Efficacy of chlorfenapyr (AC 303630) experimental pour-on and CyLence formulations against naturally acquired louse infestations on cattle in New York

The four chlorfenapyr formulations examined provided 100% control of both t he nymphal and adult stages of naturally acquired Bovicola bovis (L.) on ca ttle up to 35 days after application. Treatment with 6 mg chlorfenapyr per kg BW in a 0.12 mi per kg BW formulation was as effective as treatment with CyLence(TM) (cyfluthrin) in controlling naturally acquired Solenopotes cap illatus (Enderlein) on cattle for 35 days. Percent reduction was never grea ter than 90% with any chlorfenapyr application against Linognathus vituli ( L.). However, percent reduction was greater than 90% with CyLence(TM) from day 21 through 35. No adverse effects were noted on cattle from any of the chlorfenapyr dosages used. (C) 2001 Elsevier Science B.V. All rights reserv ed.