The ecology of the free-living stages of Ostertagia circumcincta

Parasitology ◽  
1972 ◽  
Vol 64 (3) ◽  
pp. 451-460 ◽  
Author(s):  
T. E. Gibson ◽  
G. Everett
Keyword(s):  
Development Time ◽  
Grazing Management ◽  
Free Living ◽  
Faecal Output ◽  
Parasitic Gastroenteritis ◽  
Eggs And Larvae

The development and survival of the eggs and larvae of O. circumcincta was studied by spreading the daily faecal output of a sheep over a 2 m square grass plot for 1 week. Observations were carried out for 3 years on material spread at 4-weekly intervals and broadly similar results were obtained in each year. Development time was long in eggs placed outside in January, February, March, November and December. Yields of larvae were small and all were dead within 5 months. During the rest of the year development time was about 2 weeks, yields of larvae were high and larvae survived until July or August of the following year. The significance of these findings in devising systems of grazing management to control parasitic gastroenteritis is discussed.

The ecology of the free-living stages of Trichostrongylus colubriformis

Parasitology ◽  
1967 ◽  
Vol 57 (3) ◽  
pp. 533-547 ◽  
Author(s):  
T. E. Gibson ◽  
G. Everett
Keyword(s):  
Technical Assistance ◽  
Infected Sheep ◽  
Free Living ◽  
Trichostrongylus Colubriformis ◽  
Faecal Output ◽  
Infective Larvae ◽  
June July ◽  
Eggs And Larvae ◽  
Do So ◽  
Favourable Development

The development and survival of the eggs and larvae of T. colubriformis was studied by spreading the daily faecal output of an infected sheep for 1 or 2 weeks on grass plots 6 ft square. The observations were carried out for 3 years and broadly similar results were obtained in each year. Eggs placed on the ground from November to February failed to develop. A large proportion of the eggs placed on the ground in March disintegrate but those which develop do so slowly. Infective larvae are not produced for 8–12 weeks and they are relatively short lived. As conditions become more favourable development becomes more rapid, taking 8 weeks in April 6 weeks in May and only 1 week in June, July and August. A larger proportion of the eggs develop into infective larvae and their time of survival increases. On most plots larvae did not die out until the following April. The prolonged period of snow during the winter of 1962–63 tended to preserve larvae rather than kill them. The relevance of these results to the control of trichostrongylosis is discussed and it is concluded that it would be impossible under British conditions to devise a system of rotational grazing which would satisfactorily control trichostrongylosis and at the same time ensure economic utilization of the herbage.We are grateful to Mr C. R. Phillips and Mr T. Doy for technical assistance during the course of this investigation.

Observations on the free-living stages of the stomach worm Haemonchus contortus

Parasitology ◽  
1963 ◽  
Vol 53 (3-4) ◽  
pp. 469-481 ◽  
Author(s):  
J. H. Rose
Keyword(s):  
Haemonchus Contortus ◽  
Free Living ◽  
Rate Of Development ◽  
Temperature And Humidity ◽  
Survival And Development ◽  
Effects Of Temperature ◽  
Eggs And Larvae ◽  
Heavy Mortality

Outdoor observations were made on the rate of development of the free-living stages of H. contortus at different times of the year, and on the migratory activities and longevity of the larvae in faeces, on herbage and in soil.The effects of temperature and humidity on the survival and development of eggs and larvae, both in faeces and when separated from the faeces, were studied in the laboratory.The results of these observations are discussed in relation to the heavy mortality of the free-living stages of H. contortus and to the transmission of infection in the field.

