Spilopsyllus Cuniculi Research Articles

Effect of Age, Sex, and Hormone Treatment of the Mouse on the Level of Infestation by Rhipicephalus sanguineus Larvae

Immature and mature laboratory mice of both sexes were exposed to Rhipicephalus sanguineus larvae. The former were significantly more susceptible than mature mice. Male mice in both age-groups and immature females became infested with significantly more R. sanguineus larvae when treated with cortisone than did control mice. Mature male mice treated with cortisone became as susceptible to infestation as untreated immature mice, but the naturally more resistant mature female mouse became even more resistant upon cortisone treatment. Estrogen-treated male mice became more resistant than controls in both age-groups. It appears that female mice are more resistant to infestation because of some factor associated with the female hormone level. Almost all helminthic and protozoan infections which have been examined experimentally become enhanced upon cortisone treatment of the host. This has been attributed to an anti-inflammatory effect and a lowering of the host's resistance rather than modification of the parasites themselves. Work on ectoparasites appears to be confined to the sheep ked, Melophagus ovinus, and the rabbit flea, Spilopsyllus cuniculi. The observations of Nelson (1962), Nelson and Bainborough (1963), and Rothschild and Ford (1964) on these insects demonstrate that modification of the host with cortisone also increases the susceptibility of the host. Among ectoparasites the significance of the age of the host in its susceptibility appears to have been noted only in a few cases. Buxton (1948) observed that Xenopsylla cheopis that fed on very young mice laid fewer eggs than those fed on adult mice. Rothschild and Ford (1964), in their work on Spilopsyllus cuniculi, noted that 2to 6-week-old rabbits were unattractive to these fleas, while very young rabbits (5 or 6 days old) and does during the last 10 days of pregnancy were the most attractive. In Minnesota, Cook and Beer (1958) noted in wild populations of meadow voles, Microtus pennsylvanicus, that old males harbored more lice (Hoplopleura acanthopus) than young male animals. This was not true in female Received for publication 16 August 1965. *Present address: Department of Parasitology, The College of Veterinary Medicine, University of Baghdad, Iraq. meadow voles or in deer mice (Peromyscus maniculatus bairdii) infested with H. hesperomydis. This infectibility of a host with certain ectoparasites appears to be related to its age, but in different ways in different host-parasite relationships. The sex of the host and its effect on different ectoparasitic infections has received some attention. Cook and Beer (1958) found sigificantly more male than female Microtus pennsylvanicus infested with the louse Hoplopleura acanthopus, but no difference attributable to sex was observed in the case of H. hesperomydis on deer mice. Rothschild (1964) states that bird fleas of the family Ceratophyllidae and various fleas on small mammals are generally more numerous on male than on female hosts. The human flea, Pulex irritans, however, according to the same author, shows a predilection for women; and bat fleas in the genus Ischnopsyllus move onto female bats before the bats migrate to their summer colonies. Among the acarines, only Nutting (1964) appears to have noted differences related to the sex of the host. Demodex spp. infested more males than females in the hamster, Mesocricetus auratus, while the reverse was true in the rabbit, Sylvilagus transitionalis, and bat, Myotis lucifugus. The experimental use of sex hormones and surgical procedures in the host, although widely used for internal parasites, have not been applied for ectoparasites. The purpose of the present study was to assess experimentally the effect of age, sex, estrogen, and cortisone in the laboratory mouse

Observations on gravid rabbit fleas (Spilopsyllus cuniculi (Dale)) parasitising the hare (Lepus europaeus Pallas), together with further speculations concerning the course of myxomatosis at Ashton, Northants.

Observations on gravid rabbit fleas (<i>Spilopsyllus cuniculi</i> (Dale)) parasitising the hare (<i>Lepus europaeus</i> Pallas), together with further speculations concerning the course of myxomatosis at Ashton, Northants.

Myxomatosis and the rabbit flea.

Myxomatosis and the rabbit flea.

Myxomatosis and the rabbit flea.

Myxomatosis and the rabbit flea.

Another specimen of Opisocrostis bruneri (Baker) with two spermathecae (Siphonaptera).

Holland (1943) recorded 2 spermathecae in a specimen of OPISOCROSTIS BRUNERI from Canada. Two spermathecae in other fleas normally having one have been reported for Stenoponia americana (Baker) by Ewing & Fox (1943), Neopsylla setosa Wagner by Wagner & Ioff (quoted by Smit, 1949a), Nosopsyllus fasciatus Bosc by Smit (1949a), Opisocrostis t. tuberculatus (Baker) and Monopsyllus vison (Baker) by Holland (1949), Spilopsyllus cuniculi (Dale) by Mead-Briggs (1964), and Xenopsylla cheopis (Rothschild) by Smit (1949b) and Sharma & Joshi (1961).

