Laboratory bioassays were conducted to determine the activity of 15 natural products isolated from essential oil components extracted from the heartwood of Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach., against Ixodes scapularis Say nymphs, Xenopsylla cheopis (Rothchild), and Aedes aegypti (L.) adults. Four of the compounds from the essential oil have been identified as monoterpenes, five as eremophilane sesquiterpenes, five as eremophilane sesquiterpene derivatives from valencene and nootkatone, and one as a sesquiterpene outside the eremophilane parent group. Carvacrol was the only monoterpene that demonstrated biocidal activity against ticks, fleas, and mosquitoes with LC50 values after 24 h of 0.0068, 0.0059, and 0.0051% (wt:vol), respectively. Nootkatone from Alaska yellow cedar was the most effective of the eremophilane sesquiterpenes against ticks (LC50 = 0.0029%), whereas the nootkatone grapefruit extract exhibited the greatest biocidal activity against fleas (LC50 = 0.0029%). Mosquitoes were most susceptible to one of the derivatives of valencene, valencene-13-aldehyde (LC50 = 0.0024%), after 24 h. Bioassays to determine residual activity of the most effective products were conducted at 1, 2, 4, and 6 wk after initial treatment. Residual LC50 values for nootkatone did not differ significantly at 4 wk posttreatment from the observations made at the initial 24-h treatment. The ability of these natural products to kill arthropods at relatively low concentrations represents an alternative to the use of synthetic pesticides for control of disease vectors.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.