Cypermethrin and ivermectin resistance in field populations of Rhipicephalus sanguineus sensu lato (Latrielle, 1806) collected from dogs in south India.

Prathyusha Sunkara,Sudhakar Krovvidi,Sreedevi Chennuru,Jyothisree Chitichoti

doi:10.1007/s11259-021-09830-2

Prathyusha Sunkara, Sudhakar Krovvidi + Show 2 more

Open Access

https://doi.org/10.1007/s11259-021-09830-2

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Abstract

The abuse of acaricides for control of Rhipicephalus sanguineus sensu lato ticks led to a strong selection pressure for acaricide resistance. Data on acaricide resistance in R. sanguineus s.l. populations from India is meager though veterinarians frequently report treatment failures. The present study was aimed to characterize the level of resistance in R. sanguineus s.l. against most commonly used drugs, cypermethrin and ivermectin in Andhra Pradesh, south India. Fourteen adult female tick populations were collected from naturally infested dogs at veterinary clinics, residence and stray dog in nine state municipal corporations/municipalities. Information on the history of dog treatment with acaricides was obtained by interviewing dog owners. The larval packet test (LPT) and larval immersion test (LIT) were used on the larvae of ticks to test for resistance to cypermethrin and ivermectin, respectively. Mortality data of each tick population was analyzed by probit analysis. Corresponding to the most susceptible population, thirteen (92.6%) and six (42.9%) tick populations were regarded as resistant to cypermethrin and ivermectin, respectively. The phenotypic level of cypermethrin (resistance ratios at LC50% varied from 1.55 to 13.29) and ivermectin (resistance ratios at LC50% ranged from 1.16 to 4.79) resistance varied distinctly between the populations. Additionally, all the populations were tested using PCR to demonstrate the frequency of the point mutation in sodium channel gene that corresponds with resistance of R. sanguineus s.l. to cypermethrin. A nucleotide substitution (T2134C) on domain III segment VI of the sodium channel gene was noticed in phenotypically resistant tick populations on DNA sequencing. Ivermectin resistance in the brown dog ticks is reported for the first time from India.

Highlights

Rhipicephalus sanguineus sensu lato (Latrielle 1806), the brown dog tick, is a three-host tick that feeds principally on dogs and infrequently humans, and transmits various pathogens of veterinary and public health importance
Results of larval packet test (LPT) with cypermethrin against R. sanguineus s.l. populations collected from Andhra Pradesh, India
MTM2 ticks were collected from dog at veterinary clinic, which had been treated with commercial pet shampoo weekly for three weeks before sampling

Summary

Introduction

Rhipicephalus sanguineus sensu lato (Latrielle 1806), the brown dog tick, is a three-host tick that feeds principally on dogs and infrequently humans, and transmits various pathogens of veterinary and public health importance. Rhipicephalus sanguineus are generally controlled using topical (oranophosphates, synthetic pyrethroids and amidines) and systemic (macrocyclic lctones) acaricides to infested hosts and some times in the surroundings. This confined genetic exchange together with prolonged use and abuse of acaricides contributed favourable circumstances for selection of acaricide resistant populations. Acaricide resistance in the brown dog ticks, R. sanguineus has been reported (Rodriguez-Vivas et al 2017a; Becker et al 2015)

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