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PubMed2006

Spatiotemporal patterns of host-seeking Ixodes scapularis nymphs (Acari: Ixodidae) in the United States.

The risk of Lyme disease for humans in the eastern United States is dependent on the density of host-seeking Ixodes scapularis Say nymphal stage ticks infected with Borrelia burgdorferi. Although many local and regional studies have estimated Lyme disease risk using these parameters, this is the first large-scale study using a standardized methodology. Density of host-seeking I. scapularis nymphs was measured by drag sampling of closed canopy deciduous forest habitats in 95 locations spaced among 2 degrees quadrants covering the entire United States east of the 100th meridian. Sampling was done in five standardized transects at each site and repeated three to six times during the summer of 2004. The total number of adults and nymphs of the seven tick species collected was 17,972, with 1,405 nymphal I. scapularis collected in 31 of the 95 sites. Peak global spatial autocorrelation values were found at the smallest lag distance (300 km) and decreased significantly after 1,000 km. Local auto-correlation statistics identified two significant high-density clusters around endemic areas in the northeast and upper Midwest and a low-density cluster in sites south of the 39th parallel, where only 21 nymphs were collected. Peak nymphal host-seeking density occurred earlier in the southern than in the most northern sites. Spatiotemporal density patterns will be combined with Borrelia prevalence data as part of a 4-yr survey to generate a nationwide spatial risk model for I. scapularis-borne Borrelia, which will improve targeting of disease prevention efforts.

Animals↗
PubMed2003

Laboratory studies on the predatory potential of dragon-fly nymphs on mosquito larvae.

Biocontrol potential of dragonfly nymph, Brachythemis contaminata Fabricius against the larvae of Anopheles stephensi, Culex. quinquefasciatus and Aedes aegypti was studied under laboratory conditions. It was found that dragonfly nymph had highest predation efficacy against An. stephensi followed by Cx. quinquefasciatus and Ae. aegypti. Feeding rate increased with decrease in prey size/stage. Analysis of data indicated that dragonfly nymphs have good predatory potential and can be used as a biological control agent for control of mosquito breeding.

Animals↗
PubMedDate not supplied

[In vitro pathogenicity of fungic formulation on nymphs and adults of Rhipicephalus sanguineus (Latreile, 1806) (Acari:Ixodidae)].

Rhipicephalus sanguineus is responsible for transmitting several pathogenic agents, such as: Babesia sp. and Ehrlichia sp.. This species is known as the brown dog tick and has wide geographical distribution. The purpose of this work was to evaluate the pathogenicity of biological formulations of Beauveria bassiana and Metarhizium anisopliae applied to the fed nymphs and adults of R. sanguineus under laboratory conditions. The following treatments were evaluated: control, distilled water with tween 80, emulsible concentrated, cellulose polymerized gel, fungus mixed with emulsible concentrated, fungus mixed with cellulose polymerized gel and fungus mixed with emulsible concentrated and cellulose polymerized gel. Each treatment was repeated ten times. The survival of fed nymphs and unfed adults was evaluated on the 5th, 10th, 15th and the 20th days after treatments. Significant differences were observed between the treatments (p<0.05). The treatment with M. anisopliae mixed with emulsible concentrated and cellulose polymerized gel showed the lower survival on the 15th and 20th days after treatment. We can conclude that the fungi formulation is harmful to fed nymphs and unfed adults of R. sanguineus in vitro, on this account it is suggested its use for the microbial control of this tick.

Animals↗
PubMedDate not supplied

[Study of foveae dorsales of nymphs and adults of four species of ticks (Acari: Ixodidae) by scanning electron microscopy].

