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At least 19 recordsLinked to original sources

PubMed1985

Pentastomid nymph from the brain of a squirrel monkey (Saimiri sciureus). I. Morphology of the nymph.

A Pentastomid nymph of the genus Porocephalus was identified following its removal from the brain-meningeal interface of a squirrel monkey, Saimiri sciureus. It was characterized by two inner and two outer hooks adjacent to the mouth opening, the presence of accessory lobes (or spines) on the outer hooks, a vertical slit-like mouth opening surrounded by a U-shaped conformation of integument, and annulation of the body surface. Stigmata, representing the openings of integumental chloride cells, were present on the dorsum of the head and tail, on anterior aspects of annulae on the body, and on anterior and posterior edges of annulae located on the ventral surface of the tail. These openings were not present on integumental folds at the bases of the inner and outer hooks, on the dorsal aspect of the tail flap, or in the deep grooves separating annulae. Although it was not possible to determine the species, based on the number of annulae this specimen may represent P. stilesi.

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PubMed1979

The production of nymphs of Hyalomma anatolicum anatolicum for experimental infection with Theileria annulata.

Methods are described for the production of nymphs of Hyalomma anatolicum anatolicum for later use in transmission experiments with Theileria annulata where the timing of the application of nymphs to infected cattle needs to be accurately controlled. Larvae are fed on the torsos of rabbits where approximately 98% undergo a two-host feeding cycle. This cycle is interrupted 2 days after the first larvae moult into nymphs by killing the rabbits and the nymphs are then collected with a suction pump. Nymphs produced by the interrupted larval feeding method feed well on cattle, in regard to timing of detachment and weight, compared with nymphs produced by interrupted feeding on rabbits.

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PubMed1992

Immunization of rabbits against nymphs of Amblyomma hebraeum and A. marmoreum (Acari: Ixodidae).

Himalayan rabbits immunized with homogenates prepared from nymphs of Amblyomma hebraeum Koch and A. marmoreum Koch ticks developed humoral and probably also cell-mediated immunity to their respective homogenates. Beta and gamma globulin levels and numbers of eosinophils and neutrophils increased significantly in inoculated rabbits. The recipient animals developed resistance to homospecific nymphal infestations. Cross resistance between the two species was not evaluated. Nymphs of both species that fed on inoculated rabbits demonstrated slightly shorter feeding periods, and their mean weights were significantly lower than nymphs that fed on Quil 'A' adjuvant-inoculated rabbits or on naive rabbits. Significantly higher proportions of nymphs from immunized animals failed to moult when compared with nymphs that fed on the two control groups. These parameters indicate that the inoculated rabbits had acquired protective immunity against nymphs of both ticks.

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PubMed1992

Inability of Ixodes cookei and Amblyomma americanum nymphs (Acari: Ixodidae) to transmit Borrelia burgdorferi.

The vector competency of Ixodes cookei Packard and Amblyomma americanum (L.) for Borrelia burgdorferi was studied using Syrian hamsters. Ixodes dammini Spielman, Clifford, Piesman & Corwin were used as controls. Darkfield and immunofluorescent examinations of midgut diverticula revealed B. burgdorferi spirochetes in 32 of 36 (88.9%) I. dammini larvae, 5 of 36 (13.9%) I. cookei larvae, and 7 of 36 (19.4%) A. americanum larvae within 48 h after feeding on infected Syrian hamsters. B. burgdorferi were also observed in the midguts of 94 of 107 (87.8%) I. dammini nymphs that developed from the fed larvae. However, none of 30 I. cookei nymphs was positive for spirochetes and only 1 of 60 (1.7%) A. americanum nymphs was found positive for B. burgdorferi. Nymphs of each tick species, reared from larvae that had fed on infected hamsters, were allowed to feed on uninfected hamsters to determine their ability to transmit B. burgdorferi. Transmission was demonstrated only by I. dammini nymphs.

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PubMedDate not supplied

[Sexual dimorphism of the larvae and nymphs of the taiga tick--Ixodes persulcatus].

