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an olensis, and the duskyafaced warbler, Trichclais scoto . It Is difficult to determine whether so many kinds of excep onal hosts are the result of wider and more extensive field search or of ecological differences (see BIOOGY below).

Laborato hosts: Lewis (193211) observed that although nymphs and Edélts fed readily on hares, larvae were more reluctant to do so. From this Lewis concluded that hares are less prefered hosts of larvae than they are of other stages, an inference that probably should be modified by other biological considerations.

At Onderstepoort, both larvae and nymphs feed readily on guinea. pigs (Theiler, correspondence).

stionable remarks and conclusions: Lewis (1932A), after exami ng o s' specimeH§_from rodent burrows, concluded that larvae feed less readily on rodents than do nymphs. Supporting data were not provided but, unless we are still unaware of some unique phase in the life cycle of this tick, it appears that in East Africa, at least, larvae and nymphs attack the same host. Data from collections made throughout the entire year will be necessary before other conclusions can be drawn.

Lewis (l932A) noted a number of larger mammals, from the size of porcupines to rhinoceros, as nmphal hosts, and Stella (19393) indicated guineafowl. Reidentification of pertinent material is indicated. The Onderstepoort collection (Theiler, correspondence) contains a single collection of nymphs from a red hartebeest in Natal.

Lounsbury (19045) "wholly failed in attempts to rear larvae on dogs, not one of man thousands applied having fed to reple; tion", but later (19060 succeeded in doing so. The ox was considered an unsuitable host for larvae but "nymphs and adults do not appear to dislike cattle".

Around Lourenco Marques, Sant'Anna (1911) noted, larvae of R. s. simus are encountered and so is a human disease, possibly

that now called boutonneuse fever, following tick bites. Sub. sequent reviewers have elaborated this remark to indicate that

larval simus bite man, and the more enthusiastic have quoted this report as stating that the larvae transmit boutonneuse

fever.

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Laboratory studies indicate that E. 3. simus undergoes a three. host type of life cycle.

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Under experimental conditions, Theiler (unpublished), Lewis

(l932A), and Lounsbury (1905) have found the life cycle periods to be as follows:

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PERIOD DAYS °C. TEMPERATURE
Theiler Lewis Lounsbggy Lewis
Oviposition to hatching 20.24 31 21-27
Larval prefeeding period 3 7
Larva feeds 2. 5 3 2
Premolting period 8.12 11 6 23.26
Nymphal prefeeding period 14 7
Nymph feeds 3.11 5 3
Prennlting period l3_2l* 27 14 21.25
Adult prefeeding period 7 7
Female feeds 7-24 7 9
Preoviposition period 3- 6 6 23-26
80.125 111

Note: Theiler rearings at 24°C. to 26°C. and approximately 8Q% R.H.

Hares were used as hosts for all stages in Lewis‘ experiments, though not with great success. The ease with which these observations could be repeated using normal hosts and normal conditions of temperature and humidity found in rodent burrows suggests an interesting study for collecting comparative data.

Field observations indicate that both immature stages feed on nest.inhabiting rodents. The nymphal_adult molt occurs in the same nest, and adults remain in the nest for some time before seeking larger hosts. As discussed below, a considerable amount

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*2 months in winter.

of additional field study is required to answer many questions concerning the life cycle of R. s. simus. This tick and H. leachii are the only ubiquitous African species that in their immature and adult stages, respectively, feed first on nest. inhabiting rodents and then on larger animals. More rigid field observations, besides being a most pleasurable occupa. tion, should be easily accomplished.

In the following paragraph the question of where the female oviposits is raised. In this connection, Howard's (19098) ob. servation of an unengorged male and female of R. simus (- R. ecinctus) mating on the leaf of an Acacia thorn tree on th§ Zambgsi River is of special interest-(although the possibility of misidentification of these specimens must be considered). Almost invariably, rhipicephalid ticks mate on the host, as do most other ixodids. Howard's note indicates the necessity of further research to determine whether R. s. simus possesses a unique type of mating and egg laying, a§d,_if so, whether this is a constant or an exceptional phenomenon, and whether it is associated with an ability of larvae to seek out their pre. ferred habitat and hosts rather than waiting for a passing r°dQnt 0

Mating observed by J. B. Walker (correspondence) in Kenya has been of the ordinary rhipicephalid type, on the host. Walker also says that engorged females that have already dropped from the host will mate with males that have been feeding on the same host and then removed and placed with these females. This might be merely a mating act and not initial or essential fertiliza. tion (HR), for generally, it appears, female engorgement is not complete or normal unless copulation has been effected.

