Location: Livestock Arthropod Pests ResearchTitle: Quantification of brown dog tick repellents, 2-hexanone and benzaldehyde, and release from tick-resistant beagles, Canis lupus familiaris
|GOMES OLIVEIRA FILHO, JARIES - Federal University Of Goias|
|SARRIA, ANDRE - Rothamsted Research|
|FERREIRA, LORENA - Federal University Of Goias|
|CAULFIELD, JOHN - Rothamsted Research|
|POWERS, STEPHEN - Rothamsted Research|
|PICKETT, JOHN - Rothamsted Research|
|Perez De Leon, Adalberto - Beto|
|BIRKETT, MICHAEL - Rothamsted Research|
|BORGES, LIGIA - Federal University Of Goias|
Submitted to: The Journal of Chromatography B: Biomedical Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2016
Publication Date: 6/1/2016
Citation: Gomes Oliveira Filho, J., Sarria, A.F., Ferreira, L., Caulfield, J.C., Powers, S.J., Pickett, J.A., Perez De Leon, A.A., Birkett, M.A., Borges, L. 2016. Quantification of brown dog tick repellents, 2-hexanone and benzaldehyde, and release from tick-resistant beagles, Canis lupus familiaris. The Journal of Chromatography B: Biomedical Applications. 1022:64-69.
Interpretive Summary: The brown dog tick, scientifically known as Rhipicephalus sanguineus, parasitizes animals and humans, and it is repelled by the volatile compounds 2-hexanone and benzaldehyde, which were discovered in the odor of Beagle dogs. A brown dog tick’s ability to locate a host depends among other things on the variation in odor components and ratios. The aim of this study was to develop an analytical method to quantify the release rate, and the ratio of 2-hexanone and benzaldehyde from Beagles. The odor of 3 Beagles was collected during a week on days 0, 1, 4, and 7. Analytical methods were applied in the laboratory to identify and quantify the volatile compounds. Both compounds were found in all dogs on all days. The amount of benzaldehyde detected tended to be around twice that of 2-hexanone. This knowledge supports the development of slow-release formulations to protect animals from infestation with the brown dog tick, which also transmits disease agents affecting humans.
Technical Abstract: We have recently shown that repellency of the tick Rhipicephalus sanguineus sensu lato by the tick resistant dog breed Beagle is mediated by volatile organic compounds 2-hexanone and benzaldehyde present in Beagle dog odour. Ectoparasite location on animal hosts is affected by variation in odour components and ratios. The aim of this study was to develop an analytical method to quantify the release rate, and the ratio, of 2-hexanone and benzaldehyde from Beagle dogs. The odour of three Beagles was collected, for four days, over one week (day 0, day 1, day 4 and day 7). The compounds were identified using coupled high-resolution gas chromatography–mass spectrometry (GC-MS), and authentic standards of compounds were used to generate external calibration curves for quantification. Both compounds were found in all dogs on all days. The amount of benzaldehyde was always higher than that of 2-hexanone and so their ratio varied from unity, on average (over time) being 3.128 ± 0.365, 1.902 ± 0.390, 1.670 ± 0.671 ng.mL-1 for beagle 1, 2 and 3, respectively. There was no significant (p < 0.05, F-test) effect of time. The overall average was 2.233 ± 0.387 ng.mL-1. Our results enhance our previous findings by documenting the presence of 2-hexanone and benzaldehyde in Beagle dog odour samples covering a 7-day period. This knowledge should support the development of slow-release formulations to protect dogs from R. sanguineus s. l. infestation.