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ticks than hairs on them. Heavily infested houses are common elsewhere and are frequently noted in literature from the United States.
The rapid spread of this pest, once introduced to a new
island or major geographical area, is also the subject of numerous reports. Sometimes, however, its paucity and relatively slow pace of spread in apparently favorable areas, as, for instance, Mada... gascar, is noted (Hoogstraal l953E). In the United States, since first reported from Texas and New Mexico (Banks 1908 as R. texanus), §. §. san 'neus has spread widely (Bishopp and Trembly I945, Kohls and Parker i§Z3) through much of the country. It now occurs in some areas where winters are severe but its spread northward ap_ pears to be much slower than in warmer states.
In those parts of the world where definite seasonal changes occur, a spring peak of abundance is comonly observed. During summer and fall, populations, even though great, are not so frequently noticed, probably because they are more scattered in minor peaks of abundance resulting from rapidity or delay with which ticks find hosts. As one example, dogs at Rabat, Morocco, which has seasonal and climatic conditions roughly similar to those of the southern United States, were observed to be very lightly parasitized duin the months of December through Feb» ruary (Gaud and Nain 1935 . In March, the number of ticks began to increase, and in April and May nymphs made their appearance. In May, the count was highest (33 ticks per dog, average), but the infestation rate remained high through August. A sharp decline in numbers was noted in September, followed, inexplicably, by an October rise. Among the 9000 ticks collected, the ratio of males to females was two to one. Zfln order to obtain a more accurate picture of seasonal incidence and abundance in relation to the tick's life cycle, presumably it would be advisable to dis. regard the long-feeding males and count only larvae, nymphs, and females (HH)i7
In Algeria, adults appear suddenly in large numbers on domestic animals at the end of Apil and may be found till August, with the maximum numbers in May. Adults are rare or absent in autumn, winter, and early in spring. Nymphs are found on omestic animals in spring (Sergent and Poncet 1937,1940). This last ob_
servation would appear to indicate that the immature stages over. winter.
In southern and eastern Europe, adults appear on hosts in the middle of April, are most numerous from May to July and by the middle of September again become scarce (Enigk 1947).
In equatorial climes with rainy and dry seasons, ticks are frequently reported as most noticeable at the commencement of the rains and this has been assumed to be an indication that they are then most numerous.
Though two or three generations a year seem likely almost wherever the kennel tick ranges, no definite reports concerning this based on observations in nature are available.
Overwintering of the tick in temperate climes is pobably entirely indoors. For example, MacCreary (1945) states that there is no evidence of overwintering outdoors in Delaware. This tick does not survive long at temperatures under 5°C. (Enigk and Grittner 1953).
In NAMRU3 (Cairo) laboratories, as a piece of research cor. relative with field findings, Dr. Samira El Ziady is undertaking an ecological study of populations from domestic and from wild local stocks, under controlled conditions. Two years will be required to obtain significant data on this subject.
Parasites: The most comonly reported parasite of the kennel tick*1s' the chalcid, Hunterellus hookeri Howard, 1907 (= Ixodiphggui s
*Habrole is sp. fl3halcidoidea, Encyrtidae) has been reported to parasitize immature stages of R.‘§. sanggineus in French West Africa (Risbec 1944). An inquiry concerning t s report, addressed to the United States National Museum, resulted in the following statement
by Dr. B. D. Burks: "This undoubtedly refers to Habrole is cani hila Risbec 1951 Mem. Inst. franc. d'Afr. Noire 13 (pt. I) p. 175. This is Hunterellus hookeri How.; I saw the types in Paris last year. Ferriere Had already (1953) published a note stating that Risbec's species probably was hookeri, just on the basis of the original des.
cription. In 1953, Risbec published a paper transferring his species to Hunterellus, but he still thinks his species can be sep
arated from hooker ......"
caucurtei du Buysson, 1912), a wasp known in many areas of the world. It is specialized for parasitism of ixodids and infests most genera. .A related species, H. theilerae*, has been described by Fiedler (1953) fronzg. oculatus and_H. truncatum in southern Africa. Our knowledge of these parasites will be completely reviewed in a forthcoming volume of this work, but a few preliminary remarks
In Africa, parasitism of the kennel tick by H. hookeri has been occasionally reported. Nigeria (Philip l93IA,B). French West Africa (Blanc, Goiran, and Baltazard 1938. As Habrole is sp.: Risbec 1941.). Uganda (Fiedler 1953, Steyn 195‘5')'—7G&I. go a (Fiedler 1953). Kenya (Philip 1954). We have thus far been un. able to find this wasp in Egypt, where the climate is probably ' too dry for its existence.
