Mohamed A. Roshdy

Argas (Persicargas) arboreus: Juvenile hormone analog termination of diapause and oviposition control

Abstract The juvenile hormone analog acetaldehyde, 2-(2-ethoxyethoxy) ethyl p -(methylthio) phenyl acetal, topically applied in a concentration of 10 μg/5 μl acetone/female, terminated diapause and induced vitellogenesis and oviposition in fed female Argas (Persicargas) arboreus Kaiser, Hoogstraal, and Kohls (Argasidae). This is the first reported hormonal termination of diapause in argasid ticks. A full bloodmeal and mating were critical factors controlling oviposition in nondiapausing females, and may enhance juvenile hormone activity. Experiments suggest that tick bodies possess sites of hormonal activities similar to those in other arthropods.

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.

Ultrastructure of granule secretion in salivary glands ofArgas (Persicargas) arboreus during feeding

The granule secretion process inArgas (Persicargas) arboreus salivary gland alveoli during feeding is described. Cells within an alveolus are not synchronized with respect to secretion. The secretory process is probably under neural control. In type II alveoli, large granules are released by apocrine secretion and small granules by merocrine secretion. Apocrine secretion is divided into three phases for descriptive purposes: (1) crawling of the tick on the host initiates formation of an intracellular membrane system connected to both the apical cell membrane and the membrane surrounding the granule, (2) breakdown of this membrane system releases granule contents and cytoplasm into the alveolar lumen and the salivary duct, and (3) spent secretory cells undergo a reduction in size. This granule secretion process has a significant adaptive value to the rapid repeated feeding of argasid ticks. Pharmacologically active substances are synthesized by secretory cells between feedings and are stored in the cell as granules isolated by a limiting membrane. The process is initiated by the presence of the host. It is rapid; not all of the secretory cells secrete during a single feeding and those that do remain intact enough for synthesis of new granules are used for repeated feedings.

The Functional Morphology of Haemaphysalis Spiracles (Ixodoidea: Ixodidae)

SummaryThe spiracular structure of Haemaphysalis hoodi, H. kinneari, H. punctata, H. longicorms, and Boophilus microplus is described as seen by light and scanning electron microscopy (SEM), and is discussed in relation to previous reports on the structure and function of tick spiracles. Surface pores and a prominent lip-guarded ostium in the spiracular plate are readily observed by SEM and also in histological sections. Goblets in the peripheral part of the spiracular plate open to the exterior by pores and connect the hypodermal epithelium with fine canals apparently containing sensory sensilla. Experimental CO2 and cyanide gas exposure provide evidence of a mechanism for opening and closing the spiracle and involving the ostial lip and atrial valve. This mechanism appears to depend on hemolymph pressure and action of atrial and other body muscles.

Nuttalliella namaqua (Ixodoidea: Nuttalliellidae): Spiracle structure and surface morphology

The structure and surface morphology of the femaleNuttalliella namaqua spiracle are described with the aid of light and scanning electron microscopes. The spiracle, located posterolaterad to coxa IV, consists of a convex fenestrated plate lacking the marginal peritrime of ixodids, and a small, concave macula with a crescentic ostium enclosed by a lip. Ramifying pedicels around interpedicellular spaces are easily observed through the wide surface fenestrae. Below the ostium, a subostial space leads to a wide atrial chamber from which tracheal trunks extend. A thick-walled valvelike projection guarding the connection between the subostial space and atrial chamber probably controls air passage aided by the valve and atrial muscle action. Nuttalliellid spiracles have structural properties of both Ixodidae and Argasidae. However, the fenestrated plates are unique and differ significantly from the plates of Ixodidae and Argasidae.

Bat ticks of the genus Argas (ixodoidea: Argasidae)

SummaryThe surface structure and histology of the ventral paired grooves of Argas (Chiropterargas) boueti and A. (Carios) vespertilionis are described as seen by scanning electron microscopy (SEM) and the light microscope. The groove is a narrow, integumental cleft. The thickened, opposed walls bear rows of fine lanceolate or conical projections which may interlock when the integument is contracted. Groove expansion and contraction is apparently affected by ventral muscle bands. The function is uncertain, but paired grooves may assist in the defecation process.

