RESUMO
The ecology of Amblyomma tonelliae (Ixodida: Ixodidae), including its seasonal distribution and the development periods of each stage, was investigated during a study carried out over two consecutive years in northwestern Argentina. In addition, the genetic variation of this tick was studied through analyses of 16S rDNA sequences. Amblyomma tonelliae has a 1-year lifecycle characterized by a long pre-moult period in larvae with no development of morphogenetic diapause. Larvae peak in abundance during late autumn and early winter; nymphs peak in abundance in spring, and adults do so from late spring to early summer. Amblyomma tonelliae shows a marked ecological preference for the driest areas of the Chaco ecoregion. In analyses of 16S rDNA sequences in genes from different populations of A. tonelliae, values for nucleotide diversity and the average number of nucleotide differences showed genetic diversity within this species to be low. No significant differences were found in comparisons among populations.
Assuntos
Ecossistema , Variação Genética , Ixodidae/fisiologia , Animais , Argentina , Feminino , Ixodidae/genética , Ixodidae/crescimento & desenvolvimento , Larva/genética , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Dados de Sequência Molecular , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Otobius megnini has an autogenous 1 host life cycle, where larvae and nymphs stay attached inside the ear canal for long periods, but the adult tick is free living and can lay several egg batches without feeding. In order to obtain information about anatomical structures involved in this particular life cycle, nymphs and adults of O. megnini were dissected and salivary gland images were obtained in situ with the use of scanning electronic microscopy. Measurements of salivary alveoli were obtained with the use of ImageJ 1.40 g software. In the nymphs, the Type I alveoli are relatively small (mean diameter: 19.6 µm) compared with those of the adults (mean: 43.4 µm) and other soft ticks in the literature. Type II alveoli in nymphs are similar (mean: 82.6 µm) to previously described alveoli in adult soft ticks. In contrast, the adults of O. megnini Type II alveoli are smaller (mean: 36.8 µm) and have a wrinkled surface. These findings provide more evidence that Type I alveoli take part in absorption of moisture during the free-living tick stages.