Abstract
Background:
Haemonchosis remains a major constraint in small ruminant production due to reduced productivity. In tropical regions, it is estimated that haemonchosis can cause significant economic losses in livestock, with prevalence rates often exceeding 50% in some areas.

Aim:
This study aimed to assess and compare the in vitro anthelmintic activity of aqueous and ethanolic extracts of wulung coconut husk against Haemonchus contortus, by evaluating the phytochemical profile, adult worm mortality test, and surface morphological changes observed using a scanning electron microscope (SEM).

Methods:
Coconut were collected from Kulon Progo Regency, Yogyakarta, Indonesia. Phytochemical screening was conducted to identify bioactive compounds. Each treatment group consisted of five adult female worms with four replicates, and adult worm mortality was evaluated at final concentrations of 1%, 4%, 7%, and 10%. Mortality was recorded at 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 h post-exposure and compared with both negative and positive control groups. SEM was used to examine ultrastructural alterations, and statistical significance was set at p < 0.05.

Results:
Phytochemical analysis showed that the total phenol content was 10.34 % in the aqueous extract and 9.57 % in the ethanolic extract, while the total tannin content was 8.38 % and 8.06 %. In the in vitro assay, the aqueous extract at 10 % induced 100 % mortality within 10 h. SEM examination revealed marked ultrastructural alterations, including surface aggregates and pronounced wrinkling in the buccal region, along the body surface, and around the genital area, suggesting substantial disruption of cuticular integrity following treatment, with these changes resembling those observed in worms treated with albendazole.

Conclusion:
Overall, these findings provide in vitro evidence that the aqueous extract has anthelmintic potential. A 10% aqueous extract achieved complete worm death within 10 hours, and SEM observations indicated that this effect may be related to disruption of cuticular integrity. However, in vivo confirmation and toxicity assessment are needed before field application.

Key words: Haemonchus contortus; SEM; Cocos nucifera L. var. rubescens; Husk; Anthelmintic.