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PubMedDate not supplied

[Ultrastructure of the epithelium of the midgut in nymphs of Hyalomma asiaticum (Acarina, Ixodidae) ticks during feeding].

The midgut epithelium of H. asiaticum nymphs was studied by means of electron microscopy. It has been shown that during feeding the midgut epithelium of the above nymphs consists of three types of cells: reserve, secretory and digestive ones. There have been revealed two types of the digestive cells. The cells of the first type are capable for two forms of blood endocytosis: phagocytosis and pinocytosis. During feeding in these cells takes place fast intracellular digestion. This type of cells dominates at the beginning of feeding. The second type of digestive cells prevailing at the end of feeding is represented by specialized cells consuming only haemoglobin. A certain part of these cells preserves for a long time an intracellular reserve of haemoglobin.

Animals↗
PubMed1980

Relationship between gill Na+,K+-activated ATPase activity and osmotic stress in the plecopteran nymph, Paragnetina media.

A relationship between osmotic stress and gill Na+,K+-activated ATPase was observed in plecopteran nymphs acclimated to diluted creek water and a hypertonic medium. An increase of 84% in diluted creek water is presumably related to an active uptake of sodium ions from the hypotonic medium. Whereas a 21% decrease in the enzyme activity may be related to the morphological changes in the specialized cells in the gills. The Na+,K+-activated ATPase activity was also compared with the Malpighian tubules and the rectum. The highest ATPase activity of 32.6 +/- 2 mumoles Pi mg protein-1 30 min-1 was observed in the Malpighian tubules. The activity in the gills (19 +/- 1.2 mumoles Pi mg-1 30 min-1) was slightly lower than the rectum. Since the ATPase activity in the gills is quite high, the gills can be considered to play an active role in hyperosmotic regulation in plecopteran nymphs.

Animals↗
PubMed2001

Behavioral response of fifth instar nymphs of Triatoma infestans (Hemiptera: Reduviidae) to pyrethroids.

The hyperactivity (an increase in locomotor activity) and repellency produced by eight pyrethroids, applied as films on filter paper, were evaluated on fifth instar nymphs of Triatoma infestans (Hemiptera: Reduviidae) using a video tracking technique. All the pyrethroids studied produced hyperactivity. As a trend, hyperactivity produced by cyanopyrethroids was higher than that produced by non-cyanopyrethroids. Hyperactivity was not observed when nymphs were pretreated with the sulphydryl reagent N-ethylmaleimide before exposure to the pyrethroids. The eight pyrethroids failed to produce repellency. No repellency was also observed for the flowable formulation of deltamethrin at the concentration recommended for T. infestans control.

Animals↗
PubMed1996

The Marrara syndrome: a hypersensitivity reaction of the upper respiratory tract and buccopharyngeal mucosa to nymphs of Linguatula serrata.

The Marrara syndrome, like Halazoun in Lebanon, is a hypersensitivity reaction of the upper respiratory tract and buccopharyngeal mucosa to nymphs of Linguatula serrata. The condition follows the consumption of Marrara which consists of raw liver, lungs, trachea and rumen of goats and sheep infected with larvae of L. serrata. The adult worm is found in the nasal passages of dogs. Sheep and goats are infected by eggs from infected dogs. A survey that included 240 adult individuals in a village of endemic L. serrata infection in the Sudan showed that 20% experienced symptoms of allergic nasopharyngitis (Marrara syndrome) following the consumption of raw viscera of goats or sheep at least once in their life. In a prospective study of 24 patients who reported to hospital with the Marrara syndrome, the clinical features included itching in the throat and nose, unilateral conductive deafness, tinnitus and facial palsy. Secondary bacterial infection caused suppurative otitis media. Adult L. serrata parasites were found in the nasal passages of 56 and 47% of male and female dogs in the endemic area. Nymphs were recovered from the mesenteric lymph nodes, lungs and livers of goats in the area.

Adult↗
PubMed2002

Temperature acclimation in overwintering nymphs of a cockroach, Periplaneta japonica: walking on ice.