The foveae dorsalis, the external opening of the sex pheromone 2,6-dichlorophenol producer gland, of Amblyomma cajennense, Dermacentor nitens, Rhipicephalus (Boophilus) microplus and Rhipicephalus sanguineus was studied with scanning electron microscopy. At least three specimens from each stage: unfed larvae, nymphs, females and males, and females fed for 4 to 6 days were examined. The foveae dorsales were not observed in larvae and R. (B.) microplus males. The foveae dorsales were observed as paired depressions, below the scutum in nymphs and females. In males they appeared as paired subtle elevations, located (2/3) of the way along the idiosoma. Generally the larger structures with a higher number of pores were observed in A. cajennense. Males and nymphs showed foveae dorsales of similar sizes but smaller than those of females. After feeding, secretions were observed in D. nitens and A. cajennense foveae dorsalis. In R. sanguineus and R. (B.) microplus this kind of secretion was not observed. An attempt to connect the appearance of foveae dorsalis with the role of 2,6-dichlorophenol in tick copula has been made. The occurrence of D. nitens females with three foveae dorsales was described.

Animal Structures↗
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.

Animals↗
PubMedDate not supplied

[The photoperiodic regulation of the development and diapause of the nymphs of the taiga tick Ixodes persulcatus (Ixodidae)].

Development and diapause in nymphs of Ixodes persulcatus at the age of 12 months are regulated at 18 degrees C by day-length according to the long-day photoperiodic reaction, and regimens of engorged nymphs are of main importance. Long-day photoperiods (LD 20:4) have stimulated non-diapause development in 97-100% specimens (moulting of 50% nymphs in 67-69 days after feeding), but short-day photoperiods (LD 12:12) have induced diapause (a delay of development over than 6 months) in 75% specimens.

Animals↗
PubMedDate not supplied

[Standards for reviewing preparations in the study of ixodid tick nymphs by dark-field microscopy in borreliosis foci].

The results of dark-field microscopy of 73 positive preparations from the unfed Ixodes persulcatus Sch. nymphs collected in the Perm Region of Russia have been analysed. The preparations were prepared by cutting the ticks placed into a physiological saline drop with needles. The numbers of Borrelia in the preparations varied from 0.4 to 173.6 per 100 microscopic fields (mean 22.9). It has been demonstrated that if all the standard conditions are fulfilled (magnification 600), drop volume 0.005 mil covering 18 x 18 mm glasses), it is practically impossible to overlook an infected nymph while examining 250 microscopic fields in such a preparation. The above-described conditions ensure valid reliable results of Borrelia calculation and their concentration measurements. The differences in the individual Borrelia infection rates in nymphs may be expressed by using the scale: low (up to 10), moderate (10.1-50), and high (above 50 Borrelia per 100 microscopic fields).

Animals↗
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.

Animals↗
PubMed2006

The effect of indoxacarb and five other insecticides on Phytoseiulus persimilis (Acari: Phytoseiidae), Amblyseius fallacis (Acari: Phytoseiidae) and nymphs of Orius insidiosus (Hemiptera: Anthocoridae).

A laboratory study assessed the contact toxicity of indoxacarb, abamectin, endosulfan, insecticidal soap, S-kinoprene and dimethoate to Amblyseius fallacis (Garman), Phytoseiulus persimilis Athias-Henriot and nymphs of Orius insidiosus (Say). Amblyseius fallacis is a predacious phytoseiid mite and an integral part of integrated pest management (IPM) programmes in North American apple orchards. The other two beneficials are widely used in greenhouses to manage various arthropod pests infesting vegetable and ornamental crops. Indoxacarb is a slow-acting insecticide, so toxicity data were recorded 7 days post-treatment when the data had stabilised. It showed no toxicity to O. insidiosus nymphs or to A. fallacis or P. persimilis adults. The LC50 values for O. insidiosus nymphs and P. persimilis could not be estimated with their associated confidence limits, because the g values were greater than 0.5 and under such circumstances the lethal concentration would lie outside the limits. The LC50 for A. fallacis was 7.6x the label rate. The fecundity of P. persimilis was reduced by 26.7%. The eclosion of treated eggs from both species of beneficial mites was not affected adversely. Among the other pest control products, S-kinoprene and endosulfan affected adversely at least one species of the predators, whereas dimethoate, abamectin and insecticidal soap were very toxic to all three beneficials. Indoxacarb should be evaluated as a pest control product in IPM programmes.

Animals↗
PubMed2000

Provisioned Parastrachia japonensis (Hemiptera: Cydnidae) nymphs gain access to food and protection from predators.

