The effectiveness of a CO2-derived cedarwood oil as alternative control for hard ticks

Authors: Weiler, Lina; Behle, Robert; Eller, Fred; Muturi, Ephantus; Rooney, Alejandro - Alex

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/18/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The repellency and toxicity of a CO2-derived cedarwood oil (CWO) was evaluated against actively questing unfed nymphs of four species of hard ticks; Amblyomma americanum (L.), Dermacentor variabilis (Say), Ixodes scapularis (Say), and Rhipicephalus sanguineus (Latrielle). Using a vertical climb bioassay for repellency, nymphs of these species avoided a CWO treated filter paper in proportional responses to treatment concentrations. At 60 minutes of exposure, Ixodes scapularis nymphs were most sensitive with 50% repellency concentration (RC50) of 19.8 µg cm-2, compared with RC50 of 30.8, 83.8, and 89.6 µg cm-2 for R. sanguineus, D. variabilis and A. americanum, respectively. Bioassays determined the lethal concentration for 50% (LC50) and 90% (LC90) mortality of nymphs exposed to CWO in treated vials after 24- and 48-hours exposure. After 24 hours exposure, the LC50 values were 1.25, 3.45 and 1.42 µg cm-2 and LC90 values were 2.39, 7.59, and 4.14 µg cm-2 for D. variabilis, I. scapularis and R. sanguineus, respectively, but had minimal effect on A. americanum. After 48 hours exposure, the LC50 values were 4.14, 0.78, 0.79 and 0.52 µg cm-2, and LC90 values of 8.06, 1.48, 1.54 and1.22 µg cm-2 for A. americanum, D. variabilis, I. scapularis and R. sanguineus, respectively. The repellency of CWO on tick species decreased with time. The repellency and toxicity bioassays demonstrated concentration dependent responses of tick nymphs to the oil, indicating the potential of the CO2-derived cedarwood oil be developed as an eco-friendly repellent and/or acaricide.