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At least 379 records · Page 21Linked to original sources
PubMed1987

The development of Amblyomma americanum and Dermacentor variabilis (Acari: Ixodidae) fed on rabbits immunized with tick hemolymph.

The possibility of interfering with the normal function of tick hemolymph using antihemolymph antibodies taken in with the bloodmeal, was investigated. Cell free hemolymph from replete Amblyomma americanum and Dermacentor variabilis ticks was used to immunize rabbits. Immunized rabbits developed high antihemolymph antibody titers (ca. 10(5)) and had no ill side effects. Rabbits were simultaneously infested with larvae, nymphs, and adult ticks. The biological performance of ticks fed on immunized rabbits was virtually identical to that of ticks fed on nonimmunized rabbits. Usually, the mean engorgement weights of nymphs and females and the weights of the egg masses of both species were slightly higher for ticks fed on the nonimmunized rabbits but differences were not significant (P greater than 0.05) due to a large standard deviation. The possibility of deactivating a single hemolymph component with specific antibodies is discussed.

Animals↗
PubMed1993

Climate and cuticular hydrocarbon variation in Rhipicephalus sanguineus ticks (Acari: Ixodidae).

An association between the climate and variation of the cuticular hydrocarbon pattern was found for several populations of Rhipicephalus sanguineus ticks. Extreme parameters of climate (absolute minimal and maximal temperatures) correlated positively with six compounds (mainly methylalkanes) detected in cuticular hydrocarbon mixtures. In the light of work conducted on cuticular transpiration in arthropods and biochemical phase changes in cuticle lipids, it is suggested that the adaptation of ticks to potential colonization areas is accomplished by detectable changes in cuticular hydrocarbon relationships. These tick strains can be biochemically determined and their adaptation potential, analyzed.

Alkanes↗
PubMed1990

On the morphology and organization of the eye of unfed adult Rhipicephalus evertsi mimeticus (Acari: Ixodidae).

Investigations by scanning and transmission electron microscopy and freeze-etching revealed that eyes of adult Rhipicephalus evertsi mimeticus consist of a lens and photoreceptor cells, which are separated by an acellular layer and the hypodermis. The lens contains numerous pore channels, which open beneath the epicuticula of the outer portion, converge uninterrupted to the inner closure and end in approximately 420 pore fields. The inner closure of the lens is formed as a deep circular invagination. Beneath the hypodermis and perpendicular to the lens, a group of approximately 20 highly differentiated photoreceptor cells in a rosette-like arrangement is localized within the invagination of the lens. Each photoreceptor cell is characterized terminally by numerous, tightly packed and parallel-running microvilli, which are oriented perpendicularly to the lenticular pore channels.

Animals↗
PubMed1987

Effects of temperature and relative humidity on development times and mortality of eggs from laboratory and wild populations of the European house-dust mite Dermatophagoides pteronyssinus (Acari: Pyroglyphidae).

As part of a study on passive physical control of house-dust mites, a total of 6000 eggs from a population of Dermatophagoides pteronyssinus (Trouessart, 1897) from 17-year-old laboratory cultures were incubated at 60 temperature and relative humidity combinations between 10-35 degrees C and 55-100% RH. Eggs hatched at every combination, although mortality and development time increased between 10-20 degrees C and 30-35 degrees C and below 65% RH. Optimum conditions were 35 degrees C and 80-85% RH. In temperate dry conditions, eggs from a wild population were found to be more resistant to mortality: they developed faster, with 7 times lower mortality than eggs from the laboratory population. This may have been because the laboratory population had become acclimated to the constant near-optimum conditions at which it was kept. Therefore it has been suggested that where laboratory cultures have been used in studies relating to passive physical control, caution should be taken in applying the conclusions to wild populations in the natural house-dust environment.

Animals↗
PubMed1987

Ticks (Acari:Ixodidae) of the Blue and White Nile ecosystems in the Sudan with particular reference to the Rhipicephalus sanguineus group.

Twenty-four adult ixodid tick species, infesting livestock and some wildlife hosts along the Blue and White Nile in the Sudan, were identified. Three species, Boophilus geigyi, Rhipicephalus camicasi and R. bergeoni, were recorded for the first time from the Sudan. Tick numbers on indigenous breeds of cattle (Bos indicus) were relatively low, ranging between 17.1 and 40.5 per animal. Young cattle grazing with the herd carried significantly fewer ticks than older animals. With the exception of B. annulatus and R. simus, which have extended their distribution further north into Blue Nile, Gezira and Khartoum Provinces, the distribution patterns of the most important cattle ticks have been relatively unchanged over the past 30 years. The Rhicicephalus sanguineus group was represented by six species. R. camicasi was the only species present on cattle, sheep and goats in the north in Kassala and Khartoum Provinces, whereas this species occurred sympatrically with R. guilhoni and R. turanicus further south in Gezira and Blue Nile Provinces. In the Southern Region of the Sudan only R. turanicus and R. guilhoni were present, the latter being by far the predominant species, with peak activity towards the end of the rains in the Jonglei Canal Area. R. bergeoni was collected once, from cattle near the Ethiopian border in Blue Nile Province, whereas R. sanguineus sensu stricto was collected throughout the study area, from domestic dogs only. Finally, R. sulcatus was found once on a hare. The distributions of the common tick species are correlated with the occurrence of tick-borne diseases of domestic animals and recommendations for the control of tick-borne diseases and their vectors in the Sudan are given.

