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PubMed1991

Predators of the tick Amblyomma variegatum (Acari: Ixodidae) in Guadeloupe, French West Indies.

Some vertebrate species in Guadeloupe are predators of free or parasitic stages of Amblyomma variegatum (Fabricius). Among birds, 1.9% of the 421 identified animals found in the stomachs of grackles (Quiscalus lugubris), 1.6% of the 364 animals found in the stomachs of free-ranging chickens, and 0.3% of the 4642 animals found in the stomach of cattle egrets (Bubulcus ibis) were A. variegatum ticks. The most efficient predator of ticks was the tropical fire ant, Solenopsis geminata, which was observed to only attack engorged stages of ticks. An average of 8% of the 564 individual ticks or batch of ticks released on the ground, mainly in a grass environment, were attacked by this ant species. Mice (Mus musculus) and mongooses (Herpestes auropunctatus) feed on engorged nymphs and female ticks. None of the 15 strains of entomophagous nematodes, genera Steinernema and Heterorhabditis, experimentally put in contact with engorged larvae and nymphs were able to parasitize them. In the laboratory, the insects Megaselia scalaris (Diptera) and Tineola sp. (Lepidoptera) were occasionally found to feed on engorged and unfed ticks, respectively.

Animals↗
PubMed1991

Acaricide susceptibility of Amblyomma variegatum (Acari:Ixodidae) from Puerto Rico and Guadeloupe.

Base-line data on acaricide susceptibility of larvae and of larvae and nymphs of the tropical bont tick, Amblyomma variegatum (Fabricius), from Puerto Rico and Guadeloupe were collected on 14 and six compounds, respectively. Nymphs 7-8 weeks old from Puerto Rico and Guadeloupe, and larvae 3-4 weeks old from Guadeloupe, were exposed for 24 or 48 h to residues of acetone dilutions of technical-grade or commercial formulations of acaricides on disposable glass pipettes. Effectiveness of the acaricides in killing nymphs (LC50) from Guadeloupe and Puerto Rico ranged from 0.0001% for deltamethrin2 to 0.269% for malathion. For Puerto Rico, the susceptibility to toxaphene and amitraz, but not to dioxathion, increased with increasing age of nymphs. Nymphs from Guadeloupe were 9.5 times more susceptible to chlorpyrifos than nymphs from Puerto Rico. The susceptibility of larvae from Guadeloupe to acaricides tested ranged from LC50 0.000012% for deltamethrin to 0.0141% for ethion. There was no evidence of development of acaricide resistance in ticks from Guadeloupe or Puerto Rico.

Animals↗
PubMed1991

Host associations and seasonal abundance of immature Ixodes persulcatus (Acari: Ixodidae) in a Lyme-disease-endemic area in China.

Ticks of nine small mammal species were studied in an area of endemic Lyme disease in Hailin County, Heilongjiang Province, from 1 May to 10 October 1986. The bulk (93%) total small mammal captures were Apodemus speciosus (45%), Clethrionomys rufocanus (31%), A. agrarius (11%) and Eutamias sibiricus; (5%): these host species accounted for 97% of the 162 ticks collected. Ixodes persulcatus Schulze were most abundant on E. sibiricus (0.64 larvae and 0.08 nymphs/squirrel), and less abundant on A. agrarius (1.16 larvae/mouse), A. speciosus (0.38 larvae/mouse) and C. rufocanus (0.37 larvae and nymphs/vole). The seasonal abundance pattern of larval I. persulcatus on four small mammal species appears as a bimodal peak (June and September), but nymphal I. persulcatus has a monomodal peak during spring. The prevalence of immature I. persulcatus on four small mammal species may play an important role in the epidemiology of Lyme disease in Hailin County.

Animals↗
PubMed1991

The life cycle of Amblyomma parvum Aragao, 1908 (Acari: Ixodidae) under laboratory conditions.

A colony of Amblyomma parvum was started with engorged females collected from cattle in the Province of Salta (25 degrees 01' S, 63 degrees 56' W), Argentina. The progeny of those ticks were fed on rabbits and the non-parasitic stages maintained at 27 +/- 1 degrees C, 83-86% RH in darkness. The life cycle (prefeeding period not evaluated) had a mean duration of 99.6 days. The mean time (days) for the different phases of the cycle were as follows: feeding period of females, 8.0; pre-oviposition period, 5.7; oviposition period, 17.5; minimum incubation period of the eggs, 31.8; feeding period of larvae, 3.2; premoult period to nymphs, 10.9; feeding period of nymphs, 4.7; premoult period to adults, 17.8. The oviposition pattern was typical of an ixodid tick, including a linear relationship between weights of engorged females and the number of eggs laid (r = 0.8659). The males increased 18% in weight after feeding on hosts (P less than 0.01). The mean recovery rates of larvae, nymphs and females were 28.2%, 95.3% and 90.7%, respectively. The nymphs moulting to females were heavier (6.8 +/- 0.69 mg) than those moulting to males (3.2 +/- 0.29 mg) (P less than 0.01). A comparison of biological values of A. parvum with American and non-American Amblyomma species is presented.

