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In various editions of Brupt's 'Precis,' 0. moubata is con. sidered as an outdoor as well as an indoor species. There is, however, no published evidence to support the supposition that this species normally lives away from huan structures, except in large animal burrows and in pigsties. Rare exceptions, such as ticks remaining in the area after a building is destroyed, or dropping from a bedding roll during transit, must be expected. Further search may, of course, show that the tampan has a broader range of habitats than present evidence indicates.
A gradually increasing body of information indicates the not uncommon occurrence of 0. moubata in large animal burrows through. out tropical and southern Ifrica (see HOSTS above). The relation. ship of these populations to those of human habitations awaits determination. The environment of infested burrows has been only briefly described and it is not known whether wild populations have the same temperature and humidity requirements as domestic
In Tanganyika burrows, ualton (1953) observed tampans clinging to the roof close to the entrance as though waiting for some animal to squeeze past. Ticks were found among the hair of the back of warthogs shot in the early morning. In the burrows, temperature was 759F. and relative humidity of the soil 77%. Other infested Tanganyika burrows examined by Geigy and Mooser (1955) with thermohygrometers showed that the microclimate of these holes corresponded closely to that observed by them in infested native huts (details not stated).
Discovery of nuerous specimens in large burrows in several widely scattered parts of Kenya has led Heisch and Grainger (1950) to speculate on the relationships between wild and domestic populations of eyeless tampans. The ticks were obviously breeding in these burrows that originally had been dug by antbears and later were inhabited by porcupines or warthogs. Other specimens were found in large burrows on a long-isolated Lake Naivasha island seldom visited by man. Heisch and Grainger conjecture that large burrows were the original or primitive home of the eyeless tampan and that it later became adapted to human habitations. The several reports of Q. moubata from burrow.inhabiting warthogs, porcupines.
and antbears, already mentioned in the section on HOSTS, bolster this theory. Further indirect support is gained from the peva_ lence of the warthog's relative, the domestic pig, as a host. The tampan of human habitations may have evolved from populations formerly parasitizing burrowing, wild pigs, and they may still retain some pedilection for pigs. As already noted, it is also possible that "wild" and "domestic" populations represent separate biological or physiological or even unrecognized morphological entities.
Predators and Enemies
Chickens, rats, and mice are said to feed on the eyeless tan» pan, an ants carry off eggs and nymphs. An Angolan Reduviid bug, Phoner ates bicolor Stal. sucks the blood of both man and 0. mou_ Bata Z Qellman (I§06B,D,l907B). Austen (l906,l907) reported'3Hthe nomenclature of this bug. The actual specimens involved may still be seen in British Museum (Natural History) collections;7. Ant lions (Neuroptera, Myrmelionidae) have been observed feeding
on nymphs (Ghesquiere 1922). In the laboratory, larvae of clothes moths, Tineola biselliella, are said to feed on eggs and on living
larvae of Q. mou5ata (Volimer 1931).
What was once described as a fungus disease beginning as an opaque white spot at one edge of the body and spreading out to stupify and destroy the tick (Wellman l906A,D,l907B) is now be. lieved by experienced workers to be a normal phenomenon of aging in engorged ticks. Christophers (1906) suggested that this “fun. gus" is actually a white rectal secretion of aged ticks. Burg. dorfer (conversation) is of the opinion that this “white fungus“ is nothing more than crystallized fluid in the malpighian tubules. Often this crystallization produces a complete, hard blockage. The lumen of such tubules fills with white crystals so that nor; mal activity can no longer occur and soon the tick dies. (See Internal Anatomy below).
Numerous factors affecting the ecology of the eyeless tampan are discussed below.
