Effect of Urea Solution on Haemonchus contortus Inoculum from Intact Faecal Pellets or L3 Larvae

Abstract

Internal parasites cause severe economic losses to the sheep industry globally. Of particular concern is Haemonchus contortus; a parasite widely resistant to synthetic anthelmintics and prevalent in the warm wet environments of the tropics. The ovicidal and larvicidal properties of urea solution were investigated in pot trials using Batiki grass (Ischaemum aristatum var. indicum) inoculated with either intact faecal pellets containing approximately 10,000 eggs or 10,000 infective stage larvae. Urea solution at 5% concentration was sprayed once onto grass on the day of deposition for pellets and after a 48 hour adaptation period for infective stage larvae. Foliage and soil (inclusive of faecal pellets) were sampled separately for the presence of infective stage larvae. Urea significantly reduced larval populations from foliage for both pellet (P = 0.0015) and infective stage larvae (P = 0.0034) inoculums at P = 0.05. Urea did not significantly reduce larval populations from soil of pellet inoculated pots (P = 0.4055) but did from pots inoculated with infective stage larvae (P = 0.0488). Urea did not significantly reduce cumulative larval populations in pots inoculated with intact faecal pellets (P = 0.1070) but significantly reduced cumulative larval populations from pots inoculated with infective stage larvae (P = 0.0079). Urea solution at 5% is effective in reducing infective stage larvae from foliage. Application rate is a factor in its efficacy against Haemonchus contortus.