Animals↗
PubMed1991

Immunocytochemical localization of an insulin-like substance in the synganglion of the tick Ornithodoros parkeri (Acari: Argasidae).

Immunocytochemical staining based on the peroxidase-antiperoxidase method has shown that some neurosecretory cells (NSC) in the synganglion of the adult female tick Ornithodoros parkeri react with an antibody to bovine insulin. There are 18 regions of paraldehyde fuchsin-positive NSC of which three regions showed specific insulin-like immunoreactivity: anterolateral cheliceral, anteromedial stomodeal and posterior opisthosomal. Immunoreactivity can also be found in the extracellular surface of the neurilemma of the synganglion. This suggests a possible neurohemal site and release of neurohormone in a diffuse manner.

Animals↗
PubMed1991

Role of genital sex pheromones in Amblyomma americanum and A. maculatum (Acari: Ixodidae).

Amblyomma americanum and A. maculatum were studied to determine if genital sex pheromones were present, as reported in Dermacentor species. Chemical analysis of methanol extracts of the anterior reproductive tracts (source of the genital sex pheromone) of A. americanum and A. maculatum confirmed the presence of the same fatty acids that act as components of the genital sex pheromone in Dermacentor variabilis and D. andersoni. In both Amblyomma species, removal of the anterior reproductive-tract of fed females eliminated the male copulatory response. For A. americanum, use of anterior reproductive tract extracts made with water, methanol, ether and hexane elicited significant probing and copulatory responses by conspecific males. However, in A. maculatum, use of anterior reproductive-tract extracts made with water, methanol, ether, chloroform:methanol (4:1), hexane and pentane did not restore mating response by males. Treatment with known components of Dermacentor genital sex pheromones elicited weak but significant responses in A. americanum, but did not restore male mating responses in A. maculatum. These results indicate that genital sex pheromones exist in A. americanum and are not restricted to the genus Dermacentor. Characteristics of the Amblyomma genital sex pheromone, however, do differ considerably from those in Dermacentor. No genital sex pheromone was present in A. maculatum.

Animals↗
PubMed1991

Spatial distribution of the Karoo paralysis tick Ixodes rubicundus (Acari: Ixodidae) within a false upper Karoo veld type.

Spatial distribution of the Karoo paralysis tick (Ixodes rubicundus) has been studied in a paralysis enzootic area of the southwestern Orange Free State. Significantly more females than males were collected from the vegetation. Most ticks (99%) used grass as questing sites at a height of approximately 45 cm (range 10-97 cm), which correlates with the size of host animals. No significant differences between the questing height of male and female ticks were evident. The ticks were found on most of the grass species present and, except for the genus Eragrostis, no specific preference was evident. When questing, the capitulum of I. rubicundus is usually (90%) directed towards the ground. Seventy-eight percent of the ticks occurred singly on a specific grassblade or flowerhead. In those cases where two ticks occurred together, no sexual aggregation was evident. Most ticks occurred under or close (mean = 62 cm) to the crown cover of specific shrub or tree species. These plant species were characterized by a dense crown cover with a mat of decaying leaf litter underneath. The preference of the tick for wild olive trees (Olea europaea africana) suggests that, except for the physical characteristics of this tree species, host factors may also be important. Significantly more ticks were distributed on the cooler, more protected southern sides of vegetation in comparison to the northern sides.

Animals↗
PubMed1988

Effect of mercury vapour on the non-protein thiol content and respiration rate of eggs of the cattle tick Boophilus microplus (Acari: Ixodidae).

With continuous and ultimately lethal exposure of eggs of Boophilus microplus to mercury vapour, respiration and non-protein thiol decreased to low levels. With sub-lethal exposure, respiration decreased initially and then increased, whereas non-protein thiol (largely glutathione) increased initially and then decreased. This initial increase in glutathione (GSH) which probably resulted from an attempt by the organism to control or reverse the biochemical lesion, did not arise from the oxidized form (GSSG) through a shift in the equilibrium from right to left thus: 2GSH in equilibrium GSSG + 2H+ + 2e-. The significance of the results are discussed in relation to theories of GSH function and of Hg toxicity. The possible application of mercurials in tick control is discussed.