MATURATION AND EGG-LAYING OF THE RABBIT FLEA (SPILOPSYLLUS CUNICULI DALE) INDUCED BY THE EXTERNAL APPLICATION OF HYDROCORTISONE.

IN a previous communication1 it was shown that maturation of the female rabbit flea could be induced by injecting castrated buck or virgin doe rabbits with a commercial preparation of the anterior lobe of the pituitary gland (‘Ambinon B’ Organon Laboratories, London). In Nature the rabbit flea can only mature its ovaries feeding on a doe during the last 10 days of pregnancy, or on new-born baby rabbits during the first 5 or 6 days of life.

The Reproductive Biology of the Rabbit Flea Spilopsyllus Cuniculi (Dale) and the Dependence of this Species Upon the Breeding of Its Host

ABSTRACT Unlike any other species of flea which has been cultured successfully Spilopsyllus cuniculi (Dale) is entirely dependent for its own reproduction upon its host becoming pregnant. The ovaries of fleas kept on male or non-pregnant female rabbits remain immature whereas those on a pregnant host are mature at the time of parturition. Vitellogenesis commences at a critical point approximately 7 days pre-partum, irrespective of how long the fleas have been on the host. It is postulated that a factor required by the flea for ovarian development is only available during the final week of pregnancy, and not at all in male or non-pregnant rabbits. The factor disappears from the adult after parturition but is present in her nestlings for at least 7 days. Most fleas desert the adult doe shortly after the young are born and enter her nest, where copulation and oviposition occur. The factor does not act solely as a trigger initiating in the flea developmental processes which then continue in its absence; ovarian regression occurs among maturing fleas transferred to hosts that do not supply the factor. The processes of vitellogenesis, not those of oogenesis, fail in the absence of the factor. It is suggested that the ‘yolk-forming hormone’ normally secreted by the corpus allatum of the adult insect may only be produced by rabbit fleas when they can obtain the postulated factor. Variations in the quantity of this factor available to fleas on different hosts could explain the observed variations in ovarian activity. Some parallels between the factor and steroid hormone levels in the host’s blood are discussed.

Insekten und Milben als „Freizeitchädlinge”

Insects and mites noxious in vacances of men are named Freizeitschadlinge. There are the females ofCulicidae, Helidae, Simuliidae andTabanidae stinging men, the caterpillars ofThaumatopoea producing urticaria, earworms, swarming flies going in weekend houses for hibernation (Thaumatomyia notata Meigen andMegaselia meconicera Speiser) and swarmingEphemeroptera. Fleas of animals (Spilopsyllus cuniculi Dahle andCeratophyllus gallinae Schrank) can pain the men in weekend houses when their special hosts are driven away. A child has picked upDermanyssus gallinae Degeer in a poultry house, young peoplePhthirus pubis L. on the coast of the Mediterranean sea. Woodhouses are attacked by cerambycid larves and ants, fabrics by grasshoppers and crickets.Sitophilus oryzae L. lived in corn, filling of a punching ball.Dytiscus, Notonecta and other water-insects, also larves ofTipula czizeki de Jong and springtails are found in swimmingpools. Larves ofRhizotrogus and sodworms (Crambus spec.) destroy lawns and golf greens. Mites penetrated in camera appeared photographed on all dias.

A CORRELATION BETWEEN DEVELOPMENT OF THE OVARIES AND OF THE MIDGUT EPITHELIUM IN THE RABBIT FLEA SPILOPSYLLUS CUNICULI.

A Correlation Between Development of the Ovaries and of the Midgut Epithelium in the Rabbit Flea Spilopsyllus Cuniculi

Some Experiments Concerning the Interchange of Rabbit Fleas, Spilopsyllus cuniculi (Dale), between Living Rabbit Hosts

Some Experiments Concerning the Interchange of Rabbit Fleas, Spilopsyllus cuniculi (Dale), between Living Rabbit Hosts

Breeding of the Rabbit Flea (Spilopsyllus cuniculi (Dale)) controlled by the Reproductive Hormones of the Host

THE rabbit flea (S. cuniculi) is a host-specific parasite of the rabbit. Before the outbreak of myxomatosis in Britain all populations of rabbits examined from the mainland were infested and the flea index was high1,2. The first hint that the breeding cycle of the flea was linked to the hormone cycle of the host came from Allan's1 observation that shortly before the breeding season commenced, female rabbits carried an extra load of fleas. Further observation enhanced this view, and Rothschild2,3 suggested that the breeding cycle, especially copulation, was under the influence of the sex hormones of the host. This suggestion was followed up by Mead-Briggs4, who proved that: (a) maturation of the ovaries of female rabbit fleas could only take place on a pregnant female rabbit; (b) that immediately after parturition the fleas from the does were to be found in the nest containing the young rabbits, where they fed on the young and laid eggs.

