In-vitro efficacy of a botanical acaricide and its active ingredients against larvae of susceptible and acaricide-resistant strains of Rhipicephalus (Boophilus) microplus Canestrini (Acari: Ixodidae)

Authors: SINGH, NIRBHAY - Guru Angad Dev Veterinary & Animal Sciences University; Miller, Robert; KLAFKE, GUILHERME - Desiderio Finamore Veterinary Research Institute (FEPAGRO); Goolsby, John; Thomas, Donald; Perez De Leon, Adalberto - Beto

Submitted to: Ticks and Tick Borne Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2017
Publication Date: 2/9/2018
Citation: Singh, N.K., Miller, R., Klafke, G., Goolsby, J., Thomas, D.B., Perez De Leon, A.A. 2018. In-vitro efficacy of a botanical acaricide and its active ingredients against larvae of susceptible and acaricide-resistant strains of Rhipicephalus (Boophilus) microplus Canestrini (Acari: Ixodidae). Ticks and Tick Borne Diseases. 9(2):201-206.

Interpretive Summary: Ticks and tick-borne diseases are a major constraint for the sustainable cattle industry in the tropical and subtropical regions of the world. Presently, chemical acaricides are the most widely used tick control strategy but it has several disadvantages including resistance development, environmental pollution and residual effects. Herbal acaricides using plant products and their combinations would be an eco-friendly tick control alternative. The acaricidal efficacy of Essentria® IC-3, an insect concentrate for crawling and flying insect pests and its active components was evaluated against acaricide resistant and susceptible cattle tick populations. The results will benefit the farmers, ranchers, dairy and beef industry by providing totally natural alternative to chemical acaricides for effective control of cattle fever ticks Rhipicephalus microplus and Rhipicephalus annulatus. It can also be used to complement existing control strategies for ticks in the transboundary region between Mexico and Texas, particularly against the alternative host species such as nilgai and white-tailed deer where chemical acaricides can not be used due to its residual effect.

Technical Abstract: Ticks and tick-borne diseases are a major constraint for the sustainable cattle industry in the tropical and subtropical regions of the world. The developments of resistance to most of the commonly used acaricides lead to an attempt to screen herbal products for their possible acaricidal activity to develop an eco-friendly tick control alternative. Botanical acaricide, Essentria® IC-3 insect concentrate contains rosemary oil (10%), geraniol (5%) and peppermint oil (2%), and acts on target pests by octopamine blocker technology. Essentria® IC-3 and its active components were evaluated for acaricidal activity against several acaricide resistant and susceptible strains of cattle tick, Rhipicephalus (Boophilus) microplus by Larval Packet test (LPT) using 14-21 days old unfed larvae. The efficacy was assessed by measuring percent larval mortality and estimating lethal concentrations at 50% (LC50) and 95% (LC95) with 95% confidence limits (CL) using probit analysis. The LC50 and LC95 (95% CL) values for Essentria® IC-3 against the susceptible strain was estimated as 0.647% (0.59 to 0.69) and 1.033% (0.94 to 1.19), respectively, whereas, LC50 and LC95 values for other strain were variable ranging from 0.597-1.674% and 0.927-2.236%, respectively. Among the various active ingredients, all acaricidal property of Essentria® IC-3 seems to be attributed to geraniol as other failed to exhibit any such response and its LC50 and LC95 (95% CL) values for the Deutch strain were estimated as 0.656% (0.61 to 0.69) and 1.114% (1.03 to 1.25), respectively. The comparison of LC50 and LC95 values of all strain with the susceptible (Deutch) showed susceptibility comparable to Deutch against geraniol except for Las Palmas strain. We report a low level of resistance in some of the acaricide resistant strains against a herbal acaricide in cattle tick for the first time, possibly due to cross-resistance to chemical acaricdes.