Effects of fluazuron on the biological parameters of engorged females of Rhipicephalus microplus

Jairo Pinheiro,Jaqueline Rodrigues De Almeida Valim,Isabele Da Costa Angelo,Adivaldo Henrique Da Fonseca,Vania Rita Elias Pinheiro Bittencourt,Bruna De Azevedo Baêta,Fabrício Nascimento Gaudêncio,Matheus Dias Cordeiro

doi:10.29374/2527-2179.bjvm023017

Jairo Pinheiro, Jaqueline Rodrigues De Almeida Valim + Show 6 more

Open Access

https://doi.org/10.29374/2527-2179.bjvm023017

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Abstract

The objective of this study was to evaluate the biological parameters of Rhipicephalus microplus engorged females exposed to the arthropod growth regulator fluazuron. A commercial formulation based on fluazuron (Acatak®, Novartis) was administered topically to stabled cattle artificially infested with R. microplus larvae. The infestations occurred on four alternate days (days -21, -17, -13 and -6) taking as day 0 (zero) the day of treatment with a single dose of fluazuron for the treated group. Fifteen engorged females from each group were collected from the floor of the stalls at the end of the engorgement period (21 days) on pre-established days: before (day 0) and after treatment (days 4, 8 and 15), respectively. After cleaning and preparation of the engorged females in the laboratory, the following biological parameters were analyzed: weight of the engorged female, weight of the female after laying (spent female), laying period, weight of the posture, egg production index, reproductive efficiency index, hatching percentage, and nutritional index. The average weight of engorged females showed a significant reduction on all days after treatment in the exposed group. Aside from the weight after laying, all other biological parameters showed a significant reduction on the eighth post-treatment day due to exposure to fluazuron. Knowledge of the effects of an active principle on biological parameters in a population of ticks is essential for appropriate implementation of integrated management practices for parasite control.

Highlights

The tick Rhipicephalus microplus (Canestrini, 1887), known as the cattle tick, is native to Asia but has been introduced in most tropical and subtropical countries by the importation of cattle (Pereira et al, 2008)
Because of the importance of chitin synthesis for adequate development of ticks during their life cycle, especially for larval hatching, the objective of this study was to assess possible changes in the biological parameters of R. microplus females fed on calves exposed to the arthropod growth regulator fluazuron
Differences were noted between the control and exposed groups regarding the morphology of the engorged females, mainly on the 8th and 15th days after treatment (DAT) (Figure 2)

Summary

Introduction

The tick Rhipicephalus microplus (Canestrini, 1887), known as the cattle tick, is native to Asia but has been introduced in most tropical and subtropical countries by the importation of cattle (Pereira et al, 2008). The exoskeleton of ticks is similar to that of other arthropods, serving as primary protection against water loss along with mechanical protection against other sources of damage (Sonenshine, 1991). The nature of the exoskeleton is closely associated with the ticks’ growth, respiration, and locomotion. Knowledge of these aspects is necessary to develop chemical products able to penetrate the tegument and kill the ticks (Klowden, 2007). Its synthesis involves multiple cell activities, starting with biotransformation of simple metabolites and culminating with a polymer released by the cell membrane (Cohen, 1987)

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