Identification of a non-host semiochemical from tick-resistant donkeys (Equus asinus) against Amblyomma sculptum ticks

A - Papers appearing in refereed journals

Ferreira, L. L., Sarria, A. L. F., De Olivera Filho, J. G., De Olivera de Silva, F., Powers, S. J., Caulfield, J. C., Pickett, J. A., Birkett, M. A. and Borges, L. M. F. 2019. Identification of a non-host semiochemical from tick-resistant donkeys (Equus asinus) against Amblyomma sculptum ticks. Ticks and Tick-Borne Diseases. 10 (3), pp. 621-627.

AuthorsFerreira, L. L., Sarria, A. L. F., De Olivera Filho, J. G., De Olivera de Silva, F., Powers, S. J., Caulfield, J. C., Pickett, J. A., Birkett, M. A. and Borges, L. M. F.
Abstract

Amblyomma sculptum is a tick affecting animal and human health across Argentina, Bolivia, Paraguay and Brazil. Donkeys, Equus asinus, are known to be resistant to A. sculptum, suggesting that they can produce non-host tick semiochemicals (allomones), as already demonstrated for some other vertebrate host/pest interactions, whereas horses, Equus caballus, are considered as susceptible hosts. In this study, we tested the hypothesis that donkeys produce natural repellents against A. sculptum, by collecting sebum from donkeys and horses, collecting the odour from sebum extracts, and identifying donkey-specific volatile compounds by gas chromatography (GC) and coupled GC-mass spectrometry (GC–MS). From the complex collected blends, five main compounds were identified in both species. Hexanal, heptanal and (E)-2-decenal were found predominantly in donkey extracts, whilst ethyl octanoate and ethyl decanoate were found predominantly in horse extracts. One compound, (E)-2-octenal, was detected exclusively in donkey extracts. In Y-tube olfactometer bioassays 36 different A. sculptum nymphs were tested for each extract, compound and concentration. The dry sebum extracts and the compounds identified in both species induced neither attraction nor repellency. Only (E)-2-octenal, the donkey-specific compound, displayed repellency, with more nymphs preferring the arm containing the solvent control when the compound was presented in the test arm across four concentrations tested (p < 0.05, Chi-square test). A combination of a tick attractant (ammonia) and (E)-2-octenal at 0.25M also resulted in preference for the control arm (p < 0.05, Chi-square test). The use of semiochemicals (allomones) identified from less-preferred hosts in tick management has been successful for repelling brown dog ticks, Rhipicephalus sanguineus sensu lato from dog hosts. These results indicate that (E)-2-octenal could be used similarly to interfere in tick host location and be developed for use in reducing A. sculptum numbers on animal and human hosts.

KeywordsAmblyomma cajennense sensu lato ; Donkey; Non-host; (E)-2-octenal; Repellent; Allomone
Year of Publication2019
JournalTicks and Tick-Borne Diseases
Journal citation10 (3), pp. 621-627
Digital Object Identifier (DOI)doi:10.1016/j.ttbdis.2019.02.006
PubMed ID 30799282
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeBilateral BBSRC-FAPESP: Defining the Genetic and Semiochemical Basis of Tick Resistance in Cattle
Publisher's version
Output statusPublished
Publication dates
Online16 Feb 2019
Publication process dates
Accepted10 Feb 2019
PublisherElsevier Gmbh, Urban & Fischer Verlag
Copyright licenseCC BY
ISSN1877-959X

Permalink - https://repository.rothamsted.ac.uk/item/8w96v/identification-of-a-non-host-semiochemical-from-tick-resistant-donkeys-equus-asinus-against-amblyomma-sculptum-ticks

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