Evaluation of diazinon and ivermectin efficacy for the control of horn-fly (Haematobia irritans) on grazing cattle in Tuxpan, Veracuz, Mexico.

Efficacy of 21.4% diazinon ear tags (one tag per animal), and injected ivermectin 1% (1 ml/50 kg weight, equivalent to 200 µg/kg,) for the control of horn-fly was evaluated under field conditions at a cattle-producing unit in Tuxpan, Veracruz, Mexico, for three months in 1999, Pastures used were different in their ability to provide forage to the grazing cattle, thus preventing direct comparisons of five-weight gain of steers between groups and with the control Fly counting was performed every 10 days. Diazinon 21.4% ear tags provided >87% control as assessed only on days 30, 50, 60, 70 and 90. Fly reduction of >90% was observed for injected ivermectin as determined for evaluations on the same days. There were no statistically significant differences in efficacy between the two pesticides. [ABSTRACT FROM AUTHOR]