Atividade adulticida e larvicida da eprinomectina injetável sobre Haematobia irritans

Abstract

The aim of this study was to evaluate the action of injectable eprinomectin in the control of Haematobia irritans in cattle and their larvicidal activity to prevent the emergence of adult horn fly in the feces of treated animals. Thirty bovines of taurine and zebu breeds were used. The animals were divided as follows: 10 animals in the control group and 20 animals in the treated group. Treatment was performed on day 0 using injectable eprinomectin 1% at the dose of 200 μg / kg of body weight, equivalent to 1mL / 50 kg of weight by subcutaneous route. The quantification of flies in the cattle occurs on days 7 and -1 before treatment and +3, +7, +17, +21, +31, +35 and +45 after treatment. The incubations with eggs of horn flies were also performed in the faeces of control and treated groups on days +3, +7, +17, +21, +31, +35 and +45 after treatment. Fifteen grams of the substrate from each fecal sample were placed in 100 ml plastic cups. In each sample, a square of filter paper measuring 4,0 cm 2 containing 30 eggs was placed on the substrate. The samples from the control and treated groups were conditioned in biochemical oxygen demand (BOD) at 27oC and 80% humidity. After eight days of incubation, pupae recovery was carried out, transferred to Petri dishes and reconditioned in BOD. The administration of 1% eprinomectin presented adulticide efficacy results of 91.15% for day 3; 92.63% for day 7; 74.67% by day 17; 71.61% for day 21; 55.80% for day 31; 46.79% for day 35 and 49.86% for day 45. The larvicidal efficacy was found to be 100% by day 3; 100% for day 7; 98.98% for day 17; 93.60% for day 21; 74.07% by day 31; 39.80% for day 35 and 22.55% for day 45. The study demonstrated that injectable eprinomectin 1% was effective in control of the horn flies in cattle and in stopped the evolution of the immature stages of H. irritans in dung substrate with eprinomectin residue.