Permethrin-impregnated fabric has been shown to be an effective repellent against various tick species. However, some tick species are not repelled by this chemical. In Hyalomma dromedarii (Koch), permethrin exposure is reported to actually enhance the tick's attachment behavior. This study evaluated the histological effects of permethrin exposure on the salivary glands and neuroendocrine organs of unfed, virgin H. dromedarii ticks of uniform age. Three fabric treatments consisting of unwashed-untreated (control), washed after treatment (0.125 mg [AI] / cm2) and unwashed-treated were used after 5- and 10-min exposure times for unfed, unmated females. For all of the organs examined, the cellular structure of treated ticks differed from controls as evidenced by increases in cellular activity, as well as significant increases in the size of the cells of the organs under study (P < 0.05). These data conclusively demonstrate that an unexpected enhanced attachment response observed in this tick species after permethrin exposure is the direct result of increased neurosecretory and salivary gland activity induced by that exposure.

Unfed and fed nymphal Argas hermanni Audouin were treated topically with 1, 5, 10, 15, and 20 micrograms of 25-azacholestane. The azasteroid did not inhibit feeding but had a dose-related lethal effect on unfed nymphs. Generally, it had little effect on nymphs treated after feeding. The 10-micrograms dose reduced the premolting period of nymphs treated before feeding. Some adults emerging from the 5- to 20-micrograms dosage groups that had been treated before feeding failed to shed their exuvia and others also had deformed legs. Greater numbers of adult females emerged from nymphs treated before feeding. The preoviposition period was almost the same in control females and of female mates, with males emerging from treated nymphs. Females from nymphs treated before feeding have a prolonged preoviposition period. Fecundity was reduced when males were treated with 10-20 micrograms as unfed nymphs. Egg hatch was reduced for females treated with 15 and 20 micrograms as fed nymphs, females treated with 5 and 10 micrograms as unfed nymphs, and as progeny of males treated with 10 micrograms as unfed nymphs. Results suggest possible interference with juvenile hormone titer in treated ticks.

The salivary glands in female H. dromedarii consists of three alveolar types, one agranular (type I) and two granular (type II and III). Five granule secreting cell types were identified according to their granular submicroscopic appearance. The structure and changes observed in type I alveoli before, during and after feeding suggest its role in ion and water transport from the haemolymph to the lumen during initial feeding. Secretory cells in salivary alveoli types II and III undergo substantial growth, differentiation and accumulation of secretory material during feeding and various rates of depletion directly after feeding. Attachment and limited feeding seems to provide a stimulus for synthesis of proteins, lipids and carbohydrates, whereas detachment from the host decreases the secretory competence of these alveoli causing its degeneration.

: Thirteen Neurosecretary Cell (NSC) types have been observed in the unfed female Hyalomma dromedarii synganglion. Distribution of these types was based on cell shape, size, and staining reaction of their contents. The NSC are grouped in 13 centers, namely protocerbral, cheliceral, stomodeal pons, palpal, oesophageal, globular, olfactory, glomerular, four pedal, opisthosomal and postoesophageal. Each center contains one or more cell types. Reprints.