Nymphs of the Yamato cockroach, Periplaneta japonica, showed a seasonal change in the ability to move at low temperature. Laboratory-reared nymphs buried in ice for 15 min-3 h took about 600 s to get up at 25 degrees C after being placed with their dorsal surface on the floor of a Petri dish. The mean time to get up at 25 degrees C (recovering time) after 15 or 60-min burial in ice was relatively long in early autumn, decreased rapidly in autumn, reached a minimal level in winter (<100 s) and increased in spring. Temperature was responsible for this seasonal change in physiology, and neither photoperiod nor diapause status was important. Recovering time depended on the acclimation temperature and its duration. For a 10-day exposure in a range of 0-25 degrees C, the lower the temperature the shorter the recovering. Longer periods of acclimation at these temperatures tended to shorten recovering time. The acquisition of the ability to move on ice is a seasonal phenomenon unique to P. japonica. No comparable response was found in three other cockroaches including two sub-tropical species (Periplaneta americana and Opisthoplatia orientalis) and a temperate species (Blattela nipponica).

Journal Article↗
PubMed1999

Aggregation density and longevity correlate with humidity in first-instar nymphs of the cockroach (Blattella germanica L., Dictyoptera).

Nymphs and adults of the German cockroach, Blattella germanica, tend to aggregate. The effect of six different relative humidities (RH) on the aggregation behaviour of groups of 30 first instars was tested. The results show that grouping is denser under lower RHs than under higher humidities. The mean interindividual distances (nearest neighbour distances) proved to be inversely proportional to saturation deficiency (SD). The effect of aggregation behaviour in regulating water loss by evaporation is discussed. Under deprivation of food and drinking water survival times of the nymphs depend on RH. For five humidity levels tested the longevity (defined as MT(50)) proved to be inversely proportional to SD. The correlation is best fitted by a hyperbola.

Journal Article↗
PubMed2000

Permethrin resistance ratios compared by two methods of testing nymphs of the German cockroach, Blattella germanica.

For the German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae), the permethrin resistance ratio (RR) was assessed by topical application and by tarsal contact tests, using first-instar nymphs of five strains from Tehran, Iran. Each test was replicated three or four times with 10 nymphs aged 2-3 days; mortality was scored 24h post-treatment. The reference susceptible strain showed LD50 permethrin 0.0175 microl/nymph from topical application, KT50 of 8.41 min and LT50 of 12.82 following tarsal contact with permethrin 15 mg/m2. In four wild strains (F1 generation) the RR varied from 4.14 to 4.7 for mortality after topical application, from 4.2 to 6.45 for mortality and 17-27 for knockdown following tarsal contact tests. Hence, overall knockdown results gave much higher RRs than for mortality data. Resistance ratios based on both methods of treatment were very similar: one strain showed a slightly higher value by topical application (RR 4.6 vs. 4.2, i.e. 1.1-fold difference) whereas the other three strains gave slightly greater RR (1.2-1.4 fold) by tarsal contact. Resistance was abolished by cotreatment with the synergist piperonyl butoxide plus permethrin (ratio 3:1 required for full efficacy), indicating that mixed-function oxidases were inhibited as a major metabolic pathway in all four resistant strains.

Animals↗
PubMed1970

Symbiosis between Euglena and damselfly nymphs is seasonal.

An endosymbiotic association has been demonstrated between Euglena and nymphs of three species of damselfly. The hindgut of the nymphs is inhabited by the euglenoid only during the winter. Symbiotic associations involving green euglenoids and insects are virtually unknown.

Animals↗
PubMed2004

Babesia bigemina: sporozoite isolation from Boophilus microplus nymphs and initial immunomolecular characterization.

