title: Identification of non-host semiochemicals for the brown dog tick, Rhipicephalus sanguineus sensu lato (Acari: Ixodidae), from tick-resistant beagles, Canis lupus familiaris.
abstract: Studies have shown that the brown dog tick, Rhipicephalus sanguineus sensu lato, when fed on the beagle breed of dog, Canis lupus familiaris, development negatively affected in comparison with tick development after feeding on the English cocker spaniel breed. Thus leading to the suggestion that beagle dogs are be tick-resistant dogs. Behavioural studies have demonstrated that more ticks are attracted by extracts from cocker spaniels than from beagles and that the odour of beagles is a repellent. To test the hypothesis that resistant hosts produce repellent compounds, we undertook comparative chemical analysis on beagle odour and cocker spaniel extracts using coupled high-resolution gas chromatography-mass spectrometry (GC-MS) and also used Petri-dish and olfactometer behavioural assays to assess the response of ticks to identified non-host compounds. The beagle odour extracts contained almost three times as many chemical compounds as cocker spaniel samples. Several non-host compounds were identified, i.e. 2-hexanone, benzaldehyde, nonane, decane and undecane. In Petri-dish assays, 2-hexanone was repellent at 30 min at concentrations of 0.200 and 0.050 mg cm(-2), whilst at 10 min, the 0.100 mg cm(-2) concentration was repellent. Benzaldehyde repelled ticks at 30 min (0.200 mg cm(-2)) and at 5 min (0.050 mg cm(-2)). Undecane was repellent for R. sanguineus s.l. ticks for the first 5 min at the highest concentration tested. Nonane and decane did not show any significant repellency at any concentration or time evaluated. When 2-hexanone and benzaldehyde were combined, an increase in the repellency rate was observed, with activity comparable or better than N,N-diethyl-3-methylbenzamide (DEET). In olfactometer bioassays, a 1:1 mixture of 2-hexanone:benzaldehyde and DEET were repellent for R. sanguineus s.l. adults at the concentration of 0.200 mg cm(-2). This study identified non-host semiochemicals that mediate avoidance of the beagle dog breed by R. sanguineus s.l. This finding may enable development of new approaches to control this tick.
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Rua 235 s/n, Setor Universitário CEP 74605050 Goiânia, Goiás, Brazil. Electronic address: borges.ligia@gmail.com.
authors.forename: Lígia Miranda Ferreira
authors.initials: LM
authors.lastname: Borges
authors.affiliation: Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Campus II, Samambaia, Cx. Postal 131, CEP 74001-970 Goiânia, Goiás, Brazil. Electronic address: jaires_filho@hotmail.com.
authors.forename: Jaires Gomes
authors.initials: JG
authors.lastname: de Oliveira Filho
authors.affiliation: Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Campus II, Samambaia, Cx. Postal 131, CEP 74001-970 Goiânia, Goiás, Brazil. Electronic address: loren4_lopes@hotmail.com.
authors.forename: Lorena Lopes
authors.initials: LL
authors.lastname: Ferreira
authors.affiliation: Instituto Federal Goiano, Campus Urutaí, Rodovia Geraldo Silva Nascimento Km 2,5, CEP 75790-000 Urutaí, Goiás, Brazil. Electronic address: carlalouly@gmail.com.
authors.forename: Carla Cristina Braz
authors.initials: CC
authors.lastname: Louly
authors.affiliation: Biological Chemistry and Crop Protection Department, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, United Kingdom. Electronic address: john.pickett@rothamsted.ac.uk.
authors.forename: John A
authors.initials: JA
authors.lastname: Pickett
authors.affiliation: Biological Chemistry and Crop Protection Department, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, United Kingdom. Electronic address: mike.birkett@rothamsted.ac.uk.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Birkett
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D004198:Disease Susceptibility / Q000662:veterinary*; D004283:Dog Diseases / Q000276:immunology / Q000469:parasitology*; D004285:Dogs; D005260:Female; D006790:Host-Parasite Interactions / Q000502:physiology; D010675:Pheromones / Q000737:chemistry* / Q000502:physiology*; D048508:Rhipicephalus sanguineus / Q000502:physiology*; D013984:Tick Infestations / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*
chemical_list: D010675:Pheromones
keywords: 2-Hexanone; Benzaldehyde; Dogs; Natural repellents; Rhipicephalus sanguineus sensu lato