« PreviousContinue »
Recently, Davis and Mavros (1956B) have been most successful in rearing larvae on guinea pigs and nymphs and adults on white mice. Between feedings, ticks were held at 30°c. in a humidified cabinet, The life cycle under these conditions required from four to eight months. Larvae fed from six to fifteen days, most ly for eleven to thirteen days, and molted to nymphs ten to twelve days later. This lot all reached the adult stage after three nymphal molts, as follows: first to second instar, fourteen to twenty days; second to third instar, seventeen to 32 days; third instar to adults, 21 to 37 days. One third nymphal instar specimen fed twice before molting to an adult male. This individ ual required 140 days postlarval feeding to reach adulthood while the most rapid time for this interval, also for a male, was ninety days.
In an additional lot, six males and fourteen females required three nymphal instars and two females underwent a fourth nymphal molt. Three pairs fed twice in the last nymphal instar. The last nymphal instar lasted from 26 to 65 days, but most required only 26 to 33 days. Females fed for eight to 21 minutes and mated for ten to 27 minutes. Oviposition commenced eight to 58 days after feeding and larvae hatched after eight to 24 days. The number of eggs per batch ranged from 24 to 96, and while generally smaller batches showed a higher rate of fertility than larger batches this was by no means consistant. For instance, in one batch of 24 eggs 22 larvae hatched, one batch of R2 was entirely fertile, a batch of 62 was about fifty percent fertile, and the batch of 96 eggs hatched 8l larvae. The least fertile female oviposited a second time without a second feeding or mating. The most fertile fem male fed a second time and then oviposited though without having mated since the first feeding three months previously.
Further observations showed that while larvae take a small amount of blood within an hour of attaching to the host, the bulk of the blood is ingested shortly before completing feeding. Molt ing ticks free themselves from the exuvia within a few minutes after the skin splits. Mating and feeding takes place readily in daylight. Feeding adults stand perpendicularly, bracing themselves against the tube; when partially distended they fall over on their dor sum to complete engorgement.
A. brumpti lives in areas of low rainfall (Ovamboland, Kala hari, Nuba Mountains, Egypt) or in dry niches within areas of comparatively high rainfall (Kenya, southern Sudan, Transvaal). It rests in caves, lairs, or dens, where it feeds on either permanent mammal residents or on visiting mammals or lizards, or it may hide under rocks from whence it emerges to feed on passing lizards or mammals.
The original Ethiopian specimens were found in dust under rock ledges in a dry streambed visited by porcupines (Nuttall et al 1908. Brumpt's Precis). It was said that these adults wandered about at night but not during the day. King (1915) found specimens in caves and crevices where they were living among debris of soil and rotting leaves and twigs. One of Bedford's (1936) individuals was hiding under a stone. In Southeastern Egypt we have found from one to 23 nymphs and adults together a millimeter or two below the surface of fine, dry sand in small caves and in holes in rocky hillsides. These areas range from barren desert bordering wadis with a little vegetation to arid parkland at the base of mountains facing the Red Sea.
In the lowlying country north of Kitui, Kenya, Heisch (1954F) observed immobile specimens on fine, brown earth under large boul. ders on a peneplane of red, sandy soil covered by thornbush.
Dr. Heisch has informed me (conversation) that the loose soil below these rocks is probably too sparse for burrowing by the ticks. He and Dr. Garnham, who accompanied him on a collecting trip to this area, have also told me that the ticks rest in rock crevices or between rock layers where there is little or no accumulation of soil. It is of interest to learn from information furnished Cun liffe (1914B) for other parts of East Africa that Brumpt's argas burrows in the dust of termite mounds where large game animals roll.
Biologically, therefore, in its feeding and resting habits, A. brumpti appears to show tendencies towards certain intermediate characters between typical Argas ticks and typical Ornithodoros ticks. Argas ticks in all stages are considered typically as fairly host specific parasites of birds or of bats and as ticks that nor
mally hide in crevices but do not burrow in sand or soil. Orni. thodoros ticks, on the other hand, usually parasitize mammals, although exceptions are known, and unless the soil is too hard, they normally burrow below the surface or at least hide in cracks in soil. It is, therefore, of interest that larval A, brumpti feed, apparently more or less indiscriminately, on reptiles, birds, and mammals, and that nymphs and adults attack either liz. ards or mammals. A further interesting observation, from both Dr. G. E. Davis' and our laboratories, is that the various stages of this tick feed fully on white mice, whereas most other Argas species feed only partially on mice. When resting, A. brumoti apparently prefers to burrow in soil or sand, but if this is not possible it hides among surface debris or between or under rocks,
King (1926) mentioned the possibility that Brumpt's argas might infest human dwellings although actual records had not been obtained. Archibald (1923) reported Brumpt's argas among a col lection from in and around human dwellings, but he did not specify exactly in which situation specimens were taken. Archibald's records and specimens cannot now be located. Walton (1950B) states that in Kenya this species does not occur in human huts.
MAN: Bites of A. brumpti may be quite painful to human beings and cause itching lasting for years. Kenya natives claim that this tick causes pain and sickness when it bites man.
LIZARDS: In Kenya and in Egypt, A. brumpti and lizards have been found infested with a hemogregarine, Hepatozoon argantis Garnham, 1954.
HYRAXES: This tick should be considered as a potential vector of the piroplasm Echinozoon hoogstraali Garnham, 1951, a parasite of Heterohyrax brucei hoogstraali.
The diagnostic characters listed below comprise the criteria for Pospelove Shtrom's (1946) genus Ogadenus, herein considered as a subgenus of Argas. Warburton's (1933) views on the generic position of A. brumptl will be reviewed in subsequent studies of
Schulze (1936G) compared the body outline of A. brumpti with that of certain fossil trilobites that it happens to resemble.
Neumann's original adult specimens from Ethiopia measured from 15 mm. to 20 mm. long and from 10 mm. to 13 mm. wide. The size range among available Sudan and Egyptian females is from 10 mm. to 12 mm. long and from 7 mm. to 8 mm. wide. The dorsal integument is marked most distinctively by large, symmetrical polygonal de pressed areas bounded by rugose ridges; laterally the dorsal integument is evenly striated. A continuous, clear, and distinct sutural line divides the dorsal and ventral sur. faces. Discs, which are small and inapparent, lie in clumps or lines in the integumental depressions, and short hairs are scat tered anteriorly and posteriorly on the periphery of the body. The outline of the body is subquadrangular with parallel lateral margins, a bluntly rounded posterior margin, and a pointed projection of the anterior margin over the mouthparts. Tarsus I has two dorsal humps and the other tarsi each have a prominent sub apical dorsal protuberance. Males have a narrow, rounded genital aperture; females have a transversally elongate, narrow genital orifice.
The nymph closely resembles the adult, except for size and absence of genital aperture. The larva has been described by Cumliffe (1914B) and by Hoogstraal and Kaiser (1956).