It has been hypothesized that babesial sporozoites express specific antigens that induce protective immunologic responses in cattle. However, they remain uncharacterized, partly for lack of research on the sporozoite stage of Babesia spp. This field suffers from complete knowledge of parasite development in the tick salivary gland; limited amounts of sporozoites from ticks, and a lack of protocols for induction and purification of sporozoites. In this work, Boophilus microplus larvae infected with B. bigemina were fed on susceptible cattle. Nymphs were collected and macerates were separated by a Percoll density gradient. Microscopic analysis of Giemsa-stained smears showed a larger number of sporozoites from nymphs fed for 9 days. Percoll-purified sporozoites were observed in large numbers in groups or individually and free of tick cells. RT-PCR analysis of total RNA extracted from purified sporozoites indicated transcription of the rhoptry associate protein 1 (rap-1) genes: rap-1a, rap-b, rap-1c, as well as the heat shock protein 20 (hsp-20) gene. Purified sporozoites were cultured in vitro analyzed for RAP-1a expression using an immunocytochemistry assay. Erythrocyte-attached sporozoites reacted with a specific RAP-1a monoclonal antibody. This is the first report of Babesia bigemina sporozoite antigens. Moreover, purified sporozoites will allow the characterization of stage-specific antigens involved in immunologic protection.

Animals↗
PubMedDate not supplied

[Morphogenetic effects of precocene II on nymphs of Rhodnius prolixus (Stal, 1859) (Hemiptera-Triatominae)].

The morphogenetic effects of Precocene II in nymphs of 1st-, 2nd-, 3rd-, and 4th-instar of Rhodnius prolixus were studied. A high number of insects underwent precocious metamorphosis by topical treatment (10-30 micrograms/insect) or adding the drug to the blood meal (25 micrograms/ml of blood). Adultoids of 4th- and 5th-instar, obtained by both treatments of 3rd- and 4th-instar, respectively, had mainly fully adult abdominal cuticle, ocelli, three segmented tarsi, rudimentary wings containing adult articulation with the thorax and deformed genitalia while adultiforms of 2nd- and 3rd-instar had very slight imaginal morphological characteristics. Topical treatment induced a high mortality in nymphs of 1st-instar and Precocene II given orally produced a high number of adultoids in this instar. The mode of application and the action of Precocene II on different nymphal instars were interpreted.

Animals↗
PubMed2000

Effects of granular carbaryl application on sympatric populations of Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) nymphs.

A single application of granular carbaryl approaching the lowest recommended rate to the shrub layer of a forested area in late spring significantly reduced the abundance of Ixodes scapularis Say nymphs throughout their peak activity period, but had little effect on Amblyomma americanum L. nymphs. Factors influencing the efficacy of the application are discussed. The possible explanations for the lack of efficacy of granular carbaryl against A. americanum, including behavior, formulation, and application rate, are discussed.

Analysis of Variance↗
PubMed2001

Efficacy of granular deltamethrin against Ixodes scapularis and Amblyomma americanum (Acari: Ixodidade) nymphs.

A single barrier application of granular deltamethrin to the woodland edges of a forested residential community in late spring significantly reduced the abundance of Ixodes scapularis Say nymphs. The application also suppressed the population of Amblyomma americanum (L.) nymphs, which recently became established in the study area. The efficacy of deltamethrin is compared with other commonly used acaricides.

Animals↗
PubMed2003

Meteorologically mediated diurnal questing of Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) nymphs.

Questing Ixodes scapularis Say and Amblyomma americanum (L.) nymphs were collected in the field by drag sampling to determine whether ticks would be collected in greater numbers during certain times of the day and under certain ambient meteorological conditions. Ticks were collected hourly for 16 h on 4 d and counts were contrasted with simultaneous measurements of ambient temperature and relative humidity, and with similar measurements made within the leaf litter. Peak numbers of questing I. scapularis and A. americanum nymphs were collected at distinctly different times of day, suggesting that the two species were responding to different environmental conditions. Both species demonstrated responses to diel changes in local meteorological conditions. Numbers of ticks were correlated with ambient temperature and humidity and with conditions recorded in the leaf litter that appeared to play a significant role in mediating questing behavior of both species. The time of day when tick sampling is conducted might significantly bias population estimates for sympatric species and the assessment of tick-borne disease transmission risk.

Animals↗
PubMed2003

Morphological and populational characteristics of hemocytes of Ornithodoros moubata nymphs during the ecdysial phase.