Manifestations of sexual dimorphism at the preimaginal phase was studied on the laboratory culture of Ixodes persulcatus. It has been found out that larger engorged larvae produce, in general, larger nymphs and smaller larvae produce smaller nymphs. The classification of engorged nymphs into large (over 2.9 mm) and small ones (less than 2.9 mm) has made it possible (with 100% probability) to obtain females from the former and males from the latter. Differences in linear sizes of scutum, gnathosoma and its appendages in male and female nymphs were determined that has made possible the identification of sex in hungry nymphs.

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PubMed1992

A comparison of the attraction of nymphs and adults of the ticks Amblyomma hebraeum and A. variegatum to carbon dioxide and the male-produced aggregation-attachment pheromone.

The attraction of nymphs of the ticks Amblyomma hebraeum and A. variegatum to CO2 alone and CO2 together with the male-produced aggregation-attachment pheromone (AAP) was investigated. Matching experiments on the attraction of the adults of the two species were run for comparison. Nymphs of A. hebraeum were strongly attracted to sources of CO2 and CO2/AAP at distances of 10 and 15 m. At distances of 20 and 25 m significantly more nymphs were attracted to CO2/AAP than to CO2 alone. Adults of A. hebraeum were not attracted to CO2 alone at any distance; these ticks were attracted to CO2 and AAP together for distances of up to 25 m. The patterns of attraction of nymphs and adults of A. variegatum at 10 m were similar to those recorded in A. hebraeum.

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PubMed1990

Circadian rhythms of locomotor activity in cockroach nymphs: free running and entrainment.

The temporal organization of locomotor activity was investigated in nymphs of the cockroach Leucophaea maderae. Approximately 40% of the animals examined between 1 and 50 days of age exhibited a circadian activity rhythm in constant darkness (n = 172) with an average free-running period of 23.7 +/- 0.68 hr. Twelve of 17 animals in which activity was recorded for most or all of the final instar also exhibited periods of rhythmic activity. The rhythms of the nymphs could be entrained by light-dark (LD) cycles with periods of 22, 24, or 26 hr. In contrast, neither maternal influences during embryogenesis nor hatching from the egg was effective in synchronizing the rhythms. Although adult cockroaches can be readily entrained by temperature cycles, in nymphs temperature appeared at best to be a weak zeitgeber. Embryonic exposure to an LD cycle until 6 days prior to egg hatch was effective in synchronizing the activity rhythms of the nymphs, indicating that differentiation of an entrainable pacemaking system occurs prior to hatching.

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PubMedDate not supplied

[The development of methods for the absolute count of the population of ixodid pasture ticks in open landscapes. 3. The count of hungry Dermacentor nuttalli Olen., 1919 larvae and nymphs in the steppe regions of the Transbaikal area].

Methods for absolute registration of the number of hungry larvae and nymphs directly in the places of their natural habitation have been elaborated. Specific features of the activation of these phases in Transbaikal conditions have been studied. Peaks of their seasonal activity can be observed in July. It has been shown that the results of single (during seasonal peak in their number) capture of larvae and nymphs from all animal holes over a 100 m2 area can be used for characterization of density. Single capture accounts for 9-15% larvae and 12-16% nymphs of the total number of activized individuals. To assess reliably mean larval and nymph density, with the inadequacy of the results of absolute registration being 30%, not less than 100-130 areas should be examined.

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PubMed1990

Development and infectivity of Anaplasma marginale in Dermacentor andersoni nymphs.

The development of Anaplasma marginale was studied in Dermacentor andersoni nymphs after they had fed on a calf with ascending Anaplasma infection. Gut tissues were collected on day 4 of tick feeding, from newly replete (fed) nymphs and on postfeeding days (PFD) 5, 10, 15, 20, and were processed for light and electron microscopy to determine density of A marginale colonies. Homogenates of gut tissues were prepared from nymphs collected on the same days and inoculated into susceptible, splenectomized calves to test for infectivity. Anaplasma colonies were detected in gut cells on PFD 5, 10, 15, and 20. Although colony density appeared to be higher on PFD 10 and 15, differences were not significant. Nymphal type-1 colonies were detected in highest numbers on PFD 5 and 10, transitional colonies were seen in highest numbers at PFD 10 and 15, and nymphal type-2 colonies were observed only on PFD 20. Gut homogenates that were collected from ticks at 4 days of feeding, when newly replete, and on PFD 20 caused anaplasmosis when injected into susceptible calves, but homogenates made from ticks collected on PFD 5, 10, and 15 were not infective. The data indicate that of the colony types of A marginale that develop in replete nymphs, nymphal type-1 and transitional colonies may contain organisms that are not infective for cattle.

