<i>Cleome monophylla</i> essential oil and its constituents as tick (<i>Rhipicephalus appendiculatus</i>) and maize weevil (<i>Sitophilus zeamais</i>) repellents

Abstract

Abstract The repellency of the essential oil of the shrub Cleome monophylla (Family: Capparidaceae) and identified constituents of the oil were evaluated against the livestock tick, Rhipicephalus appendiculatus and the maize weevil, Sitophillus zeamais. In a tick climbing repellency bioassay, the oil of C. monophylla exhibited repellency which, at the highest dose, was comparable to that of the commercial arthropod repellent N, N‐diethyl toluamide (DEET). In a Y‐tube olfactometer bioassay, C. monophylla oil showed higher or comparable repellency against S. zeamais relative to DEET at all the doses tested. 14 Compounds were identified in the C. monophylla oil by GC, GC‐MS and coinjection with authentic samples. Terpenolene was found to occur in largest quantity (14%) followed by 1‐α‐terpeneol (10%), pentacosane (9%), (α + β)‐humulene (8%), phytol (5%) and 2‐dodecanone (4%). The most repellent components against R. appendiculatus and S. zeamais were 1‐α‐terpeneol and 2‐dodecanone. The overall pattern of repellency activity of the C. monophylla constituents with respect to the two arthropods was, however, different. The potential of C. monophylla in tick and maize weevil control is discussed.