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HOSTS*

Most prominently listed as hosts of all stages of R. appendiculatus by most authors are cattle, but domestic goats, sheep, horses, mules, donkeys, and dogs are also commonly listed. The comparative incidence on these animals has seldom been carefully observed. The brown ear-tick appears to feed more readily on cattle than it does on sheep, according to Worsley (1950). A single male has been reported from a domestic chicken (Lucas 1954).

Wild antelopes and buffalo are frequently reported, and numerous other animals are infested on occasion. Wild carnivores appear to be parasitized only rarely.

Larvae and sometimes nymphs feed on medium-small animals such as hares and cane rats, and may also attack man. Mostly, however, they are known from the same larger size hosts as adults. The question of why some larvae and nymphs choose smaller hosts deserves further investigation.

In connection with the account of noninfestation of young antelopes (below), it is of interest that Binns (1951) has reported that calves tied to trees in the Lela District of Kenya were attacked within two days after birth. Although these calves harbored only one or two ticks during the first week, four to ten ticks infested them after a fortnight. At the end of the month, over twenty brown ear-ticks were feeding on some calves. Afterwards, the count fluctuated considerably but averaged weekly lz.9 adult ticks per animal for six calves for three months. This was a lower average than for freely grazing older animals (but "adequate to provide a reasonable exposure to East Coast fever").

Adult Hosts (only wild animals listed)

Antelopes: Death of waterbuck due to heavy infestation (Hutchins 1917). # of the following antelope hosts have been reported by several authors. Uganda kob (Warburton 1913). Nyala, kudu (Bedford 1932B, Santos Dias 1952D). Impala (Bedford 1932B. Santos Dias 1952D. Meeser 1952). Bushbuck, waterbuck (Bedford 1932B). Sable antelope, Livingstone's suni, steenbuck, klipspringer (Jack 1942).

*The matter of domestic animal hosts will be treated in the forthcoming volume on disease relations of African ticks. Numerous additional host records are provided in the APPENDIX.

White-bearded gnu (Loveridge 1928). Dik-dik (Loveridge 1928, Stella 1939B). Kobus ellipsiprymus and Adenota vardoni (Schwetz and Collart 1929). Hi tr s niger roosevelti (Santos Dias £ #######

Mettam (1933) reported the interesting observation that newly-born kob, duiker, bushbuck, and reedbuck in an Entebbe

paddock heavily infested with R. appendiculatus and R. evertsi these ticks.

were in no instance affected by

Buffalo: (Howard 1908, Richardson 1930, Lewis 1931C,1943, Walker I:32, Jack 1942, Santos Dias 1950B,1952D).

Carnivores: Hunting dog (Lycaon sp.) (Howard 1908). Lion (Zumpt. 19.2B, Santos Dias 1953H, hysse 1954). Felis capensis hindei (Allen and Loveridge 1933). Jackal (Santos Días # . Leopard (Santos Dias 1952H, 1953B, Matthysse 1954).

Man: (Howard 1908).

Miscellaneous: "All game animals in Kenya" (Lewis 1939A) but "rare on game in Masai Reserve" (Lewis 1934). Warthog and elephant (Zumpt 1942B). Zebra (Lewis 1931,1932, Santos Dias 1952D, Matthysse 1954). Giraffe (Santos Dias 1953B).

Stage of Tick Questionable

Squirrel (Bedford 1932B). Hares (Schwetz 1927A, Jack 1942).

Nymphal Hosts

Hares and rock rabbits (Pronolagus sp.) (Theiler, unpublished). Large cane rat (Wilson 1950B). Bush squirrel (Santos Dias 1952D). Duiker (Lewis 1931C). Zebra, hartebeest, lechwe, kudu, hares (large numbers), and jackals (Matthysse 1954). Man (Equatoria Province record above. Pijper and Dau 1934). "

Tick identification "probable": elephant-shrews (Rhinonax # and Petrodromus S. sultani) and Peter's gazelle Lumsden I'55). "Parasitism of elephant shrews by nymphs of this

species is probably rare or questionable.

Larval Hosts

Hares (Lewis 1934). Man (Pijper and Dau 1934). See APPENDIX.

BIOLOGY

R. appendiculatus is a three host tick. In Nyasaland, where there is a single rainy season each year, the brown ear-tick produces one generation a year (Wilson 1946, 1950B) but in South Africa it may produce one or two generations a year (Lounsbury 1904). In Kenya and Uganda, where two rainy seasons occur each year, multiplication is faster and two or three generations breed within a twelve months' period (Wilson 1953). As stated in the section on HOSTS above, adults feed on large animals, nymphs attack large or medium size hosts, and larvae appear to prefer small to medium size animals above the size of usual rodents. Variation in size and structure of this species, as influenced by hosts and environment, are discussed under REMARKS below.

