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At least 163 records · Page 9Linked to original sources
PubMed2004

Morphology of the integumentary structures in the nymph of lace bug, Stephanitis typica (Hemiptera: Tingidae).

The nymphs of the lace bug Stephanitis typica possess unsegmented, slender, integumentary processes. They are arranged chiefly in three rows on the mid-dorsal and lateral sides. The surface ultrastructure of the integumentary process reveals three types of sensilla, namely, companiform sensilla at the tip of the integumentary process having a probable proprioceptive function, oar-shaped wind and gravity sensilla, and pegs supposed to be hygroscopic.

Animals↗
PubMed1995

Immunosuppression and feeding success of Ixodes ricinus nymphs on BALB/c mice.

The effect of repeated infestations of Ixodes ricinus (L.) nymphs on BALB/c mice was studied. Four successive infectations resulted in an increase of tick feeding success. Tick yield and mean engorged weight increased and the length of the feeding period was reduced significantly (P < 0.05-0.01). The increase of specific anti-tick antibodies was not significant (P > 0.05). The blastogenic response of spleen lymphocytes to T-cell mitogens (Con A and PHA-P) was unimpaired or slightly enhanced, whereas the response to B-cell activators (LPS and PWM) was suppressed, as was the total antibody generation in vitro. The numbers of mast cells in murine skin at the tick attachment sites slightly decreased during the third infestation. The suppression of B-cell competence and of antibody generation, together with decrease of skin mast cell numbers in tick attachment sits, are considered to be responsible for enhancement of tick feeding success.

Animals↗
PubMed2005

[Triatoma rubrovaria (Blanchard 1843): life table of nymphs, duration of the forms and posture of the females].

The authors followed the development of 150 eggs of Triatoma rubrovaria to enable the construction of a life table for the nymphs. The winged form was reached by 94.64% of the individuals, of which 79 were males and 65 females. The mean lifetime of the males was 115 days and 99 days for the females. Part of this group was divided into 30 couples and kept separated to facilitate the count of egg laying by each female. Another lot was also formed of 30 males and 30 females but these were housed together in a glass crystallizer that allowed the observation of a larger number of eggs laid (7,832 eggs) in relationship to that of the females with only one male (total 5,167 eggs). The good development of the individuals and reproduction of the species in the experimental conditions demonstrated the capacity to maintain colonies of Triatoma rubrovaria in laboratory conditions.

Animals↗
PubMedDate not supplied

[Biomorphogenetic changes caused by the application of precocene II in nymphs of Triatoma infestans (Klug, 1834) (Hemiptera, Reduviidae, Triatominae)].

The morphogenetic effect of precocene II on 4th instar nymphs of Triatoma infestans was examined. Topical treatment with precocene II (200, 300 and 400 micrograms/nymph) induced the formation of adultoids with the following characteristics: rudimentary wings, three segmented tarsi, ocelli, deformed genitalia and mouth-parts and testes with intermediary development. Precocene II also increases the duration of the molting cycle. The survival of the adultoid insects was related to the inverse of the applied doses. These data extend our knowledge of the action of precocene II on triatominae species.

Animals↗
PubMed2003

Comparative study of the stridulatory sulcus, buccula and rostrum of the nymphs of Triatoma guazu Lent & Wygodzinsky, 1979 and Triatoma jurbergi Carcavallo, Galvão & Lent, 1998 by scanning electron microscopy (Hemiptera, Reduviidae).

The ultrastructural morphology of the ventral region of the head (rostrum and buccula) and proesternum (stridulatory sulcus) of nymphs from the 1st to 5th instars of Triatoma guazu Lent & Wygodzinsky, 1979 and Triatoma jurbergi Carcavallo, Galvão & Lent, 1998 was described. Morphological differences between the two species and of the five nymphal stages development of each species were observed. These structures showed systematic differential characteristics of the studied species and may be used to increase their taxonomic range.

Animals↗
PubMed2003

Development of genital plates in nymphs of Triatoma pallidipennis, Stål 1872, (Hemiptera: Reduviidae) and its application as sexing method.

Searching for morphometric differences between sexes in immature forms, the development of genital plates in the exuviae of Triatoma pallidipennis Stål 1872 nymphs was studied. Differences were found in the form and size of the 9th genital urosternite, it is larger and wider in males as compared to females. This difference is reported in several South American Triatoma species. From our results it is possible to sex early stages from microscopic observation of genital plates in whole insects.

Analysis of Variance↗
PubMed2005

Triatoma rubrovaria (Blanchard, 1843) (Hemiptera-Reduviidae-Triatominae) IV: bionomic aspects on the vector capacity of nymphs.