Structure of the nymphal spiracle and its formation in the pharate adult Haemaphysalis (Kaiseriana) longicornis neumann (ixodoidea: Ixodidae)

SummaryThe surface structure and histology of the nymphal and developing pharate adult Haemaphysalis (Kaiseriana) longicornis and of nymphal Boophilus microplus spiracles are described by light and scanning electron microscopy (SEM). Surface pores and ostial aperture in the nymphal spiracular plate are observed by SEM (H. longicornis and B. microplus) and in histological sections (H. longicornis). Formation of the pharate adult tick spiracle starts 2 or 3 days after nymphal detachment from the host and is completed on day 14 or 15 when the adult is ready to emerge. During this interval, hypodermal cells beneath the nymphal spiracular plate differentiate into the pharate adult spiracle components and form a thickened, folded edge around the ostial aperture, which contains detached nymphal tracheae. The developing adult spiracular plate shows goblets and interpedicellar spaces and a lip-guarded ostium. The molting process of the adult tick spiracle is more simple than that of insects having specialised spiracular plates.

Sensory Receptors in Ticks and Mites

Sensory receptors in Acari are poorly known although extensive research has been reported on other Arthropoda, particularly Insecta. Our investigations of the setae on the first tarsus of the hard ticks, Amblyomma americanum (L.) and Haemaphysalis (Alloceraea) inermis Birula revealed the presence of chemo- and mechanoreceptors, judging from ultrastructural characteristics. A consistent pattern of distribution of tarsal sensilla in the region of Haller’s organ was observed, by scanning electron microscopy (SEM), in the different species and life stages. Presumably chemoreceptive sensilla, resembling one type in the ticks, were found on the first tarsus of the mesostigmatid mite, Macrocbeles muscaedomesticae (Scopoli).

THE SUBGENUS PERSICARGAS (IXODOIDEA: ARGASIDAE: ARGAS): A. (P.) ARBOREUS CENTRAL NERVOUS SYSTEM ANATOMY AND HISTOLOGY

The anatomy and histology of the adult Argas (Persicargas) arboreus central nervous system are described and compared with these properties in other ticks. The single, integrated, central nerve mass (CNM) is formed by a fused supra-esophageal part (protocerebrum, cheliceral ganglia, palpal ganglia, and stomodeal pons) and a subesophageal part (4 pairs of pedal ganglia and the complex opisthosomatic ganglion). Single peripheral nerves (pharyngeal and recurrent) and paired peripheral nerves (compound protocerebral, cheliceral, palpal, pedal and opisthosomatic) extend from the CNM to body organs and appendages. Optic nerves, described in other Argas species, are not found in A. (P.) arboreus. Histologically, the CNM is enclosed by a thin-walled periganglionic blood sinus and invested by a collagenous neural lamella followed by a perineurial layer composed of glial cells and containing fine reticular spaces, a cortical layer of association, motor and neurosecretory cell bodies and glial cells, and inner neuropile regions of fiber tracts forming 5 horizontal levels of connectives and commissures.

Observations on the subgenus Argas (Ixodoidea: Argasidae: Argas). 18. Haller's organ roof and anterior pit setae

Adults of 18 of the 22 species constituting the subgenus Argas, which parasitize birds nesting and resting in rocky habitats in each faunal region of the world (15 species) or in trees (e species) (2 Neotropical, 1 Nearctic), were studies by SEM. In each except three Neotropical species, the nine setae of the anterior pit of tarsus I are arranged in an anterior group (1 serrate, 1 setiform, 1 conical) and a posterior group (2 fine, e porose, 2 grooved), or the two groups are more or less confluent. Abnormally, additional setae may occur on one or both tarsi of a single specimen. In one Neotropical species, only the three anterior group setae are present. In three Neotropical species, only these three setae and a fourth seta are present (whether 6 or 5 additional setae are concealed within the tarsal structure should be investigated). The Hallers organ capsule is entirely open (unroofed) (3 species), roofed posteriorly and open anteriorly (7 species), or mostly roofed by a plate which is pierced by one large aperture and by more or less numerous, small, or medium-sized perforations (8 species plus one other not studied by use). This study suggests that the structure of Hallers organ has evolved in different lines in response to a multiplicity of biologic al factors related to the behavior and habitat of individual species.