EFFICACY OF SOME INDIGENOUS MEDICINAL PLANTS TO CONTROL ANTINEMATICIDAL-RESISTANT HAEMONCHUS CONTORTUS IN SHEEP

Abstract

Antinematicidal resistance has been arising among the gastrointestinal nematodes, primarily Haemonchus (H.) contortus in small ruminants to the commercialized broad- spectrum synthetic chemotherapeutics in Pakistan and other countries of the world. Therefore, the current study, which was carried out on the Karakul breed of sheep in Angora Goat Farm - Rakh Khairewala, Layyah District (Pakistan) , began with the intention of finding out the rampancy of resistance among H. contortus populations in addition to assessing some native medicinal plant extracts for their potency to control the resistant parasite. The experimental animals were allocated to 16 groups (n=15) followed by the demonstration of haemonchosis percentage (˃90%) among other nematodiasis. Three groups were allotted for detection of resistance towards oxfendazole (OXF), levamisole (LEV) HCL and ivermectin (IVM) plus one group for control. The faecal egg count reduction test (FECRT) revealed prevalence of resistance to the above drugs with varying levels. Pursuant to the RESO Computer Programme, the calculated FECR% was -56, 75 and78, whilst the lower confidence interval was -311, 38 and 42 for OXF, LEV and IVM, respectively. The LC50 value for oxfendazole, estimated via probit analysis, was 1.86 μg ml‫ 1 ־‬after performing egg hatch assay (EHA). For studies on phytotherapeutics, 12 groups (n=15) were allotted. However, the same control group was used because, statistically, all the groups are located within the same population. The calculated FECR% for effective crude aqueous-methanol extracts of the tested plants was 94.59, 88.6, 87.5, 85.81 and 85.14 for combined Nicotiana (N.) tabacum leaves and Azadirachta (A.) indica seed kernels, high dose of N. tabacum, low dose of N. tabacum, high dose of combined N. tabacum and Vernonia (V.) anthelmintica seeds, and A. indica, respectively. LC50 values, determined through probit analysis after conducting EHA, were 0.523, 0.566, 1.169, 1.217, 3.138, and 5.95 μg ml‫ 1 ־‬for combined N. tabacum and A. indica, N. tabacum, A. indica, combined N. tabacum and V. anthelmintica, combined V. anthelmintica and A. indica, and V. anthelmintica respectively. The adult motility test revealed high adulticidal potency of solitary N. tabacum and combined N. tabacum and A. indica which killed 100% of worms after six hours of exposure at the concentration of 25 mg ml‫ ,1 ־‬whilst the others were less effective. No synergy, additive effect and antagonism were observed.