Ebology

From Roberts‘ (1935) studies in the Nairobi area it appears that the immature stages of R. s. simus prefer slightly subsurface rodent nests rather than deeper'ne§t§-Bf the same and of other kinds of rodents. The grass rat, Arvicanthis, is possibly the most important immature stage host. It is not known whether larvae actually seek out the nest and attack the animal there, or whether they attach to a rodent wandering in search of food and are then carried to any nest that their host might be in.

habiting. It would be contrary to all previous observations on ixodids to assume that the female selects the situation in which she oviposits, although this possibility must be investigated.

By way of comparison, imature stages of Q. leachii in the Nairobi area prefer deeper nests of Mastomys couc a. n the Njoro area of Kenya and in the Sudan, owever, we have taken

larvae and nymphs of these two ticks species in both shallow and deeper nests.

Arvicanthis nests are usually within a foot of the surface of the ground, But sometimes they are two or three times as deep. The nest is reached by a network of a few or many tunnels, each with a small exit among vegetation. The round nests, composed of lesser or greater amounts of moist grass and leaves, appear to be occupied for several generations. Slight rises, such as borrow heaps, mounds beneath bushes, or pathsides are favorite burrowing sites. These rodents frequently nest and search for food in close association with human activities.

Habitats of some of the chief South African hosts of inn mature stages (see HOSTS above) differ widely. Aetho. s nemauensis frequents rock crevices and piles of stones wE¥1e A. cgzgsoihilus is more terrestrial and lives in sheltered bush on e p ains, among rocks, or in burrows under bushes or rocks. Otogys lives in holes in the ground or in selfmade shelters in mat e vegetation; those in the Karroo construct these shelters from large piles of weeds while others utilize small grass or weed nests in marshes or among rocks. Rhabdo s hides in holes in the ground and its pathways run through dense vegetation.

It is evident, therefore, that the usual ecological niches of

hosts of immature stages in East Africa differ from those in southern Africa.

In southern Africa, Theiler (unpublished) finds that the glossy tick occurs from the eastern tall grass veld (Port Eliza. beth) northwards through subtropical overgreen and deciduous tree and thorn forest into northern Transvaal, Southern Rhodesia, and Mozambique. In these subtropical stretches, the heavy rainfall areas of Natal are comparable with the coastal plains of Kenya, and the dry, warm conditions in Kruger National Park and northern Transvaal are comparable with central Kenya (see next paragraph). Records indicate this tick to be less common west

of the Drakensberg escarpment, but to occur up to 10,000 feet elevation in Basutoland. It is common in Highveld with good arunial rains, heavy frost, and snow in winter but seldom recorded from dry Highveld. In the mixed grass veld of the middleveld, with ten to 25 inches of rainfall annually and cold, sharp winter frosts, it is almost entirely absent, though it does occur in southern Transvaal middleveld. It is nuerous in the Bankenveld and Limpopo highlands and also in Bushveld regions of Transvaal. In Karroo areas it dies out in areas with less than ten inches

of rainfall annually. Records from Southwest Africa are only from the northern, more moist areas. In Southern Rhodesia, it

is especially common in eastern and northern areas.

In the hot, more or less humid, coastal lowlands of Kenya, R. s. simus is especially common (Wiley 1953). Dick and Lewis Tl9Z7) consider this to be the most abundant and widely distri_ buted tick in the Kenya coastal lowlands and Wilson (1953) also notes its frequency there in areas where H. ravus and A. gema are found (cf. pages 681 and 274). In the arid N '

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orthern Prov. ince of Kenya, the glossy tick is less common than elsewhere in the Colony, but it does occur anywhere under a variety of condi_ tions, whether these be hot and arid, cold damp high altitudes, or hot, moist coastal lowlands (Wiley 1953). Theiler (19438), supported by subsequent remarks by Santos Dias, noted that R.

s. simus is not only particularly abundant but actually theEbst ubiquitous tick in some parts of Mozambique.

Study of data for the Somalilands, in the coastal areas just north of Kenya, suggests that R. s. simus is common only under local conditions in these less humid areas. From details published by all investigators concerning the Belgian Congo it would appear that in most parts of the colony this tick is decidedly less common than it is in southern Sudan.

In the Sudan, R. s. simus is common everywhere in the south and at least frequéht in southcentral areas. It becomes more localized and uncommon with the approach of semidesert conditions. Many areas in which it occurs have a long, severe dry season but rainfall of twenty to almost fifty inches annually during the wet season. King (1926) noted that although this tick is absent in the desert areas of Northern Province, populations had estab_ lished themselves there when local conditions of humidity were modified after pump and basin irrigation was introduced.

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