Respostas eletrofisiológicas das Porossensilas das quelíceras de Rhipicephalus microplus frente à fagoestimulantes e soros de bovinos

• Autor(a) principal: Ferreira, Lorena Lopes
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/0013000009qx2
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/4277
• topic: Fagoestimulantes; Rhipicephalus microplus; Sistema gustativo; Soro bovino; spikes; Bovine serum; Phagostimulants; Taste system; PATOLOGIA ANIMAL::ANATOMIA PATOLOGIA ANIMAL

Ticks are external parasites distributed in the world. Its parasitism causes direct and indirect damage to their hosts. Rhipicephalus microplus is the principal ectoparasite of the livestock causing economic and sanitary implications in the tropics regions. Control strategies are still a challenge and new alternatives are being sought to avoid the use of chemical methods that are reprehensible in relation to animal and human health, and also the environment. It is known that Bos indicus are more resistant to ticks than Bos taurus, while their crosses have a moderate resistance. The olfactory and gustatory senses allow these parasites to seek hosts, mating partners and distinguish between food and harmful substances. The receptors of these sensory organs are present throughout the body and appendages of arthropods, being pore sensilla in the chelicerae important when it comes to ticks taste receptors. Electrophysiology assists in the discovery of active principles that attract or repel these parasites and this will be proven after a behavioral test. This work was performed in order to characterize R. microplus electrophysiological responses to phagostimulants in different concentrations like salts (NaCl and KCl, 10-3 a 10-1M), glucose (10-4 a 10-1M), adenosine triphosphate (ATP, 10-6 a 10-2M), reduced glutathione (GSH, 10-6 a 10-2M), a mixture of substances (MIX, glucose1M+ATP10- 2M+GSH10-3M) and sera of susceptible and resistant cattle to ticks. A single cell electrophysiology technique was used in the taste sensila of R. microplus. Engorged nymphs of R. microplus were collected from naturally infested bovines. Females ticks were fed on rabbits for a period of three to five days. The females were removed and taken directly to the electrophysiology room in order to be prepared for the test. At least 10 females were tested per substance. The shape, frequency and amplitude of spikes were analyzed with the program Autospike. The statistical analysis was performed with the software R applying ANOVA followed by Tukey HSD post-hoc (5%). In relation to the phagostimulants it was observed that the taste receptors of the chelicerae were responsive for all substances tested, having a more intense responses at higher concentrations. The frequency of responses to salts ranged from 11.09 ± 0.98 to 28.50 ± 3.49 spikes/s; to glucose from 25.40 ± 2.33 to 37.15 ± 4.47 spikes/s, to ATP from 17.91 ± 1.28 to 37.30 ± 4.77 spikes/s; to GSH from 19.10 ± 2.84 to 56.6 ± 5.08 spikes/s and the MIX 50.60 ± 4.42 spikes/s. The responses were uni or multicellular depending on the concentration. Sera from resistant cattle xiii triggered a higher frequency of spikes/s (average of 53.48 ± 1.89 spikes/s, ranging from 48.45 ± 4.28 to 61.05 ± 5.14 spikes/s) when compared with the susceptible cattle (average of 40.33 ± 1.63 spikes/s, ranging from 33.30 ± 3.02 to 49.05 ± 5.20 spikes/s). The records analyzed showed that R. microplus was more stimulated by sera from resistant cattle than those from susceptible animals. It is known that in the serum has phagostimulants which probably triggered spikes in both groups. On the other hand, the greater number of spikes to resistant bovine serum might be due to the presence of deterrents compounds. Both sera showed a multicellular response. It was also observed that there were variations in the spikes frequency between animals of the same group according to the characteristic of spikes recorded. It was concluded that R. microplus respond in a dose dependent pattern to the phagostimulants tested. And also that, this tick was able differentiated the sera of susceptible to sera of resistant bovines.