Animals↗
PubMed1986

Field tests of the response of female Amblyomma variegatum (Acari:Ixodidae) to the synthetic aggregation-attachment pheromone and its components.

Fifty percent of an Amblyomma variegatum female population were able to find upwind-positioned targets containing the synthetic aggregation-attachment pheromone of this species or the pheromone component o-nitrophenol alone. The ticks were not attracted to the other components of the pheromone: methyl-salicylate and pelargonic acid. The mean time required for the ticks to reach a target at 1 m from the starting point was 3 min and 20 s.

Animals↗
PubMed1992

Temperature influence on life table statistics of the chicken mite Dermanyssus gallinae (Acari: Dermanyssidae).

An age-specific life table for the chicken mite Dermanyssus gallinae (DeGeer, 1778) was based on various observations carried out at 25 degrees C. The generation time was calculated to be 16.8 days; the intrinsic rate of natural increase was 0.12 per day, and the net reproductive rate was 7.2. A nonlinear function was found satisfactory to describe the developmental rate of the different immature life-stages at temperatures below 40 degrees C. The stage-specific survival of the immature life-stages was generally high between 10 and 37 degrees C, but decreased quickly outside this temperature range. Most of the eggs were laid during the first three weeks of the adult life. The proportion of surviving females rapidly decreases after moulting to the adult stage. At a temperature of 30 degrees C, the highest number of eggs (3 eggs per day) was laid.

Animals↗
PubMed1990

Anatomy and ultrastructure of the reproductive systems of Acarus siro (Acari: Acaridae).

Anatomy and ultrastructure of the female and male reproductive system in Acarus siro L. were investigated by light and electron microscopy. The female system consists of paired ovaries of nutrimentary type in which oogonia and oocytes are connected by bridges with a large central cell. The oviducts empty into the uterus, which passes into preoviporal duct lined by cuticle, and opening as a longitudinal slit (oviporus). An elongated accessory gland composed of one type of secretory cell is located along each oviduct. The copulatory opening occurs at the posterior margin of the body and leads, via the inseminatory canal, to the receptaculum seminis, consisting of the basal and saccular part. Both inseminatory canal and basal part of receptaculum seminis are lined by cuticle, whereas the wall of the sac is formed by cells covered only by long, numerous microvilli. The basal part of the receptaculum seminis joins the ovaries via two lumenless transitory cones. The male reproductive system contains paired testes, in which spermatogonia tightly surround the central cell. The proximal part of the paired vasa deferentia serves as a sperm reservoir, while the distal one has a glandular character. An unpaired, cuticle-lined ejaculatory duct opens into the apex of the aedeagus. The single accessory gland is located asymmetrically at the level of, or slightly posterior to, coxae IV. The structure of the genital papillae, which are topographically related to the genital opening in both sexes, is also briefly described.

Animals↗
PubMed1990

Transmission of Demodex flagellurus (Acari: Demodicidae) in the house mouse, Mus musculus, under laboratory conditions.

Transmission of Demodex flagellurus Bukva, 1985 inhabiting the preputial and clitoral glands of the house mouse, Mus musculus L., was studied in mating experiments using pairs of infested, feral X mite-free, white laboratory mice. Spontaneous transfer of mites between sexually active hosts of the opposite sex, presumably through copulation, is reported for the first time for the hair-follicle mites under controlled conditions. Transfer of mites from host mother to her progeny was also proven. A comparatively low transmission effectiveness was observed in both modes of transmission, being 9.5% in adult-to-adult transmission and 14.8% in mother-to-young transmission.

Animals↗
PubMed1990

Phoretic association between Macrocheles muscaedomesticae (Acari: Macrochelidae) and flies inhabiting poultry manure in Peninsular Malaysia.

The phoretic association between Macrocheles muscaedomesticae and flies that inhabited poultry manure in a poultry farm in Sungai Buloh, Selangor, Malaysia was studied. The effects of temperature, relative humidity and fly abundance on phoretic rates also were investigated. The most abundant fly species found was Musca domestica; Musca sorbens, Chrysomyia megacephala and Ophyra chalcogaster were present in relatively large numbers. Representatives of ten families of mites were found on collected Mu. domestica. The most common mite was Ma. muscaedomesticae (Macrochelidae), found on all four species of flies mentioned above. The highest infestation (2.0%) occurred on O. chalcogaster but Mu. domestica had the highest average number infested (5.7). The ventral part of the housefly's abdomen was the most common site of mite attachment. Usually only one mite was found attached per fly. The highest phoretic rate recorded was 64.4 Ma. muscaedomesticae per 1000 Mu. domestica. There was no correlation between phoretic rates and Ma. muscaedomesticae abundance, nor was relative humidity a factor. However, a positive correlation was recorded in this host species between phoretic rates and temperature.

