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On the adaptation of ticks to the habits of their hosts1

Published online by Cambridge University Press:  06 April 2009

George H. F. Nuttall
George H. F. Nuttall
Affiliation:
(From the Quick Laboratory, University of Cambridge.)
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Extract

A consideration of the facts presented in the foregoing pages appears to warrant certain conclusions which must, however, be regarded in part as provisional and subject to revision when our knowledge of the various species of ticks has become more extended. The views here expressed may prove of practical use in the study of the Ixodidae.

The Argasidae represent the relatively primitive type of ticks because they are less constantly parasitic than are the Ixodidae. Their nymphs and adults are rapid feeders and chiefly infest the habitat of their hosts. In certain Argasidae (O. moubata and O. savignyi) the disadvantage of their possessing an “active” larval stage has resulted in the development of an “inactive” larva, i.e. the young nymph being the first to suck blood. In O. megnini we have a considerable adaptation brought about by the difficulty there must be in the tick entering the small aperture of the ear more than once. Owing to the Argasidae infesting the habitats of their hosts, their resistance to prolonged starvation and their rapid feeding habits, they do not need to bring forth a large progeny, because there is less loss of life in the various stages, as compared to Ixodidae, prior to their attaining maturity.

The Ixodidae are more highly specialized parasites than the preceding. The majority are parasitic on hosts having no fixed habitat and consequently all stages, as a rule, occur upon the host. In the genus Ixodes we find an adaptation of certain species according to the habits of the hosts upon which they are parasitic. In the species which usually occur upon wandering hosts both sexes are found upon the host, whereas in other species which occur on hosts possessing more or less fixed habitats the males are rarely or never found upon the host. The males of species of Ixodes, both sexes of which occur upon the host, are characterized, as a rule, by the possession of hypostomes with prominent teeth, the reverse being the case in forms wherein the males do not occur upon the host. Where species occur upon a wandering host it is essential, for their propagation in nature, that both sexes should be carried about upon the host.

Type
Research Article
Information
Parasitology , Volume 4 , Issue 1 , March 1911 , pp. 46 - 67
Copyright
Copyright © Cambridge University Press 1911

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References

2 The main structural differences are described by Nuttall and Warburton (1908) in Ticks: a Monograph of the Ixodoidea, by Nuttall, Warburton, Cooper and Robinson, Part I, p. 1.

1 Ornithodorus megnini excepted.

2 megnini excepted.

1 See Ticks, Part I, p. 39, where the bats are listed. A variety infests penguins at Queenstown, Cape Colony.

1 Although I have examined many bats, I have never found A. vespertilionis adults and nymphs upon them. On the other hand, larvae, in various stages of repletion, were not infrequently encountered. I conclude from this that the larval stage must remain attached to the host for some days at least. Doubtless, the duration of parasitism is influenced by the surrounding temperature.

2 It is reported that Starcovici once found reflexus larvae on the horse in Boumania (vide Ticks, Part I, p. 27), but I feel warranted in doubting the statement.

1 See footnote p. 48.

1 Reproduced from Salmon and Stiles, 1901, figs. 99 and 102 (17th Ann. Rep., B.A.I., U. S. Dept. Agricult.) and from Ticks, Part I.

1 The variations in this structure in male Ixodes will be discussed presently.

1 o and L signify that nymphal and larval stages only were found.

1 See Note on p. 67.

1 Nymphal and hrval stages ere known in many of these species.

1 As a further confirmation of the views expressed in this paper, I would state that we have recently (March, 1911) discovered a male of Ixodes hexagonus in the nest of a hedgehog. This is the first male we have captured, whereas we possess hundreds of females, nymphs and larvae found on various hosts. The rarity of the male is rendered evident by the fact that there is not a single specimen of a male in the Museums in London, Paris and Berlin.