Selective control of Rhipicephalus (Boophilus) microplus in fipronil-treated cattle raised on natural pastures in Lages, State of Santa Catarina, Brazil

Abstract

An examination of a selective control of Rhipicephalus (Boophilus) microplus and consequent cost reduction was carried out in two areas of native pasture in the municipality of Lages, State of Santa Catarina, Southern Brazil, from May 2007 to April 2009. Forty cattle were divided into two groups of 20 animals each (conventional and selective control groups). At 14-day intervals female ticks larger than 4.5 mm found on the right flank of cattle bodies were counted, and these results multiplied by two. Fipronil 1 mg.kg -1 pour on was then administered for tick control. In the conventional group all the cattle were treated when tick count averaged more than 40 female ticks per animal while in the selective group only animals parasitized by more than 40 ticks were treated with acaricide. Every 28 days the cattle's weight was checked for cost-effective analysis. The conventional group required an additional 20 doses of fipronil compared with the selective one. There was no statistically significant differences regarding weight gain in both groups.Keywords: Rhipicephalus (Boophilus) microplus, cattle, fipronil, selective control, conventional control. ResumoCom o objetivo de avaliar o método de controle seletivo do Rhipicephalus (Boophilus) microplus e reduzir os custos para o controle, de maio de 2007 a abril de 2009, em duas invernadas de campo nativo no município de Lages, SC, utilizaram-se 40 bovinos que foram divididos em dois grupos (convencional e seletivo), de 20 animais cada. A cada 14 dias foi realizada a contagem das fêmeas maiores ou igual a 4,5 mm, no lado direito do corpo dos animais, e o valor obtido, multiplicado por dois. Foi utilizado fipronil 1 mg.kg -1 pour on para o controle de carrapatos. No grupo convencional, foram tratados todos os bovinos quando a média do grupo foi igual ou superior a 40 fêmeas e no grupo seletivo, foram tratados apenas os animais que apresentaram uma infestação igual ou superior a 40. A cada 28 dias foi realizada a pesagem dos animais para análise da relação custo/benefício. Foram realizadas 20 aplicações a mais do carrapaticida no grupo convencional em relação ao seletivo. Não houve diferença estatística entre o ganho de peso do grupo convencional em relação ao grupo seletivo.Palavras-chave: Rhipicephalus (Boophilus) microplus, bovino, fipronil, controle seletivo, controle convencional.

Climate conditions associated with the occurrence of pyrethroid residues in bulk milk tank

“…These facts strengthen our hypothesis that climate conditions influence the detection of pyrethroid residues in bulk milk tank probably as a result of the subjective use of pyrethroids mainly based on observation of infestation levels (Rocha et al, 2012) and the influence of climate conditions on infestation by ectoparasites (Estrada-Peña et al, 2006;Paim et al, 2011). With this in mind, Souza et al, (1988) described that lower infestation levels of Rhipicephaus (Boophilus) microplus, the major ectoparasite in cattle (Raynal et al, 2013), occurred during months (i.e.…”

“…Regarding the time period that was selected, this study was initiated in the dry period and finished in the rainy period, which resulted in great variability in climate conditions. This is representative of typical annual climate conditions that have been previously recorded based on official records of the Meteorological Center of the Minas Gerais State (Base…, 2011;Picinin et al, 2013). In the present study, a milk sample was assumed to be positive if any analytical residue was detected, regardless of the drug concentration.…”

“…For this reason, data on climate influences in pyrethroid residues in raw milk are of great relevance, particularly in tropical climate countries as Brazil, where different conditions of rainfall, relative humidity and temperature are perceived on unequable basis (Picinin et al, 2013). Thus, the present study aimed to identify the climate condition parameters that were associated with the occurrence of pyrethroids residues in bulk milk tank using a multivariate principal component analysis.…”

“…Thus, considering that climate conditions influence infestation by insects and ticks, such as horn flies (Haematobia irritans) and Rhipicephalus (Boophilus) microplus (Souza et al, 1988;Barros, 2001;Estrada-Peña et al, 2006;Paim et al, 2011), and the fact that the use of pyrethroids is mainly based on the subjective observation of infestation levels (Rocha et al, 2012), it was hypothesized that some climate condition parameters were associated with the occurrence of pyrethroid residues in bulk milk tank. For this reason, data on climate influences in pyrethroid residues in raw milk are of great relevance, particularly in tropical climate countries as Brazil, where different conditions of rainfall, relative humidity and temperature are perceived on unequable basis (Picinin et al, 2013).…”

Acaricidal efficacy of topical formulation of fipronil in naturally infested dogs in Amazonic region, Brazil

“…In Brazil, several studies have described the therapeutic efficacy in dogs and other species naturally and experimentally infested with ticks and fleas (TANCREDI et al, 2009;PAIM et al, 2011), but no studies have tested the efficacy of Fipronil in dogs in the particular conditions of the Amazon region climate. It is necessary to emphasize that the natural feature of the Rainforest, characterized by heavy rainfall, can affect the efficiency of topical formulations on the control of ticks' populations (GROSSCURT, 1993).…”