Abstract
The Rhipicephalus (Boophilus) microplus tick is responsible for considerable economic losses in Brazil, causing leather damage, weight loss and reduced milk production in cattle and results in the transmission of pathogens. Currently, the main method for controlling this tick is using acaricides, but their indiscriminate use is one of the major causes of resistance dissemination. In this study, the adult immersion test (AIT) was used to evaluate resistance in ticks from 28 properties located in five different states (Mato Grosso do Sul, Mato Grosso, Ceará, São Paulo, e Minas Gerais) and the Distrito Federal (DF) of Brazil. The resistance was found in 47.64% of the repetitions demonstrating an efficacy of less than 90% in various locations throughout the country. The larvae packet test was used to evaluate samples from ten properties in four states (Mato Grosso do Sul, Mato Grosso, Minas Gerais and Espírito Santo). Spray products belonging to the main classes of acaricides, including combination formulations, were used in both types of test. New cases of resistance were found on properties within the states of Ceará, Espírito Santo and Mato Grosso, where such resistance was not previously reported.
Highlights
It is estimated that Brazil has approximately 212.8 million bovines and exports approximately 1,5 million tons of carcass annually, thereby holding second place in world-wide meat production (Gazeta Santa Cruz, 2014) and fifth place in milk production (FAO, 2015)
The adult immersion test (AIT) was used to evaluate resistance in ticks from 28 properties located in five different states (Mato Grosso do Sul, Mato Grosso, Ceará, São Paulo, e Minas Gerais) and the Distrito Federal (DF) of Brazil
Adult Immersion Tests (AIT) using samples from 28 properties located in five states: Mato Grosso do Sul (MS), Mato Grosso (MT), Ceará (CE), São Paulo (SP), Minas Gerais (MG) and the Distrito Federal (DF) were conducted
Summary
It is estimated that Brazil has approximately 212.8 million bovines and exports approximately 1,5 million tons of carcass annually, thereby holding second place in world-wide meat production (Gazeta Santa Cruz, 2014) and fifth place in milk production (FAO, 2015). According to Grisi et al (2014), the annual losses in Brazil due to this tick are estimated to be 3.24 billion US dollars. According to Gomes et al (2011), in addition to reducing meat and milk production, the skin lesions caused by tick infestation affect leather prices and contribute to the development of myiasis. This ectoparasite has been associated with the transmission of pathogens, such as Babesia bovis, B. bigemina and Anaplasma marginale (Bovine Babesiosis and Anaplasmosis Complex). Each class has a different mechanism of action, but the efficacy of each of them is susceptible to the development of resistant tick populations. Resistance is defined as “the ability of a parasite strain to survive and/or to multiply despite the administration and absorption of a drug given in doses equal to or higher than those usually recommended but within the limits of tolerance of the subject” (WHO, 1965)
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