Eficácia de acaricidas comerciais sobre fêmeas ingurgitadas de Rhipicephalus (boophilus) microplus in vitro

Abstract

The tick Rhipicephalus (Boophilus) microplus is considered the main ectoparasite of cattle, being responsible for large losses in Brazilian cattle. Its infestation in the herd causes high direct and indirect economic losses, such as blood spoliation and its consequences such as: anemia, irritation, predisposition to stinging, leather devaluation, weight loss, decrease in meat and milk productivity and transmission of causative agents. of diseases such as bovine parasitic sadness. The most commonly used control method is chemical, made by administering ticks, which if used correctly are economically viable and effective. However, indiscriminate use can lead to selection of resistant tick populations, making them difficult to control. For this reason, it is extremely important to study the real situation of efficiency and action of acaricides before choosing the product to be used in a property. Thus, the aim of this study was to evaluate the in vitro efficacy of amitraz, dichlorvós and dichlorvos + chlorfenvinfós acaricides on R. microplus females in Cruz das Almas-BA. For the bioassay, ticks were collected from naturally infested cattle without prior contact with ticks for 60 days. The ticks were diluted according to the manufacturers recommendation and their efficacy was evaluated by the adult immersion test, where each group of 10 females were immersed for five minutes in the respective treatments. In addition to the treated groups, a negative control was also performed, whose females were immersed in distilled water. After immersion, the teleogins were fixed in Petri dishes and kept in a climate chamber at 26 ± 1 ° C and U.R. ≥ 60%, to evaluate mortality and reproductive parameters. From the bioassay it was found that the ticks based on a combination of Dichlorvos + Chlorfenvinphos and Dichlorvos were more effective on the R. microplus tick population in Cruz das Almas-Ba. Regarding the effects on tick, the combination of Dichlorvós + Clorfenvinfós was able to kill the teleogens obtaining 100% control percentage, while the dichlorvós acted preventing larval hatching obtaining 99.9%. Already the product based on amitraz did not promote recommended efficacy (95%) according to the Ministério da Agricultura, Pecuária e abastecimento, for R. microplus, providing 90.2%, demonstrating that the population tested has resistance to this drug.