MORPHOLOGY, DEVELOPMENT, AND BEHAVIOR OF THE IMMATURE STAGES OF THE PARASITE BATHYPLECTES ANURUS (HYMENOPTERA: ICHNEUMONIDAE)

1980 ◽  
Vol 112 (5) ◽  
pp. 481-487 ◽  
Author(s):  
D. P. Bartell ◽  
B. C. Pass
Keyword(s):  
Incubation Period ◽  
Development Time ◽  
Fat Body ◽  
Immature Stages ◽  
Hypera Postica ◽  
Complete Development ◽  
Morphology Development ◽  
And Behavior ◽  
Eggs And Larvae

AbstractObservations, measurements, dissections, and histological preparations were made daily of the eggs and larvae of Bathyplectes anurus (Thomson) while in their host, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae). Observation of development began 24 h after oviposition and ended when parasite larvae emerged from their hosts.Parasite eggs doubled in length and width during their 3- to 4-day incubation period. Parasite larvae fed on hemolymph initially but later instars preferred the fat body and other tissues. B. anurus has five instars. From 18 to 21 days were required for the larvae to complete development and total development time was 21–25 days at 21 ± 1 °C.

Observations on the free-living stages of strongylid nematodes of the horse

Parasitology ◽  
1972 ◽  
Vol 64 (3) ◽  
pp. 461-477 ◽  
Author(s):  
C. P. Ogbourne
Keyword(s):  
Laboratory Experiments ◽  
Field Observations ◽  
Infective Stage ◽  
Free Living ◽  
Rate Of Development ◽  
Infective Larvae ◽  
Strongylus Vulgaris ◽  
Different Temperatures ◽  
Eggs And Larvae

Observations have been made on the development and survival of the free-living stages in faeces deposited out of doors at different times of year, and on the migration of infective larvae to the surrounding herbage. Laboratory experiments were performed to assist in the interpretation of the field observations. Studies were made on the rate of development to the infective stage in faeces kept at different temperatures. The rates at which eggs and larvae of Strongylus vulgaris, S edentatus, S. equinus and Trichonema nassatum developed on faecal-agar cultures at different temperatures were compared. Studies were also made on the effect of desiccation of faeces on the development and survival of the free-living stages. The results of these observations are discussed in relation to the development of herbage infestations on British pastures.

Nematode egg-shells

Parasitology ◽  
1980 ◽  
Vol 81 (2) ◽  
pp. 447-463 ◽  
Author(s):  
David Wharton
Keyword(s):  
High Mortality ◽  
Free Living ◽  
Biotic Potential ◽  
Wastage Rate ◽  
Egg Shells ◽  
Nematode Eggs ◽  
Eggs And Larvae

SUMMARYThe transmission of parasites often involves a high mortality of free-living stages in the environment outside the host. This may be offset by a high biotic potential. In addition, adaptations of nematode eggs and larvae that ensure their survival or increase their chances of infecting a host will reduce the potential wastage rate. Increasing transmission will have an effect equivalent to increasing the fecundity of the parasite and, energetically, may be the more favourable strategy.

The effect of constant and changing temperatures on the development of the eggs and larvae of Oswaldocruzia filiformis (Nematoda: Trichostrongyloidea)

1988 ◽  
Vol 62 (4) ◽  
pp. 281-292 ◽  
Author(s):  
Christine T. Griffin
Keyword(s):  
Room Temperature ◽  
Rana Temporaria ◽  
Free Living ◽  
Temperature Changes ◽  
Larval Stages ◽  
The Third ◽  
Temperature Regimes ◽  
Frog Tadpoles ◽  
Eggs And Larvae ◽  
Duration Of Development

AbstractThe free-living stages of Oswaldocruzia filiformis were cultured in tapwater under constant and changing temperature regimes. Embryonation and hatching proceeded at constant temperatures from 6° to 32°C; development of larvae to the third (infective) stage occurred between 6° and 34°C. The duration of development decreased with increased temperatures up to 28°C. The duration of development of egg and larval stages under changing temperatures was compared with values predicted from constant temperature experiments. The rate of development of eggs to hatching was significantly accelerated under regimes of both sudden and gradual temperature changes. The effect of fluctuating temperatures on larval development was less consistent; both acceleration and retardation effects were recorded. Frog tadpoles (Rana temporaria) were experimentally infected with O. filiformis; early parasitic development proceeded significantly faster at room temperature than at 9–10°C.

