In vivo effect of diflubenzuron, administered via mineral salt supplementation, against Haematobia irritans and Rhipicephalus microplus parasitizing cattle

Abstract

This study involved two field trials with the aim of evaluating the efficacy of diflubenzuron, via mineral supplementation, against Haematobia irritans parasitizing cattle. Concomitantly with the main trial, a stall test was conducted to ascertain the effects of a different formulation with the same active ingredient against Rhipicephalus microplus, along with the action of diflubenzuron on the reproductive parameters of R. microplusfemales that had naturally detached from cattle. Against H. irritans, it was observed that the efficacy indexes fordiflubenzuron were low (≤ 31.3% or 44.6%) or null (0.0%) throughout the study. The anti- R. microplus efficacy of diflubenzuron, at weekly intervals, ranged from 0.0 to 13.7% over the entire experimental period. Null efficacy (0.0%) was registered for diflubenzuron in relation to the reproductive parameters of R. microplusfemales that had naturally detached from cattle. The different diflubenzuron formulations, administered via mineral salt supplementation, did not show satisfactory efficacy indexes against H. irritans and R. microplus parasitizing cattle, within the experimental design of the present study. In addition, this agent did not present any deleterious effects on the reproductive parameters of R. microplus females.

First report of the efficacy of a fluralaner-based pour-on product (Exzolt® 5%) against ectoparasites infesting cattle in Brazil

“…There are reports of increased prevalence of R. microplus populations that are resistant to different chemical classes of insecticides, such as the amidines, macrocyclic lactones, phenylpyrazoles and benzophenylurea [ 5 , 47 – 55 ]. It is apparent from the published literature that R. microplus populations in those regions where studies with Exzolt were conducted were resistant to amitraz (250 ppm) [ 56 , 57 ], abamectin and ivermectin 500 µg/kg BW pour-on, ivermectin 200 and 630 µg/kg BW injectable [ 58 – 60 ], fipronil 1 mg/mg pour-on [ 37 ], fluazuron 1.6 mg/kg + ivermectin 630 µg/kg (injectable) and diflubenzuron with 17 g of product added per kilogram of mineral salt [ 61 , 62 ]. The studies reported here may indicate the effectiveness of Exzolt in ticks resistant to above-mentioned parasiticides.…”