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  • eyes  (2)
  • Rhipicephalus evertsi mimeticus  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Morphology of the foveal glands and foveae dorsales in male Hyalomma truncatum and Rhipicephalus evertsi mimeticus ticks (Acari; Ixodidae) before and during feeding (1996)
    Springer
    Experimental and applied acarology 20 (1996), S. 511-532 
    Details
    ISSN: 1572-9702
    Keywords: Male ticks ; Rhipicephalus evertsi mimeticus ; Hyalomma truncatum ; foveal glands ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of the foveae dorsales and foveal glands in unfed and attached male Hyalomma truncatum and Rhipicephalus evertsi mimeticus ticks was studied. Both species are provided with a paired foveal gland system, which is similar in unfed as well as in attached ticks. This gland system consists of the fovea dorsalis with pores and pore tubes as the external part, the foveal neck zone as a link between the fovea dorsalis and the lobes of the gland and the bulbous lobes as the innermost part. The fovea dorsalis is located on either side of the dorsal midline in the midsection of the body and appears as a roundish plate containing 15±6.5 and 21±7 slit-like pores in R. evertsi mimeticus (n=210) and H. truncatum (n=210), respectively. Each pore leads into a cuticular lined channel containing a pore tube. Below each fovea, the foveal neck zone is located within a groove of the cuticle and consists of the termini of the pore tubes which enlarge basally to form a cup-shaped ampulla each. Furthermore, secretory lobes are located below the foveal neck zone. Each lobe consists of secretory cells and a central excretory duct which leads into the ampulla. The ducts are lined with microvilli. The secretory cells contain numerous vesicles of varying size with one or more granules. In male ticks of both species the secretory lobe cells remained unchanged in size, structure and granule content irrespective of whether they were unfed or attached for up to 30 days. Axons occur in the fascicles between the secretory lobe cells containing numerous neurosecretory vesicles. A possible role of the foveal glands in the production of pheromones is hypothesized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048284
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Morphology of the Eyes in adult Hyalomma Truncatum Ticks (Acari: Ixodidae) (1997)
    Springer
    Experimental and applied acarology 21 (1997), S. 21-39 
    Details
    ISSN: 1572-9702
    Keywords: Adult ticks ; Hyalomma truncatum ; eyes ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The eyes of Hyalomma truncatum ticks are morphologically similar in both sexes. They appear aspaired hemispherical structures situated dorsally between the first and second pair of legs on thelateral scutal margin. Each eye consists of a lens and photoreceptor cells, which are separated by afine fibrillar layer and the hypodermis. The lens contains numerous channels which open beneaththe epicuticle, converge uninterruptedly to the interior of the lens and end below the fine fibrillarlayer. The inner closure of the lens is formed as an oval plateau with a cone-like projectionsituated caudolaterally and eccentrically to the longitudinal axis of the lens. The hypodermis is asingle layer of cells, situated immediately below the fine fibrillar layer. Beneath the hypodermis,directly below the cone-like projection of the inner lens are the photoreceptor cells localized in arosette-like arrangement. Facing the hypodermis, each photoreceptor cell is provided withnumerous microvilli. The microvilli consistently border the microvilli regions of other cells atdifferent angles but are always oriented at a right angle to the lenticular channels. Thephotoreceptor cells are unipolar neurons, whose axons arise from the basal portion of the cell andjoin to nerve fibre bundles forming the optic nerve. It is concluded that the eyes in adult H.truncatum ticks possess all the structures necessary to perceive and conduct light stimuli andvisual signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018489208924
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    On the visual perception of the eyes in adult Hyalomma truncatum ticks (Acari: Ixodidae) (1997)
    Springer
    Experimental and applied acarology 21 (1997), S. 307-315 
    Details
    ISSN: 1572-9702
    Keywords: Ticks ; Hyalomma truncatum ; visual signals ; perception ; eyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adult Hyalomma truncatum ticks with uncovered and foil-covered eyes were exposed to an upright-positioned rectangle as a target giving a luminance contrast ratio of 5:1 at a sun-simulating radiation. The transmission rate of the foil was less than 0.003%. Significantly (p≤0.05) more locomotorally active ticks with uncovered eyes (36.6%) responded to the target than ticks with foil-covered eyes (7.3%). When the rectangle was illuminated by monochromatic light at wavelengths ranging between 420 and 648 nm, the target induced a positive scototaxis in ticks with uncovered eyes regardless of the wavelength range. In contrast, ticks with covered eyes did not exhibita positive scototaxis at wavelength ranges of 553–585 and 608–648 nm and very few ticks responded only to other wavelength ranges. The results indicate that the eyes are the only or at least the most essential sense organs in the visual system of adult H. truncatum ticks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018459324370
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    Paper (German National Licenses)
    Fulltext
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