Submitted to: Advances in Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2021
Publication Date: 4/28/2021
Citation: Tsikolia, M., Opatz, T., Kauhl, U., Tabanca, N., Demirci, B., Tenbroeck, S., Linthicum, K., Bernier, U.R. 2021. Trials for gathering information on an unknown peak in the GC-MS spectra of horse and pony hair extracts. Advances in Entomology. 9(2):100-111. https://doi.org/10.4236/ae.2021.92009.
DOI: https://doi.org/10.4236/ae.2021.92009

Interpretive Summary: Blood-feeding flies such as stable flies, horse flies, and deer flies can cause irritation and distress in mammals. Tabanid flies impact mammals via transmission of disease, reduced weight gains in animals and annoyance. Secretions from the skin surface of mammals contain an array of compounds and some of these compounds are likely attractive to biting flies. To identify components responsible for the attraction of flies and other insects to horses, we investigated horsehair volatiles/extracts. Gas chromatography–mass spectroscopy (GC-MS) analysis led to the discovery of an unknown compound. It was the most abundant peak in the chromatogram. This compound was not detected in similar analyses of dog and donkey hair extracts; however, it was observed in the hair extract from a pony. This report details our attempt to identify the unknown compound in horse and pony hair.

Technical Abstract: The volatile compounds from horse and pony hairs and skin were analyzed to determine bioactive molecules that are kairomones used for host location by blood-feeding diptera. In this study, horse and pony hair samples were extracted with organic solvents (pentane or hexane) and analyzed by gas chromatography-mass spectrometry analysis (GC-MS) with closed electron ionization (CEI). Using the GC-MS analysis, we observed a compound peak, which could not be identified by comparison to mass spectra in the mass spectral library. This unknown compound was often the largest peak in the chromato-gram and had a retention index and mass spectral fragmentation similar to nonanal. However, there were several differences in the fragmentation pattern. When compared to a nonanal reference standard, it was evident that this was a different compound. Hydrodistillation of pony hair was another extraction method to obtain the unknown component in higher concentrations. Analysis of this extract with GC-flame ionization detector (FID) with GC-MS confirmed the same unknown peak. Further experiments and analysis with the various mass spectroscopy tools gave the possible molecular ion with mass-to-charge ratio (m/z) 142, corresponding to the unknown component.