Acarology Lecture 7 PDF

Acarology “516 ZOO” Lecture 7 Dr. Osama B Mohammed & Dr. Jawahir ALGhamdi 1  The Mesostigmata are a large group of mites, the majority of which are predatory, but a small number of species are important as e...

Acarology “516 ZOO” Lecture 7 Dr. Osama B Mohammed & Dr. Jawahir ALGhamdi 1  The Mesostigmata are a large group of mites, the majority of which are predatory, but a small number of species are important as ectoparasites of birds and mammals. Mesostigmatid mites have stigmata above the coxae of the second, third, or fourth pairs of legs. Sub-order MESOSTIGM They are generally large, with usually one large, ATA (Gamesid sclerotized shield on the dorsal surface and a series of smaller shields in the midline of the ventral surface. T mites) The legs are long and positioned anteriorly. Some are host-specific, but most parasitize a range of hosts. There are two main families of veterinary interest, the Macronyssidae and Dermanyssidae, and four families of minor interest, the Halarachinidae, Entonyssidae, Rhinonyssidae and Laelapidae. Family MACRONYSSIDAE These are relatively large, blood-sucking ectoparasites of birds and mammals, of which Ornithonyssus, in birds, and Ophionyssus, in reptiles, are of veterinary importance. Only the protonymph and adult stages feed. The mites have relatively long legs and can be seen with the naked eye. Family DERMANYSSIDAE Species of the genus Dermanyssus are blood-feeding ectoparasites of birds and mammals. They are large mites with long legs, greyish white, becoming red when engorged. Family HALARACHNIDAE Mites of the subfamily Halarachinae mammals’ respiratory tracts. Pneumonyssus is found in the nasal sinuses and nasal passages of dogs. Members of the subfamily Riallietiinae are obligate parasites in the external ears of mammals. Raillietia is found in the ears of domestic cattle. Family ENTONYSSIDAE Mites of the family Entonyssidae are found in the respiratory tract of reptiles. Entonyssus, Entophionyssus, and Mabuyonysus are found in the trachea and lungs of snakes. Family RHINONYSSIDAE Most species are parasites of birds’ nasopharynxes. Sternosoma occurs worldwide in various domestic and wild birds, including canaries and budgerigars. Family LAELAPIDAE Species of the genera Hirstionyssus, Haemogamasus, Haemolaelaps, Echinolaelaps, Eulaelaps, and Laelaps are blood-feeding parasites of rodents and are found worldwide. Androlaelaps, the poultry litter mite or nest mite, can occur in large numbers in chicken-house litter.  Class PENTASTOMIDA The adults of this strange class of aberrant arthropods are found in the respiratory passages of vertebrates and resemble annelid worms rather than arthropods. The genus Linguatula is of some veterinary significance. Adult parasites occurring in the nasal passages and sinuses of dogs, cats, and foxes. Pentastomids are up to 2.0 cm long, transversely striated, and shaped like an elongated tongue (Fig. under). They have a small mouth and tiny claws at the extremity of the thick anterior end. Pentasomid: female Linguatula serrata (redrawn from Soulsby, 1982). It is commonly believed that the first fossil records of the Arachnida (and the Acari) originate in the late Silurian–early Devonian periods (c.425 mya) in the form of a pulmonate trigonotarbid (Arachnida, Trigonotarbida), which is now extinct. Dunlop and Selden (2009) report that the oldest mite fossil is from the Devonian (410 mya), while the age of scorpion and spider fossils is 428 and 312 mya, respectively. The advent of the Acari probably also relates to the latter part of the evolution of the arthropods, with diversification having occurred about 200 million years earlier in the Cambrian period (Gould, 1989; Walter and Proctor, 1999). Fossil records show that the terrestrial Arachnida acquired respiratory organs of different types at different times during the transition from the marine environment onto land, as in the scorpions, trigonotarbids, etc. Formally, this pattern of developmental behavior contrasts with the hypothesis of the monophyletic origin of Arachnida (Bergstrom, 1979).  The fossil records now available seem to indicate that the Acari had achieved a certain amount of diversity by the early to mid- Devonian (Hirst, 1923a; Woolley, 1961; Norton et al., 1988; Evans, 1992; Subias and Arillo, 2002), which suggests that they colonized terrestrial environments as early as the late Silurian. Moreover, in the early Devonian, all fossil Acari now known belonged to the superorder Acariformes (Walter and Proctor, 1999), and the fossil records of the Parasitiformes dating to the late Cretaceous (Witalinski, 2000; Poinar and Brown, 2003); the parasitiform Trigynaspida may date to as early as the upper Triassic (c.220 mya) (Kim, 2004). Studies of mitochondrial phylogeny have shown that the orders and classes of spiders, scorpions, mites, and ticks diversified in the late Palaeozoic (Jeyaprakash and Hoy, 2008, 2009). Thanks.. 12