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General Aspects

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Taxonomy

Ticks are members of the same phylum (Arthropoda) of the animal kingdom as insects, but are in a different class. The subphylum Chelicerata includes the class Arachnida, which again contains several subclasses. The subclass Acari (syn. Acaria, Acarina, Acarida) includes ticks.

There are two well established families of ticks, the Ixodidae (hard ticks), and Argasidae (soft ticks), (Sonenshine, 1991).

Taxonomy

Classification

e.g.Dermacentor variablis

Kingdom

Animalia

Phylum

Arthropoda

Class

Arachnida

Subclass

Acaria (Acari, Acarina, Acarida)

Order

Anactinotrichidea (= Parasitoformes)

Suborder

Ixodida (= Metastigmata)

Family

Ixodidae

Genus

Dermacentor

Species

Dermacentor variablis

A characteristic of the Acarines is the extreme fusion of body segments, in contrast to the known three body segments head, thorax and abdomen in insects.

Body segments of ticks

The Acari are subdivided into the order Parasitiformes and Acariformes. The order Parasitiformes to which ticks belong have stigmatal pores on the podosoma part (leg-bearing portion) and free articulated coxae (Sonenshine, 1991).

Their suborder is Metastigmata, because their stigmen can be found behind the coxa III or behind coxa IV. The members are obligate blood-sucking parasites. All of them have in common the Haller's organ, a complex sensory organ, on tarsus I, a toothed hypostome, a peritreme around the stigmen and chelicera of only two joints.

All adult Metastigmata mate on their host, before lying eggs on the ground. These develop into 6 legged larvae, 8 legged nymphs and adults. Adult tick size spans between 2.2 mm (unfed male) to 13 mm (fed female).

In the most common ticks feeding takes place on pet animals.

Typical characteristics of ticks

  • All stages of the developmental cycle of all kind of ticks parasitic on vertebrates
  • Stigma behind coxa IV
  • Ventral toothed hypostom
  • Peritreme around the stigmen
  • Haller`s organ on tarsus I
  • Stages: larvae, nymphs, adults
  • Ixodidae (hard ticks) and Argasidae (soft ticks)

The order Metastigmata comprises 3 families: the Ixodidae (hard ticks), the Argasidae (soft ticks), and the Nuttalliellidae. The two major tick families are Ixodidae and Argasidae (Pfister, 2006). Nuttalliellidae represents only one single species (Nutalliella namaqua; found in South and South-West Africa as a parasite of small mammals).

The accurate identification of tick species is an important factor in the detection and diagnosis of tick-borne diseases and is a prerequisite for tick control (Cupp, 1991).

   

Further information

  • Cupp EW: Biology of Ticks. Vet Clin North Am Small Anim Pract. 1991, 21, 1-26
  • Pfister K: [Arthropodes in Ruminants.] In: Schnieder T (ed.): Veterinärmedizinische Parasitologie. 6th edn., 2006, Parey in MVS, Stuttgart, pp 235-292 [in German]
  • Sonenshine DE: Biology of Ticks. Part 1, 1991, Oxford University Press, New York

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