Animals↗
PubMed1989

Evaluation of the eradication program for Amblyomma variegatum (Acari:Ixodidae) on Puerto Rico.

A cooperative effort between the United States Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, the Agricultural Research Service, and the Department of Agriculture, Commonwealth Government of Puerto Rico has been successful in eradicating Amblyomma variegatum (Fabricius) from the islands of Puerto Rico and Vieques (an island municipality of Puerto Rico). Application of acaricides to livestock and dogs at 14-day intervals for an 18-month period eliminated foci of tick infestation on 188 farms in four different locations without additional aerial or ground treatment. Reasons for the success and some of the costs associated with the eradication program on Puerto Rico are presented.

Animals↗
PubMed1989

Treatment of clothing with a permethrin spray for personal protection against the western black-legged tick, Ixodes pacificus (Acari: Ixodidae).

The synthetic pyrethroid, permethrin, when applied to clothing with a pressurized spray at an application rate estimated previously to be 4 micrograms a.i./cm2, was found to be 100% effective for personal protection against all three parasitic stages of the western black-legged tick, Ixodes pacificus Cooley and Kohls. This tick has been implicated as the primary vector of the Lyme disease spirochete (Borrelia burgdorferi) to humans in the far-western United States. Periods of exposure to permethrin-treated cloth as brief as 10 and 45 seconds incapacitated 100% of subadult and adult ticks, respectively, within 1-3 h post-treatment. Under field conditions, permethrin apparently does not repel questing adult ticks, though 100% of ticks recovered from treated clothing after exposures as brief as less than or equal to 15 seconds were moribund 1 h later.

Aerosols↗
PubMed1990

Gross morphological changes in the salivary glands of Ixodes ricinus (Acari, Ixodidae) between bloodmeals in relation to active uptake of atmospheric water vapour.

The gross morphological changes in the salivary glands of Ixodes ricinus (L.) were investigated at the light microscopic level in various phases off the host with emphasis on the engorged nymph, in order to relate the capability of active vapour uptake in the course of postembryonal development to degeneration and regeneration of salivary-gland alveoli. Agranular alveoli in engorged immatures of I. ricinus, from detachment to the following early pharate phase, do not appear different from those of the unfed instars. This is also true for the female up to approximately the end of oviposition. During moulting, the agranular alveoli of the immatures degenerate and new ones are formed which are apparently already functional in teneral nymphs and adults. In contrast, granular alveoli, much enlarged in freshly detached immature I. ricinus, shrivel in the early post-repletion period and soon reach a highly reduced state which is maintained until apolysis. Subsequently, they disintegrate completely. The finding that engorged and detached immatures of I. ricinus with markedly atrophied granular alveoli are capable of active vapour uptake until some days after initiation of apolysis suggests that only agranular alveoli are responsible for producing the primary secretion involved in vapour uptake.

Animals↗
PubMed1990

Population growth rates for Amblyomma americanum (Acari: Ixodidae) on Bos indicus, B. taurus and B. indicus x B. taurus cattle.

Densities of Amblyomma americanum (L.) on Bos indicus, B. taurus and B. indicus X B. taurus cattle are compared over a 3-year period, and the growth rate (rate of increase or decrease) of parasitic tick populations on each cattle genotype is estimated. Average log10 densities of parasitic A. americanum larvae are significantly (P = 0.05) lower on B. indicus cattle than on B. taurus and B. indicus XB. taurus cattle. Average log densities of nymphal and adult ticks on B. taurus cattle are significantly higher than on B. indicus cattle but neither cattle genotype differs in this regard from B. indicus X B. taurus cattle. Estimated annual tick population growth rates (log10) for parasitic A. americanum are positive on B. taurus cattle (+0.84 larvae, +0.09 nymphs, +0.22 adults calf-1 year-1), but are negative on B. indicus (-0.18 nymphs, -0.14 adults calf-1 year-1) and B. indicus X B. taurus cattle (-0.45 larvae, -0.24 nymphs, -0.14 adults calf-1 year-1). Populations of parasitic larvae were not detected on B. indicus cattle.

Animals↗