Evaluation of non-conventional treatments for control of the biting louse (Bovicola ovis) on sheep

variety of non-conventional treatments was applied to biting louse ( Bovicola ovis ) infested sheep in order to evaluate ways in which farmers could control the louse infestations and still maintain Organic Production Standards.
In one trial, louse scores of sheep shorn but kept dry or wetted by water alone or with water plus detergent were compared 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% reduction in mean louse scores. The combined effects on mean louse scores of shearing and wetting, as opposed to shearing alone, were statistically significant on two of the three farms at 32–35 days post-treatment. 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 insecticidal substances considered acceptable by Organic Production Standards, azadirachtin (neem), pyrethrum, soap, was applied to louse-infested sheep and their efficacy compared with that of a commercial formulation of cypermethrin. The sheep treated with azadirachtin and pyrethrum had significantly 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 numbers on sheep for at least 40–50 days. The lack of persistence compared with that obtained with conventional insecticides was the only apparent drawback.