The subgenus Persicargas (Ixodoidea: Argasidae: Argas). 23. Fine structure of the salivary glands of unfed A. (P.) Arboreus Kaiser, Hoogstraal, and Kohls.

Salivary glands of the unfed adult Argas (Persicargas) arboreus (family Argasidae) contain 2 types of alveoli, one nongranular and one granule-secreting. The fine structure of the nongranular alveolus is similar to that of the family Ixodidae. In the granule-secreting alveolus, the presence of 3 types of secretory cells, each with morphologically distinct granular inclusions, confirms histological and histochemical observations on argasid salivary glands. Epithelial cells with numerous membranous infoldings, mitochondria, microtubules, and a complex canalicular system probably concerned with fluid regulation and secretion are located between granule-secreting cells and form caps over their basal regions. The luminal border of both secretory and epithelial cells is microvillate. The alveolar lumen leads into the chitinous alveolar duct which lacks the complex valvular structure of ixodid alveoli. Axons containing neurosecretory material occur in both nongranular and granule-secreting alveoli and probably control salivary secretion.     

The subgenus Persicargas (Ixodoidea: Argasidae: Argas). 25. Effect of temperature on diapause termination in female A. (P.) arboreus Kaiser,Hoogstraal and Kohls

The effect of constant 26, 30, 34, and 37 C temperatures on diapause incidence (percentage of diapause females) and intensity (duration of preoviposition period) was compared in field-collected (FC) and laboratory-reared (LR) F₁ and F₂ female A. (P.) arboreus. Diapause incidence, 89–100%, and intensity 115–133 days, in the FC were high at all temperatures except at 30 C when the intensity was reduced (84 days). Diapause incidence, 91–94%, and intensity, 132–137 days, in LRF₁ were high at 26 and 30 C. At 34 and 37 C, both (33% and 78 days) were lower than in FC and LRF₁ at 26 and 30 C. Diapause incidence was always lower in LRF₂ than in FC and LRF₁ and decreased as the temperature increased (58, 30, 17, and 0%, respectively). Diapause intensity in LRF₂ at 26 C (133 days) was high and similar to that in FC and LRF₁ at 26 C but was low at 30 and 34 C (84 and 87 days, respectively). In all groups, diapause intensity was higher in females kept outdoors (191–218 days) than in those held in the laboratory. The results suggest that rearing in the laboratory caused an increased sensitivity of diapause LRF₁ and F₂ females to high temperature.     

Neuropathogenic properties of Argas (Persicargas) walkerae larval homogenates

Several tick species have been demonstrated, described, or suspected to cause paralysis in their host during the repletion process, presumably by impairing neurotransmission. The resulting polyneuropathy gradually spreads to the upper limbs causing incoordination and ends in respiratory failure. This form of paralysis is commonly confused with Guillain-Barrè syndrome, botulism and myasthenia gravis and although the clinical symptoms of these diseases are similar, it is not clear whether the pathogenesis is also the same. During this study we investigated the mechanism of paralysis by the tick Argas (Persicargas) walkerae by determining the effect of larval homogenates on both potassium-stimulated (calcium-dependent) and veratridine-stimulated (external calcium-independent) release of [3H]glycine from crude rat brain synaptosomes. The results indicated that larval homogenates inhibited both processes. These findings are reconcilable with the results obtained for two other paralysis-causing tick species, Ixodes holocyclus and Dermacentor andersoni, which were indicated to cause paralysis by decreasing the synthesis or release of acetylcholine at the neuromuscular junction.     

The subgenus Persicargas (Ixodoidea: Argasidae: Argas). 22. The effect of feeding on hormonal control of egg development in Argas (Persicargas) arboreus

The blood-meal is essential to complete ova development by supplying nutrients and by stimulating hormone production in mated female Argas (Persicargas) arboreus. Within 3 days after feeding, the hormone is synthesized in the nerve ganglion and afterward is released into the hemolymph. Isolating the ovaries by ligation from the nerve ganglion during the hormone synthesis period interfered with ova development. Injecting an extract of nerve ganglia from 3-day-fed, mated females and of hemolymph from 4-day-fed, mated females into mated, recently fed females induced the same degree of ova development in their isolated ovaries as in fed, mated control females. Injecting nerve ganglion extract from 3-day-fed, mated females into mated, unfed females did not induce ova development.     

Biochemical and physiological studies of certain ticks (Ixodoidea): specific gravity of hemolymph and coxal and gut fluids of Argas (Persicargas) persicus and Argas (Persicargas) arboreus (Argasidae)

Specific gravity (sp. gr.) of cell-free hemolymph and gut and coxal fluids was determined at different states of the gonotrophic cycle (unfed + 15 days, engorgement day before and after coxal fluid emission, engorgement + 1 day, oviposition day, and oviposition completion + 1 day) of female Argas (Persicargas) persicus and A. (P.) aboreus (Argasidae). The patterns of hemolymph and gut fluid sp. gr. change differed from each other during the gonotrophic cycle, but both patterns were similar in the 2 Argas species. Hemolymph sp. gr. decreased to a minimum one day after feeding (1.0085 and 1.0081 for persicus and arboreus, respectively), and increased through oviposition to a maximum on oviposition + 1 day (1.0187 and 1.0221). Minimum gut fluid sp. gr. occurred on engorgement day before coxal fluid emission (1.0565 and 1.0697). Afterward, gut fluid sp. gr. increased to a maximum on engorgement day + 1 for persicus (1.1089) and on oviposition day for arboreus (1.0973), and then decreased during oviposition in both species. In each tested state of each species, the sp. gr. was consistently higher in gut fluid than in hemolymph. In each species, coxal fluid and hemolymph sp. gr. were the same on engorgement day.     

The Mechanism of Oviposition in Argas (Persicargas) Walkerae (Acari: Argasidae)

The process of oviposition in A. walkerae was observed and found to be a sequence of exactly coordinated, interlocking events independent of the age of ticks. Egg-laying always commenced with numerous dorso-ventral movements of the capitulum. The pedipalps were spread during the last dorso-ventral movement and lowered to the ventral body wall embracing the genital aperture on both sides. Simultaneously, the cuticular sac of Gene's organ emerged and immediately everted maximally. Immediately afterwards the vestibulum vaginae prolapsed from the genital aperture touching the cuticular sac. The vestibulum vaginae handed over an egg to the cuticular sac after a brief contact. Then the vestibulum vaginae invaginated, the pedipalps closed and the cuticular sac was retracted. Finally, the capitulum very frequently moved up and down and the free egg was pushed in front of the ticks. The total time of laying an egg averaged 27min in both 4-week-old and 12-month-old ticks. In 4-week and 12-month-old ticks, egg-laying was preceded by a mean preoviposition period of 6.1 days and 7.5 days, respectively, while the mean oviposition was completed in 14 and 10 days and the average egg totals were 119 and 103.