Pheromone-mediation of host-selection in bont ticks (Amblyomma hebraeum Koch)

The bont tick, Amblyomma hebraeum, is the principal vector to southern African ruminants of heartwater (Cowdria ruminantium infection). The role of feeding male ticks, which emit an aggregation-attachment pheromone, in attracting unfed ticks to cattle was investigated. Calves infested with feeding male ticks were more attractive to unfed adult ticks than were uninfested calves. The presence of the pheromone on previously infested cattle apparently allows unfed ticks to discriminate between hosts on which these parasites have fed successfully (suitable hosts) and those on which they have not (potentially unsuitable hosts). The use of acaricides is thus unlikely to reduce bont tick populations in areas where adequate numbers of alternate (wild) hosts are present. Also, cattle so treated may lose their resistance to heartwater through lessened exposure to infected ticks

Heartwater : past, present and future : proceedings of a workshop held at Berg en Dal, Kruger National Park, on 8-16 September 1986

Mallory's phloxine-methylene blue stain was used to differentiate colonies of Cowdria ruminantium in midgut epithelial cells of nymphal Amblyomma hebraeum that had been infected as larvae. Gut tissues were collected from nymphs that had fed on a susceptible sheep and were fixed in formol-saline on the day of repletion. Paraffin sections, 3-4 μm thick, were then stained and this rendered colonies and cell nuclei densely blue against a uniformly pink background of tick tissues. Colonies were easily distinguished from nuclei by their specific morphology. This method of parasite visualization may be adapted to field-collected ticks for rapid detection of C. ruminantium or to assays of susceptibility of tick populations to various strains of the organism.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Spiroplasma ixodetis sp. nov., a new species from Ixodes pacificus ticks collected in Oregon

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