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Loveridge (1928) ambiguously associated 0. moubata with giraffes in Tanganyika, and Santos Dias (1952, 1953, 1954K) men tioned small numbers of nymphal and adult specimens from lion, Lichtenstein's hartebeest, waterbuck, and scaley anteater. Further data for these exceptional records are desirable.
Heisch (1950A) obtained negative results when he attempted to induce 0. moubata in Kenya to bite house rats, Rattus rattus, placed in huts for experimental purposes. Wild rodents from tick-infested Tanganyika dwellings gave no evidence of spirochetes when tested in the laboratory (Geigy and Mooser 1955).
van den Branden and Van Hoof (1922) fed laboratory specimens on the fruit bat, Eidolon helvum.
No other wild mammals have been reported actually to have been observed as hosts of 0. moubata in nature. The fact that the burrow-inhabiting warthog and the domestic pig each serve as a host of this tick is of special interest. Heisch and Grainger (1950) have concluded that before 0. moubata became "domesticated" it inhabited large burrows of wild animals.
Roubaud (1916) conjectured that some of the several external parasites of warthog and man alike may be attracted to these hosts because of their hairless skin. This interesting theory is prob ably not now tenable for 0. moubata in the light of present knowledge.
In review, it appears that large burrows of wild animals, among which those of the warthog are the most common, are the favorite and quite possibly the original habitat of 0. moubata. It should be borne in mind, however, that those populations of this tick inhabiting wild animal burrows may possibly represent a different physiological or biological race, or a distinct sub species. It would be of value to determine the domesticability of "wild" populations.
Recently, Heisch (19540) has noted that ticks from burrows are more difficult to feed on laboratory animals than are those from domestic habitations, Ceigy and Mooser (1955) observe that bush ticks are more blue gray in color, move more quickly, attach to the host and suck blood more quickly, and are hardier in cap tivity than specimens from domestic populations of 0. moubata.
Contrary to Heisch's experience, they state that wild specimens "adapt themselves to feeding on mice and guineapigs easier than house ticks".
Wild Reptile Hosts
Bedford (1934) listed several collections from South African tortoises. Theiler (unpublished) has records of nymphs and adults from four species of South African tortoises, Testudo oculifera, T. verreauxii, T. schồnlandi, and Homopus femoralis from Kimberley and Wodehouse Districts and from Namaqualand. Theiler considers tortoises to be exceptional hosts.
Rodhain (1920,1922B,C) found that blood of lizards, geckos, and snakes is easily digested by 0. moubata. Although nymphs that had fed on snakes died in larger numbers than those that had fed on mammals, survivors reached the same size as mammal-fed individ uals. Chameleon blood is initially very toxic, and digestion is slow and difficult. Though many ticks die after feeding on cha meleons, a few do become adapted to it. Individuals that had fed exclusively on chameleons for sixteen months subsequently fed on mice when allowed to do so. Van Hoof (1924) reported similar findings. As already stated, tortoises sometimes are infested in South Africa, but no other collections from coldblooded vertebrates in nature have been reported.
Life history details have been studied and reported by Dutton and Todd (1905A), Newstead (1905A,B,C,1906A,B) and Wellman (1906C, D,1907A). These were reviewed by Nuttall et al (1908). Subsequent observations were reported by Cunliffe (1921), Jobling (1925), and Pierquin and Niemegeers (1953)*. Other contributions on specialized phases are noted below. Some discrepancies in observations exist, but the broad outlines of the life cycle are well established. Critical and restrictive factors are poorly known and no observa tions on the life cycle under natural conditions have been undertaken. The natural history of o. moubata is gradually being elu
*The dates of publication of these reports will not be repeated in the life cycle section,
cidated, but each new observation suggests how many other details are yet to be known.
A summary of the life cycle is as follows: Copulation is effected by transfer of a male spermatophore to the female, after which the female indulges in a rapid blood meal and subsequently deposits a small batch of unusually large eggs in or on the soil. After the larva emerges it remains nonmotile and nonfeeding till the nymphal stage some hours or days later. The active nymph, after a short rest, feeds on an available host for about half an hour, then retreats to the soil or a crevice to digest its meal. Subsequently, the nymph molts, usually four or five times, with a similar pattern of resting, feeding, and resting between each ecdysis. Sexually mature adults emerge from the last molt and normally mate shortly afterwards. The female feeds two days later and several days afterwards deposits a batch of eggs. Adult hid ing and feeding habits are like those of nymphs, Seven feedings and egg batches appear to be maximum in one female's lifetime, A minimum of about two and a half months is necessary to complete the life cycle, which normally is probably considerably more extended than this. Apparently these ticks do not voluntarily wander far in search of food and considerable numbers may develop in a single building or large animal burrow.
The mating behavior of 0. moubata was described by Nuttall and Merriman (1911) but the account of mechanism of insemination has been augmented by Robinson (1942B). The development of the sperm has been described by Samson (1909).
In the male the spermatids travel down the vas deferens either in a continuous stream or are aggregated in rounded pellets, each containing a few hundred male elements. As stated by Robinson and Davidson (1914) (for Argas persicus), it is probable that the male accessory glands secrete the spermatophore case into which these elements pass.
[ According to Robinson, the spermatophore is not chitinous. It completely dissolves in strong KOH solution at 150°C., and becomes red in Millon's reagent; therefore it is probably largely protein. 7
In order to mate, the male crawls beneath the female and clings to her so that the two ventral surfaces are in apposition. After dilation and stimulation of the female orifice by insertion and movement of male mouthparts, a spermatophore issuing from the male genital aperture is grasped by the male's_mouthparts and transferred to the female genital aperture. [Coxal fluid is emitted by the male during the course of these activities ac cording to Nuttall and Merriman, but Dr. G. E. Davis and Dr. W. Burgdorfer state (conversation) that they have not observed this. It is possible that coxal fluid may or may not be emitted at this time, due either to copiousness of supply or to degree of excitement.]
The spermatophore is bulb shaped (Figure 42) as it issues. After the male applies it to the female aperture, contraction and evagination force out the long neck with the capsules (Figure 43) that are inserted into the aperture. Most of the spermatids are forced into the capsules but the bulb remains outside the female aperture and drops off sooner or later. As many as ten bulbs have been seen in situ. The neck dries and twists, making an effective seal at the capsule closure. After five days at 300C., the now mature sperms escape into the uterus by rupture of the capsule wall. For further details, see Robinson (1942B).7
As stated below, the initial fertilization usually occurs shortly following molting to the adult stage, and females first feed about two days afterwards, They may feed before mating, presumably chiefly when males are not readily available. How ever, according to Jobling, the period of time between fertiliza tion and feeding has no effect upon the period between feeding and oviposition,
Figure 42. Invaginated, bulb-shaped spermatophore
as it issues from male genital aperture. Figure 43. Evaginated spermatophore, with neck and capsules, after having been applied to female uterus.
ORNITHOD OROS MOUBATA SPERMATOPHORE
[After Robinson (1942) 7