Big tick for research: Donkeys may provide new repellent

By | April 21, 2019
 donkeys are resistant to the Amblyomma sculptum tick Big tick for research: Donkeys may render novel repellent
Unlike horses, donkeys are resistant to the Amblyomma sculptum tick.

A possible novel tick repellent has been isolated from ass sebum (the oily pith secreted yesteryear sebaceous glands to occur pare moisturised.)

Amblyomma sculptum, a species of tick constitute inwards South America, feeds on animals too humans. It is an of import vector of Rickettsia rickettsii, the agent responsible for Brazilian Spotted Fever (Rocky Mountain Spotted Fever inwards USA) – the nearly lethal tick-borne pathogen affecting humans.

The Equus caballus is a mutual host for the tick, too although horses may convey antibodies to R rickettsii, clinical signs of affliction are rare.

Unlike horses, donkeys are resistant to the tick. Researchers at the Federal University of Goiás, Brazil, working amongst colleagues at the Rothamsted Research inwards the United Kingdom have been investigating whether this could live on due to differences inwards the secretions of the sebaceous glands inwards the pare of horses too donkeys.

The researchers collected sebum from donkeys too horses too isolated the volatile compounds it contained. They constitute 5 compounds, acquaint inwards differing proportions inwards horses too donkeys. However, 1 compound, ((E)-2-octenal), was constitute exclusively inwards ass extracts too non inwards Equus caballus extracts.

Further tests were carried out amongst this chemical compound using a Y-tube olfactometer, a technique ordinarily used inwards chemic ecology research. Amblyomma sculptum nymphs were given the choice betwixt ii odor sources to examination behavioural preferences.

The query squad constitute that the dry out sebum extracts too the 5 compounds identified inwards both horses too donkeys had neither attractant nor repellent effects.

Only (E)-2-octenal, the chemical compound constitute exclusively inwards ass sebum, showed a repellent effect. More nymphs preferred the arm containing the solvent command than the examination arm. The researchers reported than “even a combination of ammonia (which attracts ticks) too (E)-2-octenal at 0.25 M likewise resulted inwards preference for the command arm.”

The authors propose that (E)-2-octenal could live on used equally a repellent to interfere amongst ticks locating their host too to help trim down Amblyomma sculptum numbers on creature too human hosts.

Source: Equine Science Update

Identification of a non-host semiochemical from tick-resistant donkeys (Equus asinus) against Amblyomma sculptum ticks.
Ferreira LL, Sarria ALF, de Oliveira Filho JG, de Silva FO, Powers SJ, Caulfield JC, Pickett JA, Birkett MA, Borges LMF.
Ticks too Tick-Borne Diseases. 2019 February 16. pii: S1877-959X(18)30414-X.


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