Acaricidal activity of Margaritaria discoidea (Euphorbiaceae) plant extracts against the ticks Rhipicephalus appendiculatus and Amblyomma variegatum (Ixodidae)

Abstract

A water soluble extract of M. discoidea, an African indigenous plant induced high mortalities in nymphs of both Rhipicephalus appendiculatus, and Amblyomma variegatum and in adult R. appendiculatus, but not in adult A. variegatum. An oil hexane extract from dry wood of this plant was found to be more acaricidal and a 6.25% concentrated extract killed 100% nymphal R. appendiculatus, 100% adult R. appendiculatus and 100% adult A. variegatum when exposed to the extract for 10 min. Application of a 50% concentrated oil extract on rabbit ears caused a complete inhibition of attachment by adult R. appendiculatus and A. variegatum for at least 4 days, and when applied on adult ticks engorging on rabbits, it induced mortalities of 70% and 97% in A. variegatum and R. appendiculatus, respectively. When applied on ticks naturally infesting cattle in the field, the 50% oil extract induced 100% and 50% mortalities in adult R. appendiculatus and A. variegatum, respectively, by 2 days post-application. In adult R. appendiculatus, feeding on cattle the 50% oil extract was found to be as effective as the standard concentration (0.05%) of steladone, a commercial acaricide.