Triatoma rubrovaria has become the most frequently captured triatomine species since the control of T. infestans in the state of Rio Grande do Sul (RS), Brazil. The aim of this study was to evaluate aspects of the vectorial competence of T. rubrovaria using nymphs raised in laboratory under environmental conditions of temperature and humidity and fed on mice. The average developmental period of T. rubrovaria was 180.1 days. The percentage of defecation shortly after feeding was still higher than previous studies in which samples of T. rubrovaria subjected to a slight starvation period before the blood meal were used. The obtained results support former indication that T. rubrovaria presents bionomic characteristics propitious to be a good vector of Trypanosoma cruzi to man. Therefore its domiciliary invasion process must be continuously monitored.

Animals↗
PubMed2005

[Comparative morphology of eggs and nymphs of Triatoma vandae Carcavallo, Jurberg, Rocha, Galvão, Noireau & Lent, 2002 and Triatoma williami Galvão, Souza & Lima, 1965].

Eggs and all nymphs of these species were studied employing light microscopy (LM) and scanning electron microscopy (SEM). The major differences observed by LM in the eggs were related to the presence and the distribution of pores on the surface of their chorion. Morphological differences among three nymphal stages (1st, 3rd, and 5th) development of each species were observed. The differential characteristics are chromatic and in the shape of connexival spots. The ultrastructure of the ventral region of the head and the IX, X, and XI abdominal segments (anal tube) of the both species were described demonstrating morphological differences that can be used for diagnosis of the species.

Animals↗
PubMed2006

Spatial distribution of nymphs of Scaphoideus titanus (Homoptera: Cicadellidae) in grapes, and evaluation of sequential sampling plans.

The spatial distribution of the nymphs of Scaphoideus titanus Ball (Homoptera Cicadellidae), the vector of grapevine flavescence dorée (Candidatus Phytoplasma vitis, 16Sr-V), was studied by applying Taylor's power law. Studies were conducted from 2002 to 2005, in organic and conventional vineyards of Piedmont, northern Italy. Minimum sample size and fixed precision level stop lines were calculated to develop appropriate sampling plans. Model validation was performed, using independent field data, by means of Resampling Validation of Sample Plans (RVSP) resampling software. The nymphal distribution, analyzed via Taylor's power law, was aggregated, with b = 1.49. A sample of 32 plants was adequate at low pest densities with a precision level of D0 = 0.30; but for a more accurate estimate (D0 = 0.10), the required sample size needs to be 292 plants. Green's fixed precision level stop lines seem to be more suitable for field sampling: RVSP simulations of this sampling plan showed precision levels very close to the desired levels. However, at a prefixed precision level of 0.10, sampling would become too time-consuming, whereas a precision level of 0.25 is easily achievable. How these results could influence the correct application of the compulsory control of S. titanus and Flavescence dorée in Italy is discussed.

Animals↗
PubMed1988

Hepatic granuloma in a man from North America caused by a nymph of Linguatula serrata.

A calcified nodule on the liver of a 62-year-old man from North Carolina, USA, contained a degenerated nymph of Linguatula serrata. The nodule was incidentally discovered at laparotomy for malignant lymphoma and cholelithiasis. The cuticle was all that remained of the parasite, but sclerotized openings and large spines on the cuticle proved the parasite was L. serrata, a pentastomid arthropod. Anatomic location and size of the parasite indicated that it was consistent with the nymphal stage of L. serrata. This is the fifth confirmed infection of humans from North America by a pentastomid parasite.

Animals↗
PubMed2002

[Description of eggs and nymphs of Triatoma jurbergi Carcavallo, Galvão & Lent, 1998 through optical and scanning electron microscopy].

Eggs and nymphs of Triatoma jurbergi were described using optical microscopy and scanning electron microscopy. T. jurbergi is a wild species, found in State of Mato Grosso (15oS and 300 m.a.s.l), Brazil. Eggs showed the operculum and surface with pentagonal and hexagonal cells, with small fractures and punctuations randomly distributed. Differences were found in the five nymphal stages of T. jurbergi, that allow their to be distinguished from the similar species T. guazu. The diagnostic characters most useful for differentiation were the general color of the insect, abdomen shape and its length.

Animals↗
PubMedDate not supplied

[Laboratory study on the immediate and persistent insecticide activity of the pyrethroid lambda-cyhalothrin on nymphs of IV instar Triatoma infestans].

