Resistance by the blue tick (Boophilus decoloratus) to the synthetic pyrethroid, fenvalerate.

The Shaw larval test, in conjunction with adult tick immersion and stall tests, was utilized to confirm that a field strain of B. decoloratus, from Natal, is highly resistant to the ixodicide fenvalerate (Factor of resistance 4,744). This resistance developed over a reported 18 months of usage for cattle dipping.