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White bearded gnu (Loveridge 1928). Dik-dik (Loveridge 1928, Stella 1939B). Kobus ellipsiprymus and Adenota vardoni (Schwetz and Collart 1929). Hippotragus niger roosevelti (Santos Dias 1952D). Hartebeest and lechwe (Matthysse 1954).

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 were in no instance affected by these ticks.

Buffalo: (Howard 1908, Richardson 1930, Lewis 1931C,1943, Walker 1932, Jack 1942, Santos Dias 1950B,1952D).

Carnivores: Hunting dog (Lycaon sp.) (Howard 1908). Lion (Zumpt 19428, Santos Dias 1953H, Matthysse 1954). Felis capensis hindei (Allen and Loveridge 1933). Jackal (Santos Dias 1952D, 1953B). Leopard (Santos Dias 1952H,1953B, Matthysse 1954).

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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 (Theiler, unpublished).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). (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 chrysopygus and Petrodromus s. sultani) and Peter's gazelle (Lumsden 1955). 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. Varia tion 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 condi tions of high humidity, from 110 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 61 to 146 days depending on the season. Nuttall (1913B), working in an English laboratory, reared this species in a minimum of 115 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, nymphal, 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 nymph, four to six days at 30°C., or 21 to 41 days at 15°C. to 17°C., 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 14°C. Away from the host, therefore, tem perature 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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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, 110 to 129 days are necessary to produce adults of the F1 generation in Nyasaland (Wilson 1944,1946,1950B).

The life cycle in Northern Rhodesia is much like that of A. variegatum (Matthysse 1954), although adult brown ear_ticks arē more severely restricted to the wet season. No adults appear until November, when they reach a high peak of abundance, but their num bers 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 Sep tember'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 1oC. to 4°C. for eight or nine days. Many of the re sulting 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 (19398), working in Kenya, has recorded the

longest survival time for unfed stages of R. appendiculatus: larvae about nine and a half months, nymphs about twenty months, and adults about two and a half years. In South Africa, du Toit (1928B) noted the same survival time for adults in the laboratory and also that unfed adults remained in the field for fourteen months. Nuttall (1913B) was able to keep unfed larvae alive for eleven months (slightly longer than Lewis' observations) but survival periods for other stages were shorter than those of Lewis. Wilson (1946) could not maintain unfed larvae in his Nyasaland laboratory for more than a week or so.

Ecology

As many as 1000 individuals of this species may be found on single host, most commonly on the ear, on the inner, concave, surface and especially along the anterior margin. When the infestation is heavy, fewer numbers also attack around the base of the horns, eyelids, cheek, neck, tail switch, udders, scrotum, vulva, anus, and flanks (Wilson 19483,1949, Beakbane and Wilde 1949). Immature stages are mostly on the ears but not deep in them, as is true of immature R. evertsi. Immature B. decoloratus are frequently associated with R. appendiculatus along the edge of the ear. If the host is heavily infested, immature brown ear_ ticks may be found on many parts of the animal's head. Unengorged larvae and nymphs are so small that they are difficult to detect on the host (Wilson 1948C).

Heavy infestations of brown ear-ticks and of nymphs of R. evertsi on and in the ears of cattle frequently leads to a severe bacterial otitis, caused by Corynebacterium pyogenes, and sloughing of the external ear (Clifford 1954). Dr. J. I. Taylor, recently Director of the Uganda Veterinary Service, states (conversation) that the tympanic membrane is frequently ruptured by heavy infesta tions and a severe lymphangitis occurs in the head and neck regions.

In order to assess the degree of infestation of cattle in the Lela district of Kenya, an area with about 58 inches of well distributed annual rainfall and with a high average temperature and humidity, the East African Veterinary Research Organization (Binns 1951) removed a single animal out of each local herd at fortnightly intervals and collected the ticks from its ears.

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