Action of injectable doramectin on Haematobia irritans incattle naturally infested: results of simultaneous observations in Brazil and Argentina

摘要

A field test aiming an evaluation of the injectable doramectin on the horn-fly Haematobia irritans was carried out simultaneously in Brazil and Argentina. Both places, Eldorado do Sul, RS, Brazil and Rafaela, Santa F??, Argentina, utilized a total number of forty adult animals being twenty treated and twenty controls. Flies were counted on days 0, 1, 4, 7, 10, 14, 21, 28 and 35 post-treatment (p.t.). By comparison with control group efficacy in Brazil was less than 50% in day +1 p.t., 84.4, 72.6, 81.4, 74.2, 79.2, 50.7 and 64.7% in the subsequent days while in Argentina was 97.3, 84.2, 95.9, 92.2, 93.6, 63.3, 73.8 and 66.9% respectively. A decrease on natural population of horn-fly was observed in both places indicating a contribution of this avermectin formulation in the control of this insect although results in Brazil showed less efficacy than in Argentina.