Effect of acaricide control of Amblyomma variegatum ticks on bovine dermatophilosis on nevis.

A sentinel group of 8 Bos taurus cattle was compared with similar cattle in a herd of 90 of which 21 were pastured with the sentinels. The sentinel group was not treated with acaricide whilst the rest of the cattle were treated weekly with the organophosphate acaricide ethion. Weekly counts of adult ticks and rankings of dermatophilosis were made on the sentinel herd. The remaining cattle were observed for the presence of ticks and dermatophilosis prior to the weekly treatment with acaricide. All sentinel cattle became infested with Amblyomma variegatum ticks and dermatophilosis developed on all. Rank correlations of tick numbers and dermatophilosis scores were between +0.34 and +0.98, varying with maturity of cattle and time during the trial. Incidence of dermatophilosis on the cattle treated with acaricide was very low. Tick numbers on the sentinel animals were compared to rainfall and temperature. It is concluded that acaricide is the best option for controlling bovine dermatophilosis in Nevis.