The ultrastructure and characteristics of hemocytes of argasid tick species, Ornithodoros moubata, during the ecdysdial phase are herein presented. Hemocyte classes/populations characterized based on their affinity with Giemsa stain and ultrastructural differences comprised the prohemocytes, nongranular cells (Nc), eosinophilic granular cells (Ec), basophilic granular cells (Bc), and unidentified cells. Significant changes/shift in the ratio of hemocyte classes/population was apparent in ticks before and after the ecdysial phase. The granule-scant basophilic granular cells (sBc) constituted the most abundant hemocyte population in the ecdysial phase. Nymphs in ecdysis showed increases in Nc and sBc and decrease in Ec, a phenomenon that was reversed in unengorged nymphs and adults ticks. The significant increase in total Bc population in ecdysis relative to nonengorged ticks clearly point to blastogenesis of Bc taking place during the ecdysial phase and Bc's important role in the process of tissue remodeling.

Animals↗
PubMed2001

Nymphs of the western black-legged tick (Ixodes pacificus) collected from tree trunks in woodland-grass habitat.

Nymphs of the western black-legged tick, Ixodes pacificus, were found on the trunks of trees during spring and summer in northwestern California. In a woodland-grass habitat, large- and medium-sized (> 130 cm and 80-130 cm in circumference, respectively), moss-covered oak (Quercus spp.) trees supported ticks significantly more often than trees without these characteristics. Additionally, trees with basal leaf-litter and lacking shade (at time of sampling) were significantly associated with the presence of ticks. Mean tick-burdens were > 1 for all oaks (1.06), all trees with basal leaf-litter (1.05), and all trees of large-circumference (1.19); 0.79 ticks per tree were collected over the entire study. Moss reduced the surface temperature of trees by a mean of 1.9 degrees C (range of 1.6-5.0 degrees C) and increased relative humidity by up to 2.5% from the ambient. These microclimatic changes, along with the presence of refugia in bark and western fence lizard (Sceloporus occidentalis) hosts on the lower-most surface of trees, likely accounted for ticks questing on the trunks. Although of undetermined epidemiological significance, the presence of host-seeking I. pacificus nymphs on tree trunks may shed light on the relation of abiotic and biotic factors to the life history of this important vector of disease.

Animals↗
PubMed1981

[Isolation of Babesia microti (França 1912) from free-living nymphs of Ixodes ricinus (Linnaeus 1758) (author's transl)].

375 unfed nymphs of Ixodes ricinus were collected in a natural focus of Babesia microti near Hannover and were tested for an infection with B. microti using golden hamsters (Mesocricetus auratus). 2 strains (Hannover II and Hannover III) were isolated. The incidence of infected nymphs in April 1980 demonstrates the ability of B. microti to hibernate in I. ricinus under natural conditions.

Animals↗
PubMed1975

[Light microscopic studies on the development of Theileria annulata (Dschunkowsky and Luhs, 1904) in Hyalomma anatolicum excavatum (Koch, 1844). I. The development in the gut of engorged nymphs (author's transl)].

A laboratory strain of H. a. excavatum was selected on high susceptibility for T. annulata through several generations. Giemsa-stained smears and wet smears of gut and gut content were studied. After engorgement of erythrocytic stages of T. annulata by the nymphs the following development was observed: 1. Erythrocytic merozoites developed to slender, spindleshaped "microgamonts" in the gut 24 to 96 hours after repletion (p. repl.). Spherical stages with a conspicuous spike developed at the same time and earlier. The "microgamonts" then form up to 4 nuclei and several flagella-like appendices. Filiform "microgametes" obviously develop from the "microgamonts". In addition, spherical stages, i.e. "macrogametes", occur. 2. Spherical "zygotes" with a vacuole-like center appear in the epithelial cells of the gut from day 5 p. repl. These "zygotes" increase steadily in size and then stain more intensely up to day 12 p. repl. 3. From day 12 p. repl. the spherical "Zygotes" change to elongate forms by a continuing process of folding. Finally, from day 13 p. repl., they extend to clubshaped kinetes. These kinetes move actively by gliding within the gut cells and from day 17 p. repl. in the haemolymph. It could not be decided yet whether these kinetes are oo- or sporokinetes.

Animals↗