Effect of essential oils against acaricide\u2010susceptible and acaricide-resistant Rhipicephalus ticks

Darcy Adriann Rebonato Luns,Naftaly W Githaka,Itabajara Da Silva Vaz,Carlos Logullo,Renato Martins,Sofia Pombal,Jesus M Lopez Rodilla

doi:10.1007/s10493-021-00601-x

Abstract

The indiscriminate use of acaricides is a problem worldwide and has increased the selection of acaricide-resistant tick populations. The goal of this study was to evaluate the acaricide effects of two essential oils (from Schinus molle and Bulnesia sarmientoi) using the larval immersion test on three Rhipicephalus tick species. Rhipicephalus evertsi, Rhipicephalus appendiculatus and Rhipicephalus pulchelus ticks collected in Kenya, without history of acaricide exposure, were tested, as well as individuals from two populations of Rhipicephalus microplus (with or without history of acaricide exposure), for comparison. The sample most resistant to the treatments was a population of R. microplus with previous acaricide exposure, whereas the least tolerant sample was a strain of the same species that never had contact with acaricides (Porto Alegre strain). Interestingly, the field tick samples without previous acaricide exposure responded to essential oils with a mortality profile resembling that observed in the acaricide-resistant R. microplus field population, and not the susceptible Porto Alegre strain. The essential oil of B. sarmientoi and its two components tested (guaiol and bulnesol) caused the highest mortality rates in the tested species and are potential molecules for future studies on control methods against these species.

Highlights

Ticks are important disease vectors, affecting both human and animal populations, and transmitting a wide range of pathogens (Silva and Silva 1999; Corson et al 2004; Sonenshine and Roe 2006)
The mortality induced by guaiol was markedly different between acaricide-susceptible ticks and the field population, being effective at 0.01% against larvae from Porto Alegre strain but only at 10% concentration against field ticks (Figs. 1f and 2f)
It was observed that R. microplus ticks previously exposed to acaricides (Fig. 2) were less susceptible to treatment with essential oils and their selected compounds, whereas ticks that have never been exposed to acaricides suffered high larval mortality upon these treatments (Fig. 1)

Summary

Introduction

Ticks are important disease vectors, affecting both human and animal populations, and transmitting a wide range of pathogens (Silva and Silva 1999; Corson et al 2004; Sonenshine and Roe 2006) These arthropods cause considerable losses to the cattle industry worldwide (Grisi et al 2014). Rhipicephalus evertsi is the vector of Rickettsia africae (Hedimbi et al 2011; Walker et al 2014), whereas Rhipicephalus pulchellus transmits benign bovine theileriosis caused by Theileria taurotragi, in addition to sheep’s milk virus To humans, these ticks can transmit Rickettsia conorii, a bacterium that causes tick typhus, as well as the Crimean-Congo hemorrhagic fever virus (Walker et al 2014)

Objectives

Methods

Results

Conclusion