Essential Oils from Vietnamese Asteraceae for Environmentally Friendly Control of Aedes Mosquitoes

Abstract

Mosquitoes, in addition to being a biting nuisance, are vectors of several pathogenic viruses and parasites. As a continuation of our work identifying abundant and/or invasive plant species in Vietnam for use as ecologically friendly pesticidal agents, we obtained the essential oils of Blumea lacera, Blumea sinuata, Emilia sonchifolia, Parthenium hysterophorus, and Sphaeranthus africanus; analyzed the essential oils using gas chromatographic techniques; and screened the essential oils for mosquito larvicidal activity against Aedes aegypti and Aedes albopictus. The most active larvicidal essential oils were B. sinuata, which was rich in thymohydroquinone dimethyl ether (29.4%), (E)-β-caryophyllene (19.7%), α-pinene (8.8%), germacrene D (7.8%), and α-humulene (4.3%), (24-h LC50 23.4 and 29.1 μg/mL) on Ae. aegypti and Ae. albopictus, respectively, and Emilia sonchifolia, dominated by 1-undecene (41.9%) and germacrene D (11.0%), (24-h LC50 30.1 and 29.6 μg/mL) on the two mosquito species. The essential oils of P. hysterophorus and S. africanus were also active against mosquito larvae. Notably, B. sinuata, P. hysterophorus, and S. africanus essential oils were not toxic to the non-target water bug, Diplonychus rusticus. However, E. sonchifolia essential oil showed insecticidal activity (24-h LC50 48.1 μg/mL) on D. rusticus. Based on these results, B. sinuata, P. hysterophorus, and S. africanus essential oils appear promising for further investigations.

Larvicidal, Ovicidal, and Repellent Activities of Leucas stachydiformis (Hochst. ex Benth.) Briq Essential Oil against Anopheles arabiensis

“…Larvicidal properties of the essential oil of L. stachydiformis may be linked to its major constituents such as caryophyllene oxide, germacrene D, linalool, and α-humulene which have been reported to have strong larvicidal properties [27,[29][30][31]. However, the efect of these major constituents might have been strengthened by the cooccurrence of minor compounds that act in an additive and/or synergistic manner [32]. Among the minor constituents of the oil, α-pinene, verbenone, bicyclogermacrene, δ-cadinene, and α-terpineol were reported to have larvicidal activity [1,29,32,33].…”

“…However, the efect of these major constituents might have been strengthened by the cooccurrence of minor compounds that act in an additive and/or synergistic manner [32]. Among the minor constituents of the oil, α-pinene, verbenone, bicyclogermacrene, δ-cadinene, and α-terpineol were reported to have larvicidal activity [1,29,32,33]. Diferent phytochemicals are known to cause neurotoxicity or direct contact toxicity to the midgut epithelium of mosquito larvae [34].…”

Larvicidal, Ovicidal and Repellent Activities of Leucas stachydiformis (Hochst. ex Benth.) Briq Essential Oil against Anopheles arabiensis

“…Larvicidal properties of the essential oil of L. stachydiformis may be linked to its major constituents such as caryophyllene oxide, germacrene D, linalool, α-humulene which have been reported to have strong larvicidal properties [20][21][22][23]. But, the effect of these major constituents may have been strengthened by the co-occurrence of minor compounds that act in an additive and/or synergistic manner [24].…”

“…But, the effect of these major constituents may have been strengthened by the co-occurrence of minor compounds that act in an additive and/or synergistic manner [24]. Among the minor constituents of the oil, α-pinene, verbenone, bicyclogermacrene, δ-cadinene, and α-terpineol were reported to have larvicidal activity [1,22,25,26] Different phytochemicals are known to cause neurotoxicity or direct contact toxicity to the midgut epithelium of mosquito larvae [27]. In the present study, the identi ed essential oil constituents such as caryophyllene oxide, α-pinene, linalool are known to have anti-acetylcholinesterase activity [28], whereas α-terpineol was reported to have in uence on the production of cyclic adenosine monophosphate (cAMP) and calcium at the cellular level and these effects consequentially lead to larval death [29].…”