Effect of Tagetes minuta essential oil on the central nervous system of unfed Rhipicephalus sanguineus sensu lato 'tropical lineage' ticks.

Rhipicephalus sanguineus sensu lato 'tropical lineage' (Acari: Ixodidae) is considered a sanitary concern due to its role as a disease vector. Tick strains resistant to synthetic acaricides have caused difficulties in their control, besides synthetic acaricides are harmful to the environment and to the health of non-target animals. The research of plants with acaricidal and repellent properties has proved to be an efficient alternative in tick control. The genus Tagetes spp. excels for its use as traditional pest control in households and plantations and also for its potential as an acaricide against R. sanguineus under laboratory conditions. The first aim of the present study was to evaluate the effect of different doses of Tagetes minuta essential oil (TMEO) on the central nervous system (synganglion) in unfed R. sanguineus adults. The histological analysis of synganglion exposed to the different concentrations of TMEO and amitraz 12.5% (50% of the recommended dose in the package insert) showed a significant effect with signs of cell damage including volume increase, loss of shape, and vacuolization, in addition to chromatin alterations such as condensation, margination, and fragmentation. TMEO were analyzed by gas chromatography coupled with mass spectrometry showing the presence of 21 compounds that according to their chemical structure are classified as terpenoids. Among them (Z)-ß-ocimene, ocimene, (Z)-tagetone, and verbenone were found in major quantities.

Establishment and multiapproach characterization of Amblyomma sculptum (Acari: Ixodidae) cell line (ASE-14) from Brazil.

The establishment and characterization of the ASE-14 cell line derived from embryos of Amblyomma sculptum is described here. Primary cultures were started, and after 60 days of culturing a confluent monolayer was formed and the first subculture was then carried out. After this, new subcultures were carried out every 4 weeks. Cryopreservation of cells was successful only after the 14th subculture. We compared the chromosomes of the ASE-14 cell line with those of parental ticks. Cytogenetic analysis revealed occurrences of variable and increased diploid numbers in the ASE-14 cell line in comparison with adult ticks, probably through polyploidization events, chromosome fusions and translocations, which allowed generation of cells with distinct diploid numbers. Confirmation of the origin of the A. sculptum cell line was obtained through conventional PCR and sequencing of a fragment of the mitochondrial 16S rRNA gene. In addition, no DNA from Anaplasma marginale, Anaplasma spp., Babesia/Theileria spp., Bartonella spp., Coxiella spp., Ehrlichia canis, Mycoplasma spp. or Rickettsia spp. was detected in the cells through PCR assays. Cytological analyses were performed using live phase contrast microscopy and cytocentrifuge smears stained with Giemsa, while periodic acid-Schiff and bromophenol blue staining techniques were used to detect polysaccharides and protein, respectively. In conclusion, a new cell line derived from embryos of A. sculptum was generated and characterized in this study. The ASE-14 cell line was deposited in the Tick Cell Biobank at the University of Liverpool, and in the Tick Cell Biobank South America Outpost at the Oswaldo Cruz Foundation (FIOCRUZ). The ASE-14 cell line is an important addition to the existing panel of tick cell lines and can be used as a tool for advancing research in various areas of the virology, bacteriology, biology and control of this tick.