# Populational Model of Rhipicephalus microplus in Beef Cattle in the Southern Region of Paraná, Brazil

## TL;DR

This study analyzed tick infestations in different cattle breeds in Brazil and found that certain breeds and crossbreeds are more resistant to ticks.

## Contribution

The study identifies specific cattle breeds and crossbreeds with lower tick infestation levels and proposes a strategic acaricide application method.

## Key findings

- Caracu, Canchim, and their crossbreeds showed lower tick infestations compared to Charolais and Aberdeen Angus.
- Strategic acaricide application starting in November with treatments every 21 days is recommended for effective tick control.
- Population dynamics of R. microplus were analyzed over five years in Paraná, Brazil.

## Abstract

A five-year investigation in Paraná, Brazil, examined tick populations of R. microplus on a diverse cattle herd. Tick counts were conducted biweekly to evaluate infestation levels and breed differences. Results indicated that Caracu, Canchim, and their crossbreeds exhibited lower infestations than Charolais and Aberdeen Angus. The study recommends the use of resistant breeds in conjunction with strategic applications. Enhanced host resistance and custom acaricide strategies are essential for effective management.

In order to describe the population dynamics of R. microplus in the southern region of the state of Paraná, Brazil, and to identify racial differences between hosts in the level of infestation by this parasite, the teleogins of approximately 70 males per year were counted every 14 days for 5 years. The herd comprised eight genetic groups, aged 12 to 24 months, in an area of 76 ha (60 ha of native fields and 16 ha of Hemarthria altíssima). The monthly averages of the counts per animal were analyzed using the GENMOD procedure, which accounts for the effects of genetic group, month, genetic group × month and cycle. Three generations of ticks of increasing infestation intensity were analyzed in December, February and May, respectively. Animals from Caracu and Canchim breeds as well as Charolais × Caracu and Aberdden Angus × Canchim cross-breeds had the lowest levels of infestation compared to Charolais and Aberdeen Angus. We conclude that by employing the aforementioned mixed breeds, in combination with a strategic control of initiating the application of acaricides in November, followed by two to three treatments every 21 days, this procedure represents the most effective method of controlling ticks in this region.