Abstract

Biological control agents are possibly the best alternative to agrochemicals for the control of livestock nematodes. Strains of Bacillus thuringiensis (Bt) and Clonostachys rosea were isolated from grazing pastures collected from pens of livestock. A total of 25 isolates of B. thuringiensis and 10 of C. rosea were successfully isolated. In vitro studies were conducted to determine the efficacy of B. thuringiensis (Bt) and C. rosea isolates as biological control agents against sheep nematodes. All of Bt and C. rosea reduced nematode counts considerably. Isolates of Bt and C. rosea reduced nematodes counts by 28.5 to 62% and 44 to 69.9%, respectively, in the faeces bioassay. In the water bioassay nematode count reductions of 62 to 85% and 62.7 to 89.3% by Bt and C. rosea, respectively, were observed. Majority of the best nematode-killing isolates were from a goat grazing pasture. Both biocontrol agents showed capability to reduce nematode counts in this study.

Key words: Anthelmintics drugs, Bacillus thuringiensis, biological control agents, Clonostachys rosea, livestock.