In vitro nematocidal activity of plant extracts of Mexican flora against Haemonchus contortus fourth larval stage.

Fourteen plant extracts were evaluated in vitro against the fourth larval stage of Haemonchus contortus. The plants species used were Tagetes erecta, Argemone mexicana, and Castela tortuosa. The assays were run in 24-well cell culture plates at room temperature with three replicates. After exposure, aliquots were taken from the corresponding wells and transferred to a microscope for observation. Evaluation criteria were based on the average of live and/or dead larvae. ANOVA test and Tukey test were used to determine significant differences among the treatments. After 96 h, the T. erecta acetonic extract produced 99.7% lethal activity, followed by C. tortuosa hexanic extract (85.8%) and T. erecta methanolic extract (58.3%) (P < 0.0001).