Identification of a non-host semiochemical from miniature pinscher, Canis lupus familiaris, that repels Rhipicephalus sanguineus sensu lato (Acari: Ixodidae).

It is already known that the beagle breed of domestic dogs produces semiochemicals capable of repelling the brown dog tick, Rhipicephalus sanguineus sensu lato (s.l.). With a view to discovering new non-host semiochemicals as tick repellents, we compared the semiochemicals produced by a putative tick-resistant breed of dog, miniature pinscher, with known tick-resistant (beagle) and tick-susceptible (English cocker spaniel) breeds. Two non-host compounds produced by beagles, i.e. 2-hexanone and benzaldehyde, were shown to be present in samples collected from all three breeds. Furthermore, two compounds, 6-methyl-5-hepten-2-one and 1,2,4-trimethylbenzene, were found in higher amounts in samples collected from miniature pinscher dogs. The mean amounts of benzaldehyde, 2-hexanone and 1,2,4-trimethylbenzene were similar for beagles and miniature pinschers (P > 0.05) and higher than the means observed for cocker spaniels (P < 0.05), whereas the mean amount of 6-methyl-5-hepten-2-one produced by miniature pinschers was significantly higher (P < 0.05) than for the other breeds of dogs. In Petri-dish assays with adult R. sanguineus s.l., 6-methyl-5-hepten-2-one was repellent for all observation periods evaluated for the two highest concentrations (0.100 and 0.200 mg.cm-2, P < 0.01). The obtained results support our hypothesis that miniature pinschers are a tick-resistant dog breed and agree with previous observations of miniature pinschers being the breed least parasitized by ticks. Furthermore, the non-host semiochemical 6-methyl-5-hepten-2-one has potential to be developed for use as a repellent for the protection of susceptible dogs from R. sanguineus s.l. ticks.

Efficacy of collars with allomones on dogs to control Rhipicephalus sanguineus sensu lato infestations under field conditions.

Benzaldehyde and 2-hexanone are allomones produced by beagle dogs that reduce infestation by Rhipicephalus sanguineus sensu lato on these animals and on susceptible dogs which artificially release these repellents. These observations were obtained in previous laboratory tests or artificial infestations of susceptible dogs under controlled conditions. Here we evaluated the efficacy of collars delivering these repellents for suppressing the loads of R. sanguineus s.l. on naturally infested mixed-breed dogs under field conditions. Thirty dogs naturally infested with R. sanguineus s.l. were separated into two groups with 15 dogs each. The dogs from the treatment group received the collars with slow-release formulations of the allomones, and the dogs from the control group received collars without such compounds. Collar effectiveness tests were carried out over 30 days. All ticks found were removed from each dog, identified, and counted every collection day. The density of the different life stages of R. sanguineus s.l. varied greatly between groups and across evaluation times. Adult ticks were the stage most abundant and prevalent on infested dogs. The counts for larvae, nymphs and adults were similar between the control and the treatment groups within each tick collection day. Conversely, when we considered the total number of ticks over 30 days and gathered all life stages collected in the same animal, the dogs from the control group had significantly higher loads (35.3 ± 4.27) of ticks than the dogs from the treatment group (21.8 ± 2.96) (P < 0.01). In addition, the efficacy of treatment with repellent collars was high for adult ticks (30.8%) but was extremely low for reducing larval or nymphal infestation (0 or 2.6%, respectively). The present study demonstrates, for the first time, the efficacy of these volatile compounds on naturally infested dogs under field conditions. The development of a technologically enhanced device for slow release of the allomones tested here can be an advantageous alternative for reducing R. sanguineus s.l. infestation on dogs in residential environments.

Fauna helmintológica de catetos (Tayassu tajacu Linnaeus, 1758) procedentes da Amazônia Brasileira / Helminthic parasites of the collared peccaries (Tayassu tajacu Linnaeus, 1758) of the Brazilian Amazon

Tayassu tajacu, popularmente conhecido como cateto, é uma espécie silvestre encontrada em quase todo o continente Americano, sendo abundante em seus locais de ocorrência. O trabalho objetivou conhecer a fauna helmintológica, bem como os indicadores de infecções, de catetos (T. tajacu) procedentes da Amazônia Brasileira. Para tanto, foram utilizados cinco animais adultos (três machos e duas fêmeas), capturados no município de Araguaína, estado do Tocantins, com auxílio de armadilhas. Os catetos foram tranquilizados, contidos quimicamente e eutanasiados segundo o Guia Brasileiro de Boas Práticas para Eutanásia em Animais do Conselho Federal de Medicina Veterinária. As espécies encontradas foram identificadas e os indicadores de infecção foram determinados (percentual de infecção, abundância, intensidade média e variação da intensidade). Foi coletado um total de 1394 helmintos, sendo nove espécies de nematódeos: Eucyathostomum dentatum, Cruzia brasiliensis, Monodontus semicircularis, Monodontus aguiari, Spiculopteragia tayassui, Texicospirura turki, Parabronema pecariae, Physocephalus sexalatus, Cooperia punctata. Os helmintos com maiores percentuais de infecção foram Physocephalus sexalatus, Parabronema pecariae e Monodontus aguiari, encontrados em 100% dos animais examinados, sendo este último o mais abundante (164), com maior intensidade média (164) e com maior número total de helmintos (820). Em contrapartida, Spiculopteragia tayassui foi a espécie que obteve menores indicadores, sendo encontrada apenas uma fêmea neste estudo. Foi relatada, neste trabalho, a primeira ocorrência de Cruzia brasiliensis parasitando catetos (T. tajacu) no Brasil, espécie até então descrita e encontrada apenas parasitando suínos domésticos.(AU)

Tayassu tajacu, popularly known as collared peccary, is a wildlife species found throughout the American continent, being abundant in their places of occurrence. This study aimed to describe the helminthological fauna, as well as the infection indicators, of the collared peccary (T. tajacu) coming from the Brazilian Amazon. Five adult peccaries (three males and two females) were captured in the Araguaína region, Tocantins, Brazil, with the aid of traps. The collared peccaries were reassured, chemically restrained and euthanized according to the Brazilian Good Practice Guide for Animal Euthanasy of the Federal Board of Veterinary Medicine. The species found were identified and the infection indicators were determined (infection rate, abundance, mean intensity and intensity variation). A total of 1394 helminths of nine nematode species were collected: Eucyathostomum dentatum, Cruzia brasiliensis, Monodontus semicircularis, Monodontus aguiari, Spiculopteragia tayassui, Texicospirura turki, Parabronema pecariae, Physocephalus sexalatus and Cooperia punctata. Helminths with higher percentages of infection were Physocephalus sexalatus, Parabronema pecariae and Monodontus aguiari found in 100% of the examined animals; the latter was the most abundant (164) and had a highest mean intensity (164) and total number of helminths (820). In contrast, Spiculopteragia tayassui presented lower indicators, found only one female in this study. In this studythe the first occurrence of Cruzia brasiliensis parasitizing collared peccary (T. Tajacu) in Brazil was reported, specie hitherto described and only found parasitizing domestic pigs.(AU)