title: Ability of two natural products, nootkatone and carvacrol, to suppress Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) in a Lyme disease endemic area of New Jersey.
abstract: We evaluated the ability of the natural, plant-derived acaricides nootkatone and carvacrol to suppress Ixodes scapularis Say and Amblyomma americanum (L.) (Acari: Ixodidae). Aqueous formulations of 1 and 5% nootkatone applied by backpack sprayer to the forest litter layer completely suppressed I. scapularis nymphs through 2 d. Thereafter, the level of reduction gradually declined to < or =50% at 28 d postapplication. Against A. americanum nymphs, 1% nootkatone was less effective, but at a 5% concentration, the level of control was similar or greater to that observed with I. scapularis through 21 d postapplication. Initial applications of 0.05% carvacrol were ineffective, but a 5% carvacrol formulation completely suppressed nymphs of both species through 2 d and resulted in significant reduction in I. scapularis and A. americanum nymphs through 28 and 14 d postapplication, respectively. Backpack sprayer applications of 5% nootkatone to the shrub and litter layers resulted in 100% control of I. scapularis adults through 6 d, but the level of reduction declined to 71.5% at 28 d postapplication. By contrast, high-pressure applications of 2% nootkatone to the litter layer resulted in 96.2-100% suppression of both I. scapularis and A. americanum nymphs through 42 d, whereas much lower control was obtained from the same formulation applied by backpack sprayer. Backpack sprayer application of a 3.1% nootkatone nanoemulsion resulted in 97.5-98.9 and 99.3-100% reduction in I. scapularis and A. americanum nymphs, respectively, at 1 d postapplication. Between 7 d and 35 d postapplication, the level of control varied between 57.1% and 92.5% for I. scapularis and between 78.5 and 97.1% for A. americanum nymphs. The ability of natural products to quickly suppress and maintain significant control of populations of these medically important ticks at relatively low concentrations may represent a future alternative to the use of conventional synthetic acaricides.
authors.affiliation: Division of Vector-Borne Infectious Diseases, National Center for Zoonotic, Vector-Borne and Enteric Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA. mcd4@cdc.gov
authors.forename: Marc C
authors.initials: MC
authors.lastname: Dolan
authors.forename: Robert A
authors.initials: RA
authors.lastname: Jordan
authors.forename: Terry L
authors.initials: TL
authors.lastname: Schulze
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Schulze
authors.forename: Mark Cornell
authors.initials: MC
authors.lastname: Manning
authors.forename: Daniel
authors.initials: D
authors.lastname: Ruffolo
authors.forename: Jason P
authors.initials: JP
authors.lastname: Schmidt
authors.forename: Joseph
authors.initials: J
authors.lastname: Piesman
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Karchesy
mesh_terms: D056810:Acaricides; D000818:Animals; D029780:Chamaecyparis; D000081007:Cymenes; D018884:Ixodes; D008193:Lyme Disease / Q000517:prevention & control; D039821:Monoterpenes; D009515:New Jersey; D010936:Plant Extracts; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; D013983:Tick Control
chemical_list: D056810:Acaricides; D000081007:Cymenes; D039821:Monoterpenes; D010936:Plant Extracts; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; C073316:carvacrol; C050302:nootkatone