Repellence of cattle anal odor constituents and selected analogues against Rhipicephalus appendiculatus.

Abstract

A study was conducted to determine repellence of anal odour constituents, blends and selected analogues against Rhipicephalus appendiculatus control. The odours were trapped, eluted and analyzed by gas chromatography-linked mass spectrometry. Constituents were identified by comparing their mass spectra with those in the National Institute of Standards and Technology libraries. Major constituents were o-xylene, 4-hydroxy-4-methyl-2-pentanone, 4-methyl-2-methoxyphenol, ethyl benzene, 2,6,6-trimethyl-[1S(1α,β,5α)]bicycloheptanes, 5-ethoxydihydro-2(3H)-furanone, 3-methylene-2-pentanone, 5-methyl-2-phenyl-1H-indole, and 3-pentanone. Repellency of the odours, selected constituents and blends was evaluated using dual choice tick climbing assay. The 4-methyl-2-methoxyphenol was most repellent (RD75 =0.56) and 3-pentanone least active (RD75 = 622.7). Two blends that were more repellent than the anal odour were: made up of 4-methyl-2-methoxyphenol, 3-pentanone, 3-methyl-2-pentanone, and 4-hydroxy-4-methyl-2-pentanone, with RD75 of 0.032, and another without 3-pentanone, with RD75= 0.019; p≤0.05, SNK. Bioassays of analogues of 4-methyl-2-methoxyphenol (4-Methylguaiacol) was done: guaiacol, eugenol, 3,4-methylenedioxytoluene and 2,4-dimethylphenol, where 3,4-Methylenedioxytoluene was inactive, while 2,4-dimethylphenol was most repellent (RD75= 0.0089) compared to all compounds and blends tested. The 2,4-dimethylphenol analogue of 4-methylguaiacol may represent a promising additional tool in the arsenal of techniques in East Coast Fever control.