Other tick species known to be attacked in Africa are H alomma
(sp. truncatum, according to Theiler, correspondence) and H. leachii in Souih Africa (Cooley 1929 1934); R. e. evertsi in South'Afr1ca (Bedford note in Cooley 1929); species'hot meniioned, from Mozam. bique (Howard 1908); and A. tholloni from the latter area (Santos mas 194%). i"'
R. s. san uineus also is attacked by H. hookeri in Brazil (da Costa Lima I9I5), U.S.A. (Smith and CoIe I9Z3, includes review of previous reports), and other areas of the world.
As summarized by Smith and Cole (1943), infestations of H. hookeri in nature are not known markedly to reduce tick popuIa. iions. Experimental attempts in this direction have been in. effective for tick control even when millions of parasites were released (Cooley and Kohls 1933) to attack the Rocky Mountain spotted fever vector, Dermacentor andersoni (Stiles). Soviet experiences with this parasite have been reviewed by Pervomaisky (1947) and Blagoveschensky (1948).
*Dr. B. D. Burks states (correspondence) that this unquestionably is a distinct and valid species.
Larvae of H. hookeri feed on all contents of engorged nymphal ticks and pupate in the Body of the host. Adult wasps emerge from the nymph by gnawing a hole through the host's expanded integument. Mating occurs soon afterenergence. Oviposition, by insertion of the ovipositor through the tick's integument, may follow immediate... ly after mating. Unfed nymphs are preferred for egg laying, though oviposition in engorged nymphs also occurs. Eggs are sometimes laid in tick larvae; in these, however, the parasite undergoes a. latent period until after the larval_nymphal molt. Latency con. tinues in unfed, hibernating ticks until they commence engorging. [ Cooley and Kohls l928,l93L._7
Brumpt (19303), who experimented with rearing this parasite in _s. sanruineus, noted that a period of some 83 days passes before nymphs exhibit signs of parasitism, a factor of practical interest in transportation of the wasps to new areas or laboratories.
Adult wasps may sometimes be noticed running rapidly on the dog's hair in search of ticks (da Costa Lima 1915, Philip l931.A,B).
Morphological characters of tick..parasitizing wasps have been compared by Steyn (1955) who concludes that H. theilerae might be expected to be of greater value in biologicfi control than the other species. (If, however, H. theilerae is actually as infrequent in nature as present scanty recofis suggest, its range of physiological adaptability may negate this possibility _ HH .
Predators: In a Corsican house invaded by both kennel ticks and Theridiid spiders, Teutena trian osa Wick., the spiders were observed feeding on the ticks au et ). Under experimental conditions, they fed on both the immature and adult stages and young spiders attacked ticks shortly after hatching. Although the predators also fed on flies, they showed a preference for ticks. Under August, midsummer conditions, the spider life cycle from egg to adult required three weeks. Six to twelve eggs were laid in each webbed mass, and females produced from eight to ten of these balls.
In Russia, a staphylinid beetle, Juracekia asphaltina, devours Rhi icephalus ticks (IE. sansuineus) in nests of the ground squirrel, Sitellus pygmaeus (Flegontova I938).
MAN: E. 3. san 'neus, in some areas, is considered to be the principal(vector of Egutonneuse fever (tick_bite fever), Rickettsia conorii see however a e 687 . It is kn wn to transmit the rickettsia cadsing the,cloiely related "Indign tick typhus“. It is a vector of Rocky Mountain spotted fever (2. rickettsii) in the warmer parts of the Americas. It is said to Be the vector of a virus causing mCongolese red fever", a syndrome of moot identity and etiology.
Persons bitten by this tick sometimes complain of pruritus, due possibly to injection of a toxin while feeding.
A number of the pathogens listed under experimental relations below may be transmitted in nature but the details have not yet been elucidated.
DOGS: R. s. san=uineus transmits two diseases to dogs, the highly fatalfcahine rickettsiosis, caused by Rickettsia canis, and canine piroplasmosis, or malignant jaundice, caused By Eabesia canis. In addition, it is an intermediate host of He tozoon canis which results in an anemia and infection when dogs sw§Ilow tick . Tick typhus or boutonneuse fever, Rickettsia conorii, is apparently transmitted amng dogs and from dogs to man By the kennel tick. It seems likely that this arthropod transmits Salmonella enteritidis, which causes a paratyphoid disease in dogs and in la55ratory animals. when dogs are heavily infested, loss of blood and nervous energy from irritation may be severe.
See also experimental relations below.
Other domestic animals: Spirochetosis of sheep, goats, horses, and cattle, caused by Borrelia theileri, is transmitted by the brown dog tick in some areas.