Females of the shield bug Parastrachia japonensis Scott progressively provision nymph-containing nests with drupes of the host tree, Schoepfia jasminodora (Olicaceae: Rosidae: Santales). The majority of nests are 5-15 m from the host tree, a distance thought to have been a major impetus for the occurrence of provisioning in this species. However, the function of provisioning is not well understood. We carried out two field experiments to determine whether provisioning is nutritionally important and whether it affords protection against predation. Development of nymphs was significantly delayed and their survival was low in the absence of provisioning, even when nests were within the area of ground on to which the drupes fell, apparently because of the poor quality of the majority of the drupes. Selective provisioning of good-quality drupes by female P. japonensis, a semelparous species, was thus necessary for young nymphs to obtain enough food for their development. Furthermore, even without a female in attendance, having drupes in the nest significantly reduced early mortality in the presence of a predator. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Effects of Temperature and Exposure Duration on Transfer of Cadmium Between Naturally Contaminated Sediments and Burrowing Mayfly Nymphs (Hexagenia rigida)

Burrowing mayfly nymphs (Hexagenia rigida) were exposed to naturally contaminated sediments collected from two stations along a metallic pollution gradient on the Lot River (France) using indoor microcosms. Bioaccumulation kinetics (0, 20, 40, and 60 days) of cadmium (Cd) and the combined effects of temperature (12, 18, and 24 degreesC) were evaluated by a complete experimental design, jointly with the analysis of growth rate of the nymphs, bioturbation, and total and dissolved Cd concentrations in the water column. Cadmium was transferred from the sediment to the organisms with uptake influenced by contamination levels of the sediments, exposure duration, and temperature. The two complementary criteria-Cd concentration and burden in the nymphs-clearly demonstrate the importance of the growth dilution on the quantification of Cd bioaccumulation at the whole organism level.

Journal Article↗
PubMed1999

Influence of the genetic background and parasite load of mice on the immune response developed against nymphs of Ixodes ricinus.

The immune response of BALB/c (H-2d), DBA (H-2d), C57BL/6 (H-2b), C3H (H-2k), CBA (H-2k), SJL (H-2s), and FVB (H-2q) mice infested once with 15 nymphs of Ixodes ricinus is polarized toward Th2 as suggested by cytokines produced by lymph node cells stimulated with concanavalin A. The parasite load does not influence the polarization of the immune response as observed in BALB/c mice, which developed a Th2 response when infested with 5 or 45 nymphs. As assessed by attachment and weights of engorged nymphs, no resistance was acquired by BALB/c, C57BL/6, or C3H mice undergoing three successive infestations. However, these mice produced a gradual increase in IgE.

Animals↗
PubMed2003

Nymphs of the Oriental cockroach (Blatta orientalis) as passive vectors of causal agents of avian tuberculosis and paratuberculosis.

The potential transmission of the causal agent of paratuberculosis Mycobacterium avium ssp. paratuberculosis and avian tuberculosis Mycobacterium avium ssp. avium (Actinomycetales: Mycobacteriaceae) by nymphs of the Oriental cockroach Blatta orientalis L. (Blattodea: Blattidae) was investigated by oral infection with mycobacterial suspensions and examination of their droppings and bodies. Both the subspecies of M. avium were isolated from droppings at 3 days post-infection and M. a. avium was found in homogenized bodies at 10 days post-infection. The identity of M. a. avium and M. a. paratuberculosis isolates was demonstrated by Restriction Fragment Length Polymorphism (RFLP) analysis. The M. a. avium isolate used as the inoculum and the isolates from the bodies and droppings of the nymphs were shown to be virulent in chickens. The results show that orally infected nymphs of B. orientalis can harbour and shed viable and virulent mycobacteria. This hazard should be considered in the implementation of control measures against mycobacterial infections of animals and humans, which should include destruction of all developmental stages of cockroaches and prevention of their access to materials that can be contaminated by mycobacteria.

Animals↗
PubMed2005

Parasitism of Lygus spp. nymphs by the parasitoid wasp, Peristenus howardi, in the alfalfa seed-growing region of the Pacific Northwest.

