Objectives:

To determine the effectiveness of acaricides in field populations of Rhipicephalus (Boophilus) microplus collected in cattle farms in the municipalities of Ibagué, Espinal and Cajamarca, department of Tolima.

Methodology:

A total of 1200 teleogines of R. microplus were collected in 12 farms and subjected to a modified adult immersion test (AIT) in order to evaluate four commonly used acaricides in the region: cypermethrin 15%, amitraz 20.8 %, 84% ethion and 1% ivermectin. Parameters such as reproductive efficiency and hatching percentage were calculated, with which the efficacy of each acaricide was determined.

Results:

It was found that in 91.66% of the farms evaluated the populations of R. microplus were resistant to cypermethrin, 91.66% to amitraz, 75% to ethion and 66.66% to ivermectin, showing loss of efficacy of these chemicals.

Conclusion:

The high dispersion of resistance to the acaricides frequently used in the field for the control of populations of R. microplus in three municipalities of Tolima was demonstrated, denoting the need to establish new control strategies that allow limiting infestations of the common cattle tick.

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