Lambda-cyhalothrin (LCT) is a new broad-spectrum synthetic pyrethroid insecticide with efficient immediate and persistent activity against a great variety of arthropods harmful both to human and animal health and to vegetal production. In many countries this insecticide has been successfully used in the control of infectious diseases vectors, such as mosquitoes, triatomine bugs (transmitters of Trypanosoma cruzi, agent of Chagas' disease) and other arthropods. In order to test the immediate and persistent activity of LCT under laboratory conditions (27 degrees C and 75-80% humidity) on laboratory reared Triatoma infestans--the most resistant instar of this insect to the commonest insecticides used--a series of six experiments was performed in 1-year period. Previous to experiments, the interior surface (400 cm2) of 36 specially manufactured cardboard boxes was uniformly sprayed with 2 ml of the following substrates: 12 with 0.6% LCT suspension, 12 with 1.0% LCT suspension and 12 with water (controls). Twenty four hours, 30 - 90 - 150 - 270 and 360 days later, in two pairs of each six boxes, lots of 10 T. infestans IV nymphs were deposited inside of them. In each of the six experiments, daily observations of the conditions of the insects (unaffected, affected in terms of various grades of progressive uncoordination, or dead) after exposure to the insecticide were performed to end with the register of these conditions 96 hours later. Moreover, after 7 and 10 days of exposure in the immediate and persistent effect of LCT respectively a 100% of mortality was verified.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Morphofunctional changes in the midgut of tick nymphs of the genus Ixodes (Acarina: Ixodidae) during and after feeding].

The midgut epithelium of feeding nymph is represented by the digestive cells of larval phase. Digestion of the main part of feed is performed by the one generation of digestive cells of nymphal phase after detachment, during moult. This period precedes the apolysis. The generation of secretory cells is absent on the nymphal phase. Secretory vacuoles are formed in the digestive cells of larval phase. All functioning cells form a peritrophic matrix on their apical surface. The replacement of the digestive cells of larval phase by the digestive cells of nymphal phase proceeds gradually, during the first 5-10 days after detachment. The beginning of the accumulation of digestive inclusions in the young digestive cells of nymphal phase takes place in the 10-15 days after detachment.

Animals↗
PubMedDate not supplied

[The effect of immersion in distilled water on the engorged larvae and nymphs of Amblyomma dubitatum Neumann, 1899 (Acari: Ixodidae)].

To evaluate the effect of the immersion of engorged larvae and nymphs of Amblyomma dubitatum experimentally fed on rabbits, the ticks were collected and formed control groups, without immersion, and groups witch were immersed by 24, 48, 72, 96 hours and, for engorged larvaes, by eight weeks, in test tubes containing distilled water. During all experiment ticks were kept at 27 +/- 1 degrees C, 80 +/- 10% RU and scotophase The parameters evaluated were: pre-ecdysis, ecdysis and moulting periods; and ecdysis and mortality percentages. When compared with the control group, the effect (p<0,05) of immersion varied intra and inter stages. Apparently, immersion was less deleterious to A. dubitatum in comparison with A. cajennense and R. sanguineus from neotropical region, thus reflecting a long host relations with the capybara, its primary host.

Animals↗
PubMed1990

Estimation of absolute numbers of damselfly nymphs (Odonata: Coenagrionidae) by dipper sampling in California rice fields with seasonal, spatial distributions and vegetation association.

Estimates of relative and absolute density in rice field populations of damselfly nymphs (predominantly Enallagma civile with few Ischnura denticollis) were compared using the regression method. An equation, X = Y divided by 0.0016, allows estimation of absolute density (X) from a relative density index (Y, dipper count). In the rice growing area of Fresno, California, nymphal population peaks appeared during June and August approaching 3-5 million per 0.405 ha (1 acre). Spatial distribution was theoretically represented fairly well by a negative-binomial distribution. The degree of clumping is one of overdispersed types; it is especially classified as a model of randomly distributed colonies with mean colony size fixed. Presence or absence of submerged vegetation markedly affected damselfly nymphal density but the biomass of submerged or emerged vegetation was not a significant factor.

Animals↗
PubMed1990

Intermediate site of development of Anaplasma marginale in feeding adult Dermacentor andersoni ticks that were infected as nymphs.

The development of Anaplasma marginale in midgut epithelial cells was studied in feeding, transmitting adult Dermacentor andersoni ticks. Laboratory-reared ticks experimentally infected as nymphs were allowed to feed from 1 to 9 days on susceptible calves. Gut tissues from ticks were collected on each day they fed (total, 9 days) and were processed for light and transmission electron microscopy. Colonies of A marginale were abundant during the first 6 days of feeding, after which numbers decreased. Colonies were adherent to the basement membrane of gut cells early during feeding, with resultant flattening of the colonies. Colonies also were seen in muscle cells on the hemocoel side of the basement membrane. Morphologic features of A marginale within muscle cells varied and were similar to those observed in gut cells. In addition, however, a large reticulated form in the colonies was observed in muscle cells and appeared to give rise to small particles by budding. Development of A marginale in muscle cells appears to represent an intermediate site of development between those in gut and in salivary glands.

Anaplasma↗
PubMed1979

Descriptions of odonate nymphs from Thailand.

The descriptions of odonate nymphs from Thailand are presented. The insects of the Order Odonata both naiads and adults may serve as the second intermediate host of some intestinal parasites in Thailand.

Animals↗