The parasitoid, Peristenus howardi Shaw (Hymenoptera: Braconidae) has been found to parasitize a large proportion of Lygus species in some Washington and Idaho alfalfa seed fields. During 2002-2003 a survey was conducted to estimate the proportion of Lygus spp. (Hemiptera: Miridae) parasitized and the amountof that parasitism attributable to P. howardi in crop and non-crop plants attacked by Lygus in the alfalfa seed growing region of southwestern Idaho and eastern Oregon. Percentage parasitism was estimated from dissection of field-collected Lygus nymphs. Polymerase chain reaction (PCR) was used to amplify DNA extracted from parasitoid larvae followed by restriction endonuclease digestion of PCR products to distinguish P. howardi from other potentially co-occurring Peristenus species. Peak parasitism of Lygus nymphs occurred between the first and third weeks of July for both years for all host plants sampled. Of the parasitoid larvae recovered from Lygus nymphs in our study, 75% to 80% tested positive as Peristenus spp. and 76% of these matched the endonuclease digestion banding pattern for P. howardi. The identity of the remaining 20% to 25% of the parasitoids is not known.

Animals↗
PubMed1994

Suppression of Ixodes scapularis (Acari: Ixodidae) nymphs in a large residential community.

To determine the feasibility of suppressing Ixodes scapularis Say populations in a large, hyperendemic residential community, several rates of granular carbaryl were applied by ground and air to the shrub layer and wooded buffers of a forested residential community during the peak activity period of nymphs. Granular carbaryl significantly reduced the abundance of I. scapularis nymphs on Peromyscus leucopus Raphinesque. Control nymphal ticks ranged between 70.0 and 90.3%. The use of properly timed acaricide applications to I. scapularis habitat within residential communities can provide an effective means of reducing exposure to I. scapularis nymphs, which are chiefly responsible for transmitting Borrelia burgdorferi to humans.

Animals↗
PubMed2000

Methodology for sampling questing nymphs of Ixodes ricinus (Acari: Ixodidae), the principal vector of Lyme disease in Europe.

To assess the Lyme borreliosis vector population density we set up a methodology for sampling the Ixodes ricinus L. population host questing on the vegetation. We focused on the collection of the nymphal stage, which is the principal stage of disease transmission to humans. This study was carried out in Rambouillet forest (Yvelines, France) where seven study areas were demarcated. These areas are maximally homogeneous for plant species using a finer scale than the phytosociological classification as defined by the method of landscape diagnostics. Out of 23 collections performed from March 1997 to May 1998, 2,906 I. ricinus nymphs were collected. The sampling technique chosen was the cloth lure technique. The technical parameters were studied and fixed (cloth type, cloth size, sample size, researcher position). It appeared that toweling was the best cloth type to optimize the number of ticks collected; the position of the researcher had no effect on tick samples. To satisfy the criteria for correct sampling, we studied representativity, randomness, and nonselectivity of our methodology. The spatial distribution of nymphs in a homogeneous area was close to random and thus very few subsamples were needed to obtain a relative density which was representative. No significant differences were found between random samples and following transect samples; and nonselectivity was totally satisfied because we only worked on questing nymphs. We grouped the samples that presented no significant differences to attribute a density index, which varied from 0 to 5. This methodology, applied with the same parameters, offers potential for producing comparable results from studies in different geographical areas and at different times of the years.

Animals↗
PubMed1997

Infestation with pathogen-free nymphs of the tick Ixodes scapularis induces host resistance to transmission of Borrelia burgdorferi by ticks.

Female BALB/c mice were infested four times with pathogen-free Ixodes scapularis nymphs prior to infestation with nymphs infected with Borrelia burgdorferi B31. Each infestation was separated by a 14-day tick-free period. Mean weights of fed ticks and percentage reaching repletion did not indicate development of acquired resistance. Only 16.7% of mice repeatedly infested with pathogen-free ticks prior to infected I. scapularis nymph challenge became positive for B. burgdorferi. One hundred percent of control mice infested only with infected ticks were culture positive for B. burgdorferi.

Animals↗
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.

Animals↗