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PubMed1992

Responses of the ticks Amblyomma hebraeum and A. variegatum to known or potential components of the aggregation-attachment pheromone. IV. Attachment stimulation of nymphs.

Ten known or potential components of the aggregation-attachment pheromone (AAP) of the ticks Amblyomma hebraeum and A. variegatum, as well as a mixture of these components and extracts of prefed males of the two species, were tested as attachment stimulants for nymphs. Unfed nymphs were confined in linen bags on the ears of rabbits that had been treated with the test compounds, mixture or extracts; the numbers attached were recorded after 24 h. In A. hebraeum, attachment was induced by four compounds (2-methyl propanoic acid, methyl salicylate, o-nitrophenol and salicylaldehyde), the mixture and extracts from both species. In A. variegatum, attachment was induced by three compounds (methyl salicylate, o-nitrophenol and salicylaldehyde), the mixture and extracts from both species. Methyl salicylate and o-nitrophenol are primary components of the AAP of both A. hebraeum and A. variegatum. 2-methyl propanoic acid is a species-specific attachment stimulant for A. hebraeum. Salicylaldehyde, a phenolic compound, is not a naturally occurring AAP component. Nymphs of both species respond to fewer attachment stimulants than the adults and, as shown by their respective host ranges, are less dependent on the AAP in the regulation of attachment than the adults.

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PubMed1988

Field sampling of unfed nymphs of Amblyomma hebraeum.

Unfed nymphs of Amblyomma hebraeum Koch, 1844 shelter under debris on the soil surface and become active in host-seeking when stimulated with carbon dioxide. The active nymphs are not attracted to sources of carbon dioxide and hence cannot be effectively sampled using static carbon dioxide traps. However, these nymphs will cling to flannelette and can be sampled by flagging. Larger numbers are recovered if the soil surface is sampled using a vacuum device.

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PubMed1990

Infection rates with Cowdria ruminantium of nymphs and adults of the bont tick Amblyomma hebraeum collected in the field in Zimbabwe.

Cowdria ruminantium (heatwater) infection rates of field populations of the bont tick, Amblyomma hebraeum, were determined at two locations in the southern lowveld of Zimbabwe. At Mbizi Quarantine Station, unfed adult males and females, and nymphs were collected at intervals over a 2-year period using traps. At Lemco Ranch, engorged nymphs were collected on three occasions from weaner calves and allowed to moult to adults. The unfed ticks were fed in small pools on heartwater-susceptible sheep, some of which became infected. The infection rates of the ticks were then estimated statistically. Depending on the date of collection and locality, these rates were in the range 0.0-44.9% for males, 20.0-36.1% for females and 0.0-13.4% for nymphs. Most of these rates are considerably higher than those previously believed to occur.

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PubMed1976

The feeding behaviour of larvae, nymphs and adults of Rhipicephalus appendiculatus.

The pre-feeding and feeding periods of larvae, nymphs and adults of Rhipicephalus appendiculatus on rabbits (Oryctolagus cuniculus) were investigated. Larvae and nymphs required at least 8-9 days after hatching and moulting respectively before they could attach and start feeding, while adults required at least 6-9 days. But longer periods of starvation improved the proportion of ticks that successfully fed. After attachment, there was always an initial period of slow feeding, which was followed by a phase of very rapid feeding before the engorged ticks detached from the host. Larvae detached 4-5 days after attachment, nymphs detached after 5-6 days and adults detached 7-9 days after attachment.

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PubMed1991

Effectiveness of carbaryl applications for the control of Ixodes dammini (Acari: Ixodidae) nymphs in an endemic residential area.

Ground applications of carbaryl in early June 1989 reduced populations of nymphal Ixodes dammini Spielman, Clifford, Piesman & Corwin by 100% in five 0.4-ha residential sites 72 h after application. High levels of control (greater than 90%) persisted for almost 2 mo. Five nymphs were recovered at the periphery of the sprayed plots at two sites 2 wk after spraying and nine nymphs were collected at the periphery of the sprayed plots at three of the sites 4-5 wk after application. At 8 wk after application, I. dammini nymphs were recovered within three of the sprayed plots. Chemical control of nymphal I. dammini may be a viable management practice for homeowners living in endemic areas to reduce the chances of acquiring Lyme disease.

