Estudos biológicos e moleculares de Amblyomma parvum Aragão, 1908 (Acari: Ixodidae) da Argentina e Brasil

Abstract

It is extremely important the knowledge about ecological characteristics in different biomes and how each population behaves to adversities of the environment they live in. It has been observed that some tick species widely distributed may have genetic and / or biological differences between populations. The tick Amblyomma parvum has a wide distribution Neotropical with an extensive list of hosts. To try to elucidate these gaps on the subject, studies were developed in Laboratório de Ixodologia and Biologia Molecular in Departamento de Parasitologia Animal in Universidade Federal Rural do Rio de Janeiro. When comparing the life cycle of this parasite from three colonies of different locations (Pantanal Sul-matogrossense, Cerrado, Goias and Chaco, Argentina) it was observed that the complete cycle of A. parvum was completed in an average period of 104.2; 99.6 and 100.7 days for the Pantanal, Chaco and Cerrado respectively. We conclude that the biological parameters of the three populations are quite similar. It is also not fully understood as terrestrial arthropods survive the temporary flooding following heavy rains then the purpose of the second chapter was to compare the effect of immersion in the life cycle in order to respond to water stress can affect and/or changes in the reproductive efficiency. It can be observed that the Pantanal population was more sensitive to immersion even though the observation ecdysis in group 96 hours. Despite this in group 48 of the Pantanal population there was no continuation of the cycle while the Chaco and Cerrado populations continued its cycle even after the nymphs remain submerged 48 hours. It can be observed that from 72 hours immersion causes a deleterious effect on this species. The results reported here suggest that the ability to survive underwater for a period is a additional aspect of the biology of this species of tick. With respect to the molecular analysis was demonstrated in literature genetic divergence (3.0 to 3.7%) of A. parvum Argentinean and Brazilian. However, analysis of a single gene is not robust enough to make inferences about the significance of the genetic differences between different populations, so new sequences of molecular markers obtained from A. parvum belonging to different locations in Argentina and Brazil have been evaluated. Results for the genes 12S and COI there was a significant difference point of to consider them as distinct species in South America, 3.8% and 7.1% respectively. But when we observe the results for the ITS2 gene there was not enough difference to characterize different species. View of these biological and molecular results are recommended further analysis with new samples of new locations in order to elucidate this question about the possibility of this kind in South America be different species.