In vitro acaricidal activity of extracts of red cultivar Allium cepa L. on engorged female Rhipicephalus (Boophilus) annulatus from naturally infested cattle

Abstract

Introduction: Tick infestation is a major challenge facing livestock production in the Sub-Saharan zone. Most species of ticks have developed resistance to most of the available synthetic acaricides. Hence, the need to search for and develop ethno-acaricidal products. This study investigated the in-vitro acaricidal activity of aqueous and methanol extracts of red cultivar Allium cepa L. on engorged female Rhipicephalus (Bophillus) annulatus ticks. Methods: The extracts were prepared using standard method and the final brownish black extracts were kept in the refrigerator at 4oC. In-vitro acaricidal bioassay was done using the adult immersion test. Engorged ticks were randomly assigned into six groups (I-VI) (50mg/ml, 100mg/ml, 200mg/ml, and 400mg/ml (of the extracts), Distilled water (10 ml/kg) and Cypermethrin (10% EC) having three (3) replicates per group and containing 10 ticks per replicate administered. Results: Tick mortality of 66.66 % was effected by immersion in 400 mg/ml aqueous extract of red cultivar A. cepa as against 60 % obtained with cypermethrin within the same period. Aqueous extract caused 80 % inhibition of oviposition 72 hours post immersion (PI) as against 40 % caused by appli-cation of cypermethrin. Significance: The tickicidal and anti-oviposition activities of crude aqueous and methanol extract of red cultivar A. cepa L. observed in this present study revealed that the extracts possess some acaricidal properties/principles. Therefore, the plant could be an alternative source of tick control method with similar benefits compare to chemical acaricides such as cypermethrin, but without exposing our environment, animal and human to hazard.