Evaluation of the in vitro acaricidal effect of five organic compounds on the cattle fever tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Authors: OLIVA-CHAVEZ, ADELA - Texas A&M University; GUZMAN-VALENCIA, STEPHANIE - Texas A&M University; LYNN, GEOFFREY - Texas A&M University; AROCHO-ROSARIO, CHARLUZ - Texas A&M University; Thomas, Donald; JOHNSON, TAMMI - Texas A&M University

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2023
Publication Date: 4/13/2023
Citation: Oliva-Chavez, A., Guzman-Valencia, S., Lynn, G., Arocho-Rosario, C., Thomas, D.B., Johnson, T.L. 2023. Evaluation of the in vitro acaricidal effect of five organic compounds on the cattle fever tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae). Parasites & Vectors. https://doi.org/10.1007/s10493-023-00780-9.
DOI: https://doi.org/10.1007/s10493-023-00780-9

Interpretive Summary: Five organic compounds (Nootkatone, Stop the Bites®, BioUD®, lavender oil, and cedarwood oil) to control and repel ticks were evaluated using laboratory tests for mortality and repellency. The levels of control of adult females by reducing the reproduction of egg hatch indicate that only Nootkatone, Stop the Bites®, and BioUD® may significantly decrease tick populations above 90%. The results from the immersion tests indicate that four of the organic compounds (Nootkashield™, Stop the Bites®, BioUD®, and cedarwood oil had potent acaricidal activity in which low concentrations killed more than 90%. By comparison, only a high concentration of lavender oil (7.45%) killed 90%. Additionally, Nootkashield™, Stop the Bites®, and BioUD® had strong repellent properties with over 90% repellency at the two highest concentrations tested. Lavender and cedarwood oil were less repellent at the highest concentration with a percentage of repellency of 66.67% and 86.67% at 10% concentration, respectively. The evaluation of the effectiveness of these organic compounds indicate that only Nootkatone, Stop the Bites®, and BioUD® may significantly control tick populations, highlighting their potential as safe alternative acaricides for the control of cattle fever ticks.

Technical Abstract: The efficacy of five organic compounds (Nootkatone, Stop the Bites®, BioUD®, lavender oil, and cedarwood oil) to control and repel ticks in vitro was evaluated using Larval Immersion Tests (LITs), repellency assays, and Adult Immersion Tests (AITs). Different concentrations were assessed during the LIT to determine the LC50 and LC90 through Probit Polo analysis. The differences in repellency were evaluated after 30 min and significance was determined by One-way ANOVA followed by Dunnett test for multiple comparisons, comparing each compound to the blank (P<0.05). The levels of control of adult females were defined with Drummond’s equation. The results from the Larval Immersion Tests (LITs) indicate that four of the organic compounds (Nootkashield™, Stop the Bites®, BioUD®, and cedarwood oil) had potent acaricidal activity on R. microplus larvae with LC90 of 0.56%, 0.03%, 0.06%, and 0.83%, respectively. By comparison, the LC90 for lavender oil was 7.45%. Similarly, Nootkashield™, Stop the Bites®, and BioUD® had strong repellent properties with over 90% repellency at the two highest concentrations tested. Lavender and cedarwood oil were less repellent at the highest concentration with a percentage of repellency of 66.67% and 86.67% at 10% concentration, respectively. The evaluation of the effectiveness of these organic compounds on reducing the reproduction of R. microplus indicate that only Nootkatone, Stop the Bites®, and BioUD® may significantly decrease tick populations (Drummond’s index above 90%). Hence, Nootkashield™, Stop the Bites®, and BioUD® have strong acaricidal and repellent effects on R. microplus larvae and significantly affect the reproduction of R. microplus females, highlighting their potential as alternative acaricides for the control of cattle fever ticks.