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PubMed1992

Tick sweep: modification of the tick drag-flag method for sampling nymphs of the deer tick (Acari: Ixodidae).

We describe a version of the standard tick drag-flag modified for use in close-growing and tangled vegetation, as well as under ornamental shrubbery and fallen branches. Two major features of the sweep are: (1) it allows the user to remain upright with the flag parallel to the ground, thus sampling effectively beneath low and fallen branches and around shrubs, as well as capturing host-seeking ticks in advance of the operator; and (2) the use of a flannel rubberized-laminate fabric (crib sheet) for the flag that is snag-proof and highly durable in dense and thorny vegetation. In simultaneous 100-m samples, the sweep was as effective as the 1-m standard tick drag for capturing nymphs of the deer tick, Ixodes dammini Spielman, Clifford, Piesman & Corwin, where understory vegetation was sparse, but was twice as effective in dense vegetation, capturing significantly more I. dammini nymphs. The sweep also captured nymphs of the American dog tick, Dermacentor variabilis (Say); rabbit tick, Haemaphysalis leporispalustris (Packard); and lone star tick, Amblyomma americanum (L.).

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PubMed1985

Pentastomid nymph from the brain of a squirrel monkey (Saimiri sciureus). II. Morphology of the host response.

A Porocephalus nymph found in the meninges of a squirrel monkey was encapsulated by connective tissue cells and fibrils presumably derived from the pia mater. The capsule was composed of an inner layer (IL) adjacent to the nymphal integument and an outer layer (OL) adherent to the brain surface. Separating the two layers was a capsular space. The IL was lined by a granular material adjacent to the nymph surface and possessed impressions of annulae and the apical pits of chloride cells. The surface of IL facing the capsular space was characterized by a monolayer of cells possessing extensive anastomosing plasmalemmal processes. The OL was composed of several tiers of fibroblasts and associated collagen fibrils that adhered to the brain surface in the form of a thickened pia mater. It is suggested that the capsule was formed by a modification of the pia that isolated the nymph and created an "intracapsular space" with specialized lining cells to facilitate fluid exchange.

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PubMed1976

Accumulating process and concentration ratios of ingested blood meals in larvae and nymphs of ten species of ticks.

The accumulating process and concentration ratios of ingested blood meals in the larvae and nymphs of Amblyomma testudinarium, Haemaphysalis campanulata, H. concinna, H. formosensis, H. hystricis, H. kitaokai, the bisexual and parthenogenetic strains of H. longicornis, H. megaspinosa, and Ixodes persulcatus on rabbits and Argas japonicus on chickens were comparatively investigated. The larvae and nymphs of the ixodid ticks examined and the larvae of A. japonicus concentrated the ingested blood meals up to about 3 times. In general, the larvae showed low concentration ratios due to their tendency to imbibe a certain proportion of non-blood components. The nymphs generally showed high concentration ratios. H. kitaokai belongs to the subgenus Alloceraea, the members of which are unique rapid feeders. It showed a high activity in concentrating ingested blood meal and presented the same general pattern of feeding as the other ixodid ticks which are very slow feeders.

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PubMed1977

Theileria mutans the infectivity for cattle of parasites derived from prefed Amblyomma variegatum nymphs.

A steer was infected with Theileria mutans (Aitong) by application of infected Amblyomma variegatum nymphs. Uninfected A. variegatum larvae were applied to this steer when piroplasms developed. The resultant (and infected) A. variegatum nymphs were applied to the ears of rabbits. Equal numbers of ticks were removed daily from rabbits and ground in Eagles Minimal Essential Medium. The infectivity of the supernatant fluid was tested in cattle. The produced supernatant fluids were infective between days 3 to 7 but noninfective on days 0, 1 and 2. The feeding of A. variegatum on cattle and rabbits was compared and the increase of haemoglobin in the supernatant was correlated with the weight increase of the nymphs. It is hoped that infective T. mutans (Aitong) stabilate derived from ticks can be produced using this information.

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