Abstract / Summary
Ticks are major vectors of pathogens, imposing significant health and economic burdens on humans and animals. Conventional synthetic acaricides face increasing limitations due to resistance and environmental concerns, highlighting the need for eco-friendly alternatives. We developed a topical cream based on ethanolic extracts of Tagetes erecta flowers and evaluated its repellency against larval and adult Haemaphysalis bispinosa under controlled laboratory conditions. Repellency was assessed using three independent biological replicates ( n = 3), with 200 larvae or 20 adults per replicate, over a 6-h observation period. Two-way ANOVA followed by Tukey’s multiple-comparison test showed significant effects of treatment and observation time on repellency ( P < 0.05). The selected cream demonstrated high repellency, reaching 97.5 ± 2.5% in larvae and 87.5 ± 2.4% in adults at selected time points. The extract-based formulation also exhibited concentration-dependent inhibition of acetylcholinesterase (AChE), reaching 61.56 ± 2.50% inhibition at 1000 µg/mL, with an estimated IC₅₀ of 267.6 µg/mL. Molecular docking identified several phytoconstituents with favorable predicted interactions with the modelled tick AChE (RmAChE1), including Nonylamine N, N-di(allyl) (–9.29 kcal/mol), 1 H,3 H-furo[3,4-c]furan (–7.09 kcal/mol), and Yangambin (–6.53 kcal/mol). Yangambin also showed a predicted interaction with the tick salivary protein BSAP1 (–4.055 kcal/mol), and molecular dynamics simulations indicated persistence of the predicted BSAP1–Yangambin complex over 100 ns. Because the BSAP1 findings were based solely on computational analyses, they represent a potential protein–ligand interaction rather than demonstrated functional inhibition. Overall, the findings demonstrate promising laboratory anti-tick activity of the T. erecta -based formulation, together with measurable in vitro AChE inhibitory activity and computationally predicted interactions with selected tick proteins.