Location: Mosquito and Fly ResearchTitle: Identification of insecticidal principals from cucumber seed oil against the yellow fever mosquito, Aedes aegypti
|Tak, Jun-hyung - University Of Florida|
|Tsikolia, Maia - University Of Florida|
|Bernier, Ulrich - Uli|
|Linthicum, Kenneth - Ken|
|Bloomquist, Jeffrey - University Of Florida|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/2/2018
Publication Date: 2/15/2018
Citation: Tak, J., Tsikolia, M., Bernier, U.R., Linthicum, K., Bloomquist, J.R. 2018. Identification of insecticidal principals from cucumber seed oil against the yellow fever mosquito, Aedes aegypti. Meeting Abstract. pg. 1.
Technical Abstract: The yellow fever mosquito, Aedes aegypti, is one of the most medically important mosquito species due to its ability to spread viruses of yellow fever, dengue fever and Zika in humans. In this study, the insecticidal activity of seventeen plant essential oils were evaluated to toxicity by topical application against two strains of Ae. aegypti mosquito, Orlando (insecticide-susceptible) and Puerto Rico (pyrethroid-resistant. Among the essential oils tested, cucumber seed oil produced complete mortality (100%) at 10 'g/mosquito, and sandalwood and thyme oils also showed notable 1h knock-down effect, as well as high mortality (>80%) at 24 h in the susceptible strain. In contrast, sandalwood and thyme oils displayed relatively high mortality against the resistant strain, with resistance ratios of 2.1 and 1.4, respectively. Cucumber seed oil showed significantly lower activity with a resistance ratio of 44.5. Bioactivity-guided fractionation via flash-column chromatography produced eleven fractions, and fractions 1, 4, 5, and 6 showed significant mortality at the LD95 (2.3 'g/mosquito) of whole cucumber seed oil, but only fraction 5 showed comparable activity to the crude oil when the factions were applied at the equivalent amount that they are present in the oil (by considering their % yields). Surprisingly, the active fractions, 4, 5, and 6 contained 0.40, 0.48, and 0.29% chlorpyrifos, respectively, an organophosphate insecticide, and in non-active fractions, no trace of chlorpyrifos was observed in gas-chromatography/mass spectrometry (GC-MS) analysis. A further GC-MS analysis identified benzyl acetate, cyclamal, and linoleic acid as the major constituents of fraction 5, but neither individual compounds nor an artificial mixture of those three compounds produced similar activity of the fraction itself. Chlorpyrifos alone or in a mixture with the remaining three compounds showed significantly increased mortality, indicating the insecticidal activity of cucumber seed oil is probably due to the presence of insecticide. This contamination could happen during the cultivation of cucumber in the field, either via deliberate treatment, or spray drift from nearby fields. For future studies of natural products, particularly botanical insecticide research, the contamination of products with synthetic pesticides or other xenobiotics during cultivation, harvest, or processing steps must be thoroughly monitored and avoided.