Animals↗
PubMed1989

Instar development and disengagement rate of engorged female winter ticks, Dermacentor albipictus (Acari:Ixodidae), following single- and trickle-exposure of moose (Alces alces).

Seven hand-reared moose (Alces alces) calves and one yearling were infested with 30,000 larvae each of the winter tick. Dermacentor albipictus, either by single- or trickle-exposure (1000/day). They were examined weekly for instar changes from September/October until late May. By 2 and 3 weeks post-exposure, most larvae on single- and trickle-infested moose, respectively, had fed and molted to nymphs. Thereafter, tick development was similar between both infestation techniques. Nymphs dominated the tick population from October to mid-February, and adults from mid-February to May. The peak of host disengagement by engorged females was late March in both years. Weights of engorged females from calf moose declined over time during the disengagement period.

Animals↗
PubMed1989

Effect of Dermacentor albipictus (Acari:Ixodidae) on blood composition, weight gain and hair coat of moose, Alces alces.

The physiological effects of the winter tick, Dermacentor albipictus, on moose, Alces alces, were investigated. Blood composition, weight gain, food intake and change in the hair coat of moose calves, four infested with D. albipictus larvae, and eight uninfested, were monitored. Infested moose groomed extensively, apparently in response to feeding nymphal and adult ticks, and developed alopecia. Other clinical signs included: chronic weight loss, anemia, hypoalbuminemia, hypophosphatemia, and transient decreases in serum aspartate transaminase and calcium during the period of nymphal and adult female tick engorgement. Infested animals did not become anorexic. Two moose with severe hair loss had increases in gamma globulin shortly after the onset of female tick engorgement. Results suggest that alopecia is associated with tick resistance. Animals that groom and develop hair loss likely carry fewer ticks and therefore suffer less severely from blood loss.

Alopecia↗
PubMed1989

Resistance in cattle against Rhipicephalus appendiculatus with an assessment of cross-resistance to R. pulchellus (Acari: Ixodidae).

A comparison of the yield of engorged nymphs of Rhipicephalus appendiculatus and R. pulchellus was carried out between cattle highly resistant to R. appendiculatus but susceptible to R. pulchellus, and cattle and rabbits susceptible to both species. Resistant cattle yielded fewer and smaller R. appendiculatus nymphs than either susceptible cattle or rabbits. More nymphs of both tick species dropped from susceptible cattle but no differences were detected in the mean weight of engorged R. pulchellus nymphs fed on R. appendiculatus-resistant and susceptible cattle, although resistant animals yielded more nymphs of R. pulchellus than of R. appendiculatus. An acute inflammatory reaction, accompanied by intense pruritus and grooming, was observed in the ears of the resistant cattle infested with R. appendiculatus, but no reaction was detected in the opposite ears where R. pulchellus was feeding. The low cross-resistance between these two closely related tick species suggests that different antigens may be involved in the development of resistance in cattle to different tick species.

Animals↗
PubMed1989

Sites of attachment and density assessment in Amblyomma americanum (Acari: Ixodidae) on nursing beef calves.

Primary attachment sites of male, female, and nymphal Amblyomma americanum (L.) on nursing beef calves were the axillary, inguinal and perianal areas of the body. About 50% of all larvae fed on the ears. A density assessment method which uses the number of A. americanum on less than or equal to 5 body areas to predict the total number of ticks (tick burden) on the left side of a calf is presented. Estimates of tick burden for male, female, nymphal and larval A. americanum each require examination of the axillary, inguinal, and perianal body areas. In addition, to estimate larval and male A. americanum, the neck, dewlap and brisket require examination as do the ears for estimates of nymphs and larvae. Mean tick burden in a herd of calves can be estimated by an examination of from 14 to 100% of all calves depending on the level of precision required for the estimate.

Animals↗
PubMed1990

Cattle breed alters reproduction in Amblyomma americanum (Acari: Ixodidae).

Female Amblyomma americanum [L.] that feed on Bos taurus cattle weigh significantly (P = 0.05) more (mean = 505.4 mg) than females that feed on B. indicus x B. taurus cattle (mean = 450.7 mg) but not females that feed on B. indicus cattle (mean = 489.7 mg). Females that feed on B. taurus cattle lay more eggs (mean = 3492) and produce more larvae (mean = 3243) than females that feed on B. indicus cattle (mean = 3103 eggs; 2925 larvae) or B. indicus x B. taurus cattle (mean = 2961 eggs; 2759 larvae). The number of eggs produced per unit engorged female weight is not significantly different in ticks that feed on B. taurus and B. indicus x B. taurus cattle.

Animals↗