Suppression of Culicoides brevitarsis (Kieffer) (Diptera: Ceratopogonidae) on cattle in Queensland with deltamethrin and cypermethrin

Abstract

To reduce the risk of arbovirus transmission when cattle are transported through areas of vector activity to ports for export, we examined the efficacy of buffalo fly treatments containing deltamethrin or cypermethrin on the vector, Culicoides brevitarsis. Both chemicals significantly reduced the total numbers of C. brevitarsis on cattle from 8 h to 53 h after treatment. Deltamethrin and cypennethrin gave similar reductions in blood-feeding from 8 h and 12 h after treatment respectively. The data suggested that the chemicals' primary effects were the reduction of landing and/or the time spent on the animals by C. brevitarsis rather than any specific effect on feeding. Treatment with either deltamethrin or cypermethrin therefore reduced but did not eliminate the risk of arbovirus transmission by C. brevitarsis. The chemicals should be used in conjunction with other risk-reduction measures. Treatment of cattle 8-24 hours before their exposure to risk would be preferable to avoid a period of poor protection immediately after treatment.