In Vitro and in Vivo Efficacy of an Experimental Compound against Rhipicephalus (Boophilus) microplus Ticks

The aim of the present study was to evaluate the ixodicide efficacy of the experimental compound 712-BF-016 against Rhipicephalus (Boophilus) microplus ticks in vitro and in cattle. The in vitro efficacy was initially tested against R. Boophilus microplus larvae using the Larval Packet Test (LPT). In a 2nd study the ixodicide efficacy was tested against adult ticks using the Adult Inmersion Test (AIT). Finally, a field test with the compound was carried out using 24 steers experimentally infested with R. (Boophilus) microplus ticks which were divided into 4 groups of 6 animals each for treatment. Groups 1 and 2 received the experimental compound at concentrations of 16% and 20%, respectively, which were applied as an aspersion in a total volume of 4 liters/animal. Group 3 was equally treated but with a commercial ixodicide containing cipermethrin at a 16% concentration. Group 4 served as untreated control. The efficacy was measured on days 1, 2, 3 after treatment as the percentage of ticks present from the treated groups, relative to the ticks present in the untreated control. The results indicated a percentage mortality of 93.21% for LPT and 98.02% for AIT. The efficacy produced in cattle was 61.78%, 76.43% and 85.34% for groups 1, 2 y 3, respectively. It is concluded that there was no concordance between the results obtained in vitro with those found in cattle. Possibly the excipient used for the formulation of the experimental compound was not suitable and had some influence on the results.