Respostas eletrofisiológicas das Porossensilas das quelíceras de Rhipicephalus microplus frente à fagoestimulantes e soros de bovinos
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2013-09-20
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Universidade Federal de Goiás
Resumo
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
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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.
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FERREIRA, Lorena Lopes. Respostas eletrofisiológicas das Porossensilas das quelíceras de Rhipicephalus microplus frente à fagoestimulantes e soros de bovinos. 2013. 61 f. Dissertação (Mestrado em Ciência Animal)–Universidade Federal de Goiás, Goiânia, 2013.