Life Cycle

In Nyasaland, Wilson (1950B) found that under optimum conditions of high humidity, from ll.0 to 129 days are necessary to complete the life cycle. In South Africa, Lounsbury reared the brown ear-tick through its life cycle in from 6l to ll:6 days depending on the season. Nuttall (1913B), working in an English laboratory, reared this species in a minimum of ll:5 days, from preoviposition to preoviposition period, when maintained at between 17°C. and 20°C.

Nuttall (1913B) summarized his life cycle studies about as follows: R. appendiculatus requires three hosts upon which to feed in its larval, nymphaI, and adult stages. Larvae usually remain on the host for from three days to a week; when they remain considerably longer they either do not imbibe blood freely or they may not actually attach on the day on which placed on the host. Engorged larvae drop off up to fifteen days after having been placed on the host. Nymphs remain on the host for five to eleven days. Fertilized, replete females abandon the host after six to fourteen days. Males attach to the animal for longer periods, and unfertilized females may remain on the host up to 24 days.

The temperature at which the host is maintained, within the limits observed, exerts no apparent influence on the time that different stages remain attached. Postfeeding metamorphosis requires the following time: from egg to larva, 32 to 65 days at 17°C. to 19°C.; from larva to n ### to six days at 30°C., or 21 to 41 days at 15°C. to 170C., or 60 to 75 days at 13°C. to 14°C.; from nymph to adult, ten days at 37°C., or 21 to 38 days at 20°C., or 64 days at L.P.C. Away from the host, therefore, temperature markedly influences the rate of development.

Once the female abandons the host, oviposition commences after six to 23 days at 17°C. to 19°C., or after fifty to sixty days at 12°C. Oviposition continues for from fifteen to 56 days, during which period the female lays from 3000 to 5770 eggs.

Nuttall's average minimum times and Theiler's minimum and maximum times for various periods of the life cycle are summarized as follows:

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Larval prefeeding period 7 -
Larva feeds 3 3-7
Premolting period 21 (179C.) 10-49
Nymphal prefeeding period 7 -
Nymph feeds 5 3.7
Premolting period 21 (20°C.) 10-6l
Adult prefeeding period 7 -
Female feeds 6 4-10
Total 115 63-202

Field observation indicates the extreme importance of knowing not only the temperature but also relative humidity at which all rearing experiments such as these are accomplished.

*Eggs require three months for hatching in wintertime, South Africa. Life cycle figures published by Wilson (1950B) for Nyasaland fall well within the above limits. Lewis (1939B) in Kenya found that larvae and nymphs remain on their host for several days longer than the above periods.

Females in Nyasaland engorge and oviposit only during the wet season when the relative humidity is above 75%. Adults, especially engorged females, are rare at other times of the year. Unengorged larvae die in large numbers during the cool, dry months of the year, but nymphs are common at this season. Under optimum conditions of high humidity, ll.0 to 129 days are necessary to produce adults of the Fl generation in Nyasaland (Wilson 1944, 1946, 1950B).

The life cycle in Northern Rhodesia is much like that of A. wariegatum (Matthysse 1954), although adult brown ear-ticks are more severely restricted to the wet season. No adults appear until November, when they reach a high peak of abundance, but their numbers drop rapidly in the dry season, late March and early April, and until October adults are rare. In some areas, however, a few adults persist through the dry season. Larvae are not found until late in the rainy season, late February, and are abundant from March through August. Larval and nymphal incidence overlaps from early April through August, but nymphs rapidly disappear with September's hot weather and are completely absent by early November. Incidentally, adults of R. compositus (= R. ayeri) preceed those of R. appendiculatus, being abundant in September and October and present in some numbers in July, August, and November. This may have some significance in maintaining and transmitting East Coast fever in cattle when adult brown ear-ticks are absent.

In laboratory studies on the effect of artificial climates (Mulligan 1938), engorged females proceeded to oviposit when returned to a temperature of 24°C. to 27°C. after having been exposed to 19C. to 4°C. for eight or nine days. Many of the resulting eggs shriveled and died; some larvae that hatched did survive but many others succumbed. Eggs hatched after having been exposed to the same low temperature range for six hours. About half of the engorged larvae subjected to the low temperature failed to molt and died.

The survival of ticks, whether fed or unfed, is of practical importance. Lewis (1939B), working in Kenya, has recorded the

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