Development of Tetrapetalonema llewellyni to the Infective Stage in Culicoides hollensis

1982 ◽  
Vol 68 (2) ◽  
pp. 293 ◽  
Author(s):  
Jon A. Yates ◽  
Robert C. Lowrie ◽  
Mark L. Eberhard
Keyword(s):  
Infective Stage

The ecology of immature phases of Trichostrongyle nematodes: II. The effect of climatic factors on the availability of the infective larvae of Trichostrongylus retortaeformis to the host

Parasitology ◽  
1948 ◽  
Vol 39 (1-2) ◽  
pp. 26-38 ◽  
Author(s):  
H. D. Crofton
Keyword(s):  
Climatic Factors ◽  
Faecal Pellet ◽  
Cold Weather ◽  
Maximum Temperature ◽  
Infective Stage ◽  
Faecal Pellets ◽  
Infective Larvae ◽  
High Death ◽  
Maximum Temperatures ◽  
Rate Of Evaporation

1. Eggs and larvae of Trichostrongylus retortaeformis were used.2. The rate of hatching of eggs was shown to be mainly related to temperature. From November to March, when maximum temperatures were below 50° F., there was no hatching. When maximum temperatures of 50–55° F. occurred eggs hatched on or before the fifteenth day, but never during the first 8 days. Eggs hatched in 8 days or less when maximum temperatures of 60–80° F. occurred.3. When the rate of evaporation in the air was high, eggs still hatched and reached the infective stage, the grass blades reducing the rate of loss of moisture from the faecal pellet. Laboratory experiments show that eggs may not develop to the infective stage if the faecal pellets are on a grassless portion of the pasture. This is most likely to occur when the rate of evaporation is high and the temperature low.4. Hatching may be delayed by cold conditions, but some eggs remain viable for long periods and they hatch when the temperature rises. Eggs passed by the host in the autumn can survive a cold winter and hatch in the spring, but eggs passed during the coldest period die.5. During periods when the maximum temperature never exceeded 55° F., little or no migration of larvae occurred. When temperatures rose above 55° F. the number of larvae migrating increased; but rise of temperature was associated with increase in the rate of evaporation. High rates of evaporation reduced the number of larvae migrating on the grass blades.6. Some infective larvae died soon after exposure on grass plots, but a small number survived long periods. In cold weather some larvae were still alive after 20 weeks. A high death-rate occurred in warm weather. A large proportion of the larvae died during periods in which the rate of evaporation was high; in one of these periods 95% of the larvae were dead at the end of 4 weeks' exposure.7. The number of larvae on grass blades of a pasture was shown to be dependent, at any time, upon the climate at that time, and upon past conditions which had influenced hatching and survival:

scholarly journals In vitro evaluation of ivermectin, moxidectin, albendazole and pyrantel against cyathostomins of horses

2017 ◽  
Vol 27 (1) ◽  
pp. 90-93 ◽  
Author(s):  
Marcelo Beltrão Molento ◽  
Ricardo José Canever
Keyword(s):  
Multidrug Resistance ◽  
Drug Monitoring ◽  
Drug Efficacy ◽  
Effective Concentration ◽  
Coefficient Of Determination ◽  
Infective Stage ◽  
Drug Candidates ◽  
Alternative Drug

Abstract Cyathostomins are the most prevalent nematodes of horses, and multidrug resistance has been reported worldwide. There is a need to implement alternative drug monitoring analytical tests. The objective of this study was to determine the consistency (5 repetitions) of the larval migration on agar test (LMAT) using ivermectin, moxidectin, pyrantel or albendazole against cyathostomin infective-stage larvae in eight different concentrations. LMAT showed a strong coefficient of determination (R2 > 0.91), between the test repetitions (n=5). The average 50% effective concentration (EC50) for ivermectin, moxidectin, pyrantel and albendazole were 0.0404, 0.0558, 0.0864 and 0.0988 nMol, respectively. The results of the EC50 for albendazole showed the greatest range of concentration. Ivermectin and moxidectin had the lowest in between-test variation. In the future, internationally certified susceptible isolates could be used for screening new drug candidates, or to follow up the pattern of drug efficacy from field populations.

Some Observations on the biology of the Root-gall Nematode, Anguillulina Radicicola (Greeff, 1872)

1932 ◽  
Vol 10 (1) ◽  
pp. 33-44 ◽  
Author(s):  
T. Goodey
Keyword(s):  
Life History ◽  
Living Condition ◽  
Poa Annua ◽  
Infective Stage ◽  
Northern Sweden ◽  
Important Data ◽  
Set Up

In a paper published in 1925, the writer described the anatomy of the adults of this parasite and amplified Schøyen's account of it. At the same time it was shown that infective material derived from Elymus arenarius could give rise to galls on the roots of barley and Poa annua. Kemner (1930) has quite recently shown experimentally that the parasite from barley can set up galls on E. arenarius and presented important data on the agricultural significance of the parasite in northern Sweden. Detailed information as to which is infective stage of the parasite and on its life-history have so far been lacking and in order to remedy this omission the writer made a number of observations and carried out certain cultural experiments during 1927 and in the months of July, August and September 1931. These latter were made possible by the arrival during July of a good supply of galled roots of Elymus arenarius received in a living condition.

An improved technique for the cryopreservation of Onchocerca microfilariae

Parasitology ◽  
1981 ◽  
Vol 83 (1) ◽  
pp. 139-146 ◽  
Author(s):  
P. J. Ham ◽  
S. Townson ◽  
E. R. James ◽  
A. E. Bianco
Keyword(s):  
Liquid Nitrogen ◽  
Field Conditions ◽  
Insect Vector ◽  
Infective Stage ◽  
Rapid Cooling ◽  
Improved Technique

SUMMARYExperiments describe the use of ethanediol to store Onchocerca microfilariae in liquid nitrogen. The technique involves a 2-stage incubation of the parasites at 37 °C and 0 °C in ethanediol, before rapid cooling to − 196 °C. Viability has been assessed by motility, by migration in a proxy host and by development to the infective stage in the insect vector. A total of 71–79% of the cryopreserved microfilariae was shown to be viable compared to unfrozen controls. The technique is simple, inexpensive and very effective when compared to previous cryopreservation procedures for microfilariae and should be particularly suited for use under field conditions.

Light microscope observations of granulomatous reactions against developing Porocephalus crotali (Pentastomida: Porocephalida) in mouse and rat

Parasitology ◽  
1988 ◽  
Vol 97 (1) ◽  
pp. 27-42 ◽  
Author(s):  
N. C. Ambrose ◽  
J. Riley
Keyword(s):  
Mast Cell ◽  
Adipose Tissue ◽  
Mast Cells ◽  
Plasma Cells ◽  
Ventral Side ◽  
Infective Stage ◽  
Granulomatous Lesion ◽  
Intermediate Hosts ◽  
Epithelioid Cells ◽  
Large Numbers

SUMMARYThe development of granulomatous reactions against moulting nymphal pentastomids (Porocephalus crotali) in the tissues of rat and mouse intermediate hosts is described. Adipose tissue and lungs are favoured sites for encystment accounting for 70% of larvae. Six moults separate the primary larva from the final infective stage which first appears about 80 days post-infection (p.i.) and is fully infective by day 120. Larvae, and particularly their cast cuticles, are the foci of granulomatous reactions characterized by an intense eosinophilia. During ecdysis, large numbers of eosinophils permeate the entire lesion but, significantly, degranulation is limited to the underside of cast cuticles where the resultant debris is endocytosed by macrophage/epithelioid cells. A pronounced asymmetry in the granulomatous lesion, evident even in the earliest cysts, results from the accumulation of individual epithelioid granulomas associated with cuticle fragments close to the ventral side of the developing parasite; each is circumscribed by fibrosis. External to this region are extensive tracts of tissue composed of mature plasma cells. Particularly in rats, large numbers of partially degranulated mast cells ( = globule leucocytes) also surround cuticle granulomas, and mast cell granules can accumulate within macrophages and fibroblasts. Inflammation slowly subsides once the infective stage is attained. This 1 cm-long larva resides in a thin, fibrotic, C-shaped cyst and can remain viable for years: uniquely this instar retains its last moulted cuticle as a protective sheath. Nymphal instars II-VI feed predominantly upon eosinophils but we do not yet know whether this requirement is obligate.

Exsheathment Phenomenon in the Infective-Stage Larvae of Haemonchus contortus

1972 ◽  
Vol 58 (1) ◽  
pp. 34 ◽  
Author(s):  
Nail H. Ozerol ◽  
Paul H. Silverman
Keyword(s):  
Haemonchus Contortus ◽  
Infective Stage

Larval spirurids in a supralittoral amphipod in the north-east of Russia and the identification of the intermediate host of Antechiniella septentrionalis (Spirurida: Acuariidae), parasitic in a tundra vole

2019 ◽  
Vol 94 ◽  
Author(s):  
E.S. Ivanova ◽  
N.E. Dokuchaev ◽  
S.E. Spiridonov
Keyword(s):  
Intermediate Host ◽  
Joint Infection ◽  
Infective Stage ◽  
Magadan Oblast ◽  
Microtus Oeconomus ◽  
North East ◽  
The North ◽  
North Eastern ◽  
Tundra Vole ◽  
Eastern Russia

Abstract The supralittoral amphipod Traskorchestia ditmari (Derzhavin, 1923) was identified as the intermediate host for Antechiniella septentrionalis Ivanova, Dokuchaev & Spiridonov, 2019, a parasite of the tundra vole Microtus oeconomus and Skrjabinocerca sp. (both Spirurida: Acuariidae) in Magadan Oblast in north-eastern Russia. Joint infection by both larval spirurids was not observed. The infective stage of A. septentrionalis was the encysted larvae, while larvae of Skrjabinocerca sp. were free in the amphipod's coelom. The identity of A. septentrionalis was confirmed using cox1 mtDNA gene analysis, performed on adult stages from a tundra vole and on larvae from amphipods. Possible transmission routes of A. septentrionalis are discussed.

Some Observations on the Transmission of Bacteria by Infective Larvae of Nippostrongylus brasiliensis

1955 ◽  
Vol 29 (1-2) ◽  
pp. 27-32 ◽  
Author(s):  
H. M. Gharib
Keyword(s):  
Life Cycle ◽  
Definitive Host ◽  
Infected Host ◽  
Nippostrongylus Brasiliensis ◽  
Infective Stage ◽  
Natural Conditions ◽  
Larval Stages ◽  
Infective Larvae ◽  
External Development

It is well known that the first two larval stages in the life cycle of nematodes belonging to the superfamily Strongloidea, have a freeliving existence. During this time, the larva which hatches from the egg feeds actively, undergoes two moults and grows considerably before reaching the infective stage, when it is ready to invade a definitive host. Under natural conditions this external development takes place in the faeces, which have been deposited by the infected host on ground likely to be contaminated with various bacteria.

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