The efficiency of avermectins (abamectin, doramectin and ivermectin) in the control of Boophilus microplus, in artificially infested bovines kept in field conditions

Tests were performed on artificially infested bovines, kept in field conditions, to assess the efficiency of avermectins (abamectin, doramectin and ivermectin) on Boophilus microplus (Canestrini, 1887). This assessment was carried out on 40 bovines, in the Paraíba Valley, in the State of São Paulo, Brazil. These bovines were distributed into four groups (abamectin, doramectin, ivermectin and a control group), after artificial infestation with some 4000 larvae per animal on days −21, −14, −7, −1, 7 and 14. The animals from the treated groups were subcutaneously injected with the commercial avermectins, at a dose of 200 μg/kg of live weight (1 mL/50 kg). The best results were shown by the group treated with doramectin, both in relation to the reduction of female count (an average of 85.92% between 3rd and 28th day after treatment) and also in the reduction of oviposition among the females collected from the bovines after treatment and then kept in the laboratory (an average of 83.51%). None of the avermectins proved to be efficient in inhibiting the hatching of the larvae.