The xeric environment in which 0. moubata is capable of suvival is best explained by two physi3logicaI studies by Lees (l946A, 1947). In his research on water balance in ticks, lees (l946A) found that among the species studied, 0. moubata shows the greatest ability in limiting evaporation from its own Eddy. In this species, the critical temperature at which water loss increases through the superficial waxy epicuticular layer is also high (Iees 1947). This resistance to desiccation at temperatures within its biological range may be correlated broadly with the argasids' choice of dry, dusty ecological niches.
lees summarized his 1946A stuies, in which Ixodes ricinus was the principal species for research and Q. moubata was one of eight other species used for comparative purposes, as follows:
'”The unfed tick gains water from humid air or from water in contact with the cuticle, and loses water by evaporation. Whilst attached to the host the tick is gaining water from the ingested blood and losing water in the excremnt. The engorged tick usually lacks the ability to take up water from humid air.
"The exchange of water takes place mainly through the cuticle. Regulation of the water balance is therefore brought about by the activity of the epidermal cells.
“The cuticle comprises two principal layers, the
'Wdater loss from the unfed tick is not closely related to saturation deficiency, particularly at high
humidities. This departure is due to a physiological cause, namely, to the ability to secrete water. The effects of this activity are such that a state of equilibrium is attained at a relative humidity of about 92%; at lower relative humidities it takes up water. The retention of water at humidities below the point of equilibrium is due not only to the physical properties of the epicuticle but also
to this secretory activity, for water loss increases when the tick is temporarily asphyxiated, poisoned with cyanide, or injured through excessive desiccation. Near the point of equilibrium the loss or gain of water over a wide range of temperature is determined by the relative humidity.
“The uptake of water from humid air occurs when the tick is in a desiccated condition but ceases as the normal water content is restored. After previous exposue to saturated air the adapted tick at first loses water at relative humidities above the point of equilibrium, but later comes to retain water con; pletely.
“Both unfed and engorged ticks possess the abil. ity to prevent or to limit temporarily the entry of water in contact with the cuticle.
'”The engorging female, originally weighing about 2 mg., ingests about 600 mg. of blood. About 300 mg. or two.thirds of the contained water are usually eliminated before the end of engorgement. Evapora_ tion from the cuticle may account for a considerable fraction of this, for the temperature to which the attached tick is exposed (about 37°C.) is, in Ixodes ricinus, above that temperature at which a marked increase in the permeability of the epicuticular lipoid takes place.
“The nine species of ticks examined differ con
siderably in their powers of limiting evaporation. This may reflect specific differences in the nature
of the epicuticular lipoid. The order of their resistance
soni; D. reticulatus; Rhi ice halus sanggineus; Amblyomma
than in Dermacentor andersoni. The more resistant spe.
As already stated, Lees has shown that 0. moubata is more re. sistant to desiccation than most ixodid tick'§. Nymphs exposed to dry (01. 11.11.;-) iir at 25%. survived for 35 days and lost only from one to threewpercent of their original weight daily. This survival period is strikingly longer than that of several ixodid tick spe. cies used in the experiments. After a period of desiccation (five days at 0% R.H.), 0. moubata regains most of its original body weight when placed-‘in $1 R.H. for five days. Water is taken up through the spiracles, for no increase occured when these open. ings were blocked. loss of water occ1n's through the cuticle and spiracles (see Spiracular Morphology and Function below).
In order to carry Lees‘ work one step further, Browning (l954B) conducted a study on the exchangesof water between the atmosphere and 0. moubata. Unfed nymphs were able to abstract water from moist air (95% R.H.) and to restrict their rate of water loss in dry air. This ability was lost (a) in atmospheres containin 30% to 45% C02; (b) in atmospheres containing more than 90,2 N2; (c ixmnediately after the tick fed; and (d) gradually after the tick has been starved for some five nnnths. It was shown that the action of high (3% to 43%) concentrations of C02 is mainly upon the activity of the epi. dermal cells, possibly mediated through the central nervous system. The concentration required to cause opening of the spiracles is only about five percent. These findings are of considerable interest in relation to lees‘ (1947) basic work.
By way of introduction to his 1947 study, lees stated: