 and 17.27 µg/ml). In addition, low doses of ar-curcumene and epi-β-bisabolol were effective as oviposition deterrents against the three tested mosquito species. Notably, the acute toxicity of H. larsenii oil and its major compounds against the mosquito biocontrol agent Poecilia reticulata was low, with LC50 higher than 1500 ppm. Overall, the results from this study revealed that ar-curcumene and epi-β-bisabolol from the H. larsenii oil can be considered for the development of novel and effective mosquito larvicides.

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