Breeding of the Rabbit Flea, Spilopsyllus cuniculi (Dale) : Requirement of a ‘Factor’ from a Pregnant Rabbit for Ovarian Maturation

A STUDY of the biology of the European rabbit-flea (Spilopsyllus cuniculi) was commenced by this department when it became apparent that it was an important vector of myxomatosis in Great Britain. A technique for the laboratory culture of the flea was required, but was not rapidly forthcoming. It was repeatedly found that fleas released on domestic or wild rabbits kept in various types of hutches failed to produce eggs. However, Miriam Rothschild1 reported that the flea bred when rabbits were kept under semi-natural conditions in an outdoor enclosure, and with her encouragement a study was made of ovarian development in the flea (Mead-Briggs, A. R., unpublished work).

Myxomatosis in Britain.

IN his article, Dr. C. H. Andrewes1 directs attention to the contrast between the host/vector relationship in Britain and Australia. When we have acquired further information about the biology of the rabbit flea (Spilopsyllus cuniculi) and also other possible arthropod vectors, we may find that a somewhat different set of factors comes into operation in Britain between major epizootics.

The life cycle of the British rabbit trypanosome, Trypanosoma nabiasi Railliet, 1895.

This work was carried out with a strain of trypanosomes isolated by inoculation into domestic rabbits of fleas naturally infected from wild rabbits in Hertfordshire.The course of infection was studied in experimentally infected normal and splenectomized rabbits, in which the incubation period varied from 5 to 12 days. After recovery from the infection, rabbits became immune to re-infection. Immune rabbit serum had no protective action against Trypanosoma lewisi.Attempts to infect other animals with the rabbit trypanosome produced negative results.Young rabbits proved to be more susceptible to infection with this trypanosome, and their parasitaemia lasted longer than in adult rabbits, but the parasite was found to be non-pathogenic to these animals.It was demonstrated that this trypanosome multiplies in the spleen, where the stages of division are confined to the capillaries. Multiplication follows the inoculation of metacyclic trypanosomes from infected fleas or blood forms. It proceeds by division of the nucleus and kinetoplast into four, followed by fission of the cytoplasm, giving rise to four small daughter individuals. These are transformed into trypanosome forms, which are shed into the peripheral blood, where they change into the typical adult trypanosomes.The development in the intermediate host takes place in the gut of the rabbit flea, Spilopsyllus cuniculi, with the production of metacyclic trypanosomes in the hind-gut (posterior station).The nomenclature and synonymy of the rabbit trypanosome are discussed, and it is concluded that its valid name is Trypanosoma nabiasi Railliet, 1895.

Rabbit fleas on wild rabbits and the transmission of myxomatosis.

DURING the course of investigations into myxomatosis on the Heisker or Monach Isles, North Uist, it was suspected that the rabbit flea, Spilopsyllus cuniculi (Dale), was responsible for the carry-over of the disease during the winter of 1952–53. Laboratory experiments confirmed that the rabbit flea could transmit the disease, and this was also shown by Lockley1. Since December 1953 a census of the flea population on wild rabbits has been carried out on an estate near Aberdeen, and the accompanying histogram (Fig. 1) illustrates the results.

Some Epidemiological Observations on Tularemia in California 1927–1951

Summary A study of 266 authenticated cases of tularemia in California occurring from 1927–1951 showed that 81 per cent were contracted from wild rabbits. The jack rabbit appears to be more frequently involved than the cottontail, in contrast with the findings of Eastern writers. Other wild animals found infected were several species of ground squirrels and field mice, and in a few cases the brown rat. Infected arthropods found in California are chiefly ticks, although the role of rabbit fleas deserves further study, and possibly that of deerflies and horseflies. The incidence of tularemia in the decade 1933–1942 was 16 cases a year but it has declined during the last ten years to an average of 6 cases which may in part be due to decreased reporting by clinicians who now have an effective antibiotic at hand. The seasonal occurrence with its peak in summer is associated with rabbit hunting and arthropod vector activity, but there is no correlation with the legal hunting season of cottontail rabbits. Age and sex distributions reflect the opportunity of exposure to wild rabbits. Occupation, even that of butchers, who do not handle wild rabbits plays little or no part in the epidemiology. Cases occur mainly among sportsmen and housewives who dress and cook the game. The incidence of tularemia in California does not warrant its consideration as a major public health problem. An educational effort, particularly in the counties of greatest incidence, might help to prevent infection in hunters and their wives by teaching them how to avoid exposure when handling wild rabbits.