EVALUATION OF NONCONVENTIONAL TREATMENTS FOR CONTROL OF THE BITING LOUSE (BOVICOLA-OVIS) ON SHEEP

A variety of non-conventional treatments was applied to biting louse ( Bovicola ovis) infested sheep in order to evaluate ways in which farme rs could control the louse infestations and still maintain Organic Pro duction Standards. In one trial, louse scores of sheep shorn but kept dry or wetted by water alone or with water plus detergent were compare d with unshorn sheep treated similarly. Shearing alone accounted for a 35.7-66.3% reduction in mean louse scores. Wetting alone either with water or with water and added detergent accounted for a 26.9-35.3% red uction in mean louse scores. The combined effects on mean louse scores of shearing and wetting, as opposed to shearing alone, were statistic ally significant on two of the three farms at 32-35 days post-treatmen t. The effects persisted for the duration of the trial (between 48 and 52 days), at which point shearing and wetting with detergent provided 95.3-99.6% control of lice. In a second trial, a range of insecticida l substances considered acceptable by Organic Production Standards, az adirachtin (neem), pyrethrum, soap, was applied to louse-infested shee p and their efficacy compared with that of a commercial formulation of cypermethrin. The sheep treated with azadirachtin and pyrethrum had s ignificantly fewer lice than either the control or soap treated sheep over the 48 days of the trial. Neither azadirachtin nor pyrethrum were significantly less effective than cypermethrin. Control (reduction in louse score) of 85.0-100% was achieved over the period of the trial. It is concluded that most of the non-conventional treatments evaluated had a useful and cost-effective role to play in reducing louse number s on sheep for at least 40-50 days. The lack of persistence compared w ith that obtained with conventional insecticides was the only apparent drawback.