THE EFFECTS OF TEMPERATURE AND HUMIDITY ON THE FREE-LIVING STAGES OF TRICHOSTRONGYLUS RETORTAEFORMIS

1959 ◽  
Vol 37 (3) ◽  
pp. 305-316 ◽  
Author(s):  
Devandra Prasad
Keyword(s):  
Infective Stage ◽  
Optimum Temperature ◽  
Free Living ◽  
Infective Larvae ◽  
Faecal Culture ◽  
Temperature And Humidity ◽  
Effects Of Temperature ◽  
Eggs And Larvae

The optimum temperature for development of Trichostrongylus retortaeformis is about 25 °C in a wet faecal culture, when the infective stage is reached in from 3 to 5 days, but at 3 to 5 °C a few larvae can develop in 8 to 10 weeks, and infective larvae can survive for 13 weeks. Both eggs and larvae can survive desiccation for considerable periods.

The ecology of the free-living stages of Ostertagia ostertagi in a winter rainfall region

1981 ◽  
Vol 32 (2) ◽  
pp. 371 ◽  
Author(s):  
RR Young ◽  
N Anderson
Keyword(s):  
Developmental Stages ◽  
Mortality Rates ◽  
Wide Distribution ◽  
Early Spring ◽  
Initial Population ◽  
Free Living ◽  
Infective Larvae ◽  
Cattle Faeces ◽  
Eggs And Larvae ◽  
Rainfall Region

On a series of pasture plots, 500 g pats of cattle faeces containing eggs of the trichostrongylid Ostevtagia ostertagi were deposited at intervals of about 6 weeks from June 1976 to June 1977. The development and survival of eggs and larvae in dung pats and the survival of larvae on surrounding herbage and soil were measured and expressed as a percentage of the initial population of eggs. During summer months comparisons were made between the pats on irrigated and those on non-irrigated plots. Minimum temperatures within dung pats were always greater than those required for development, and infective larvae were recovered from all plots. The onset of development was delayed from 3 to 12 days in summer and from 34 to 68 days in winter, which led to a wide distribution of developmental stages. Rates of development were closely related to the temperatures in soil and dung pats, and mortality rates of pre-infective stages increased very rapidly with increasing temperatures and decreasing moisture levels. Infective larvae were present in abundance on herbage and in soil between 6 and 10 weeks after deposition, provided that the moisture content of these was high. Mortality of these larvae was low during winter and early spring but increased rapidly in mid- to late spring, irrespective of the time of deposition of dung pats. Mortality rates of infective larvae in dung pats deposited in either spring or summer were low and a large proportion of these larvae were capable of moving into herbage and soil after autumn rains. Irrigation during summer did not provide ideal conditions for the development of infective larvae from eggs, but hastened larval migration from dung pats.

The development and overwintering survival of free-living larvae of Haemonchus contortus in Sweden

2005 ◽  
Vol 79 (4) ◽  
pp. 373-379 ◽  
Author(s):  
K. Troell ◽  
P. Waller ◽  
J. Höglund
Keyword(s):  
Haemonchus Contortus ◽  
Practical Significance ◽  
Southern Sweden ◽  
Free Living ◽  
Term Survival ◽  
Commercial Flock ◽  
Long Time ◽  
Overwintering Survival ◽  
Eggs And Larvae

AbstractFive complimentary studies were undertaken with the overall aim to examine the ability of free-living stages of Haemonchus contortus to over-winter and tolerate cold stress. Two studies deal with the development and long-term survival of eggs and infective larvae of two geographically different isolates (Kenya and Sweden). Eggs and larvae were monitored in climatic chambers at temperatures that fluctuated daily between −1°C and 15°C, or at constant temperatures of 5°C and 15°C. The development from egg to larvae was dependent on temperatures over 5°C. The long time survival was favoured at lower temperatures. Furthermore, the overwintering capacity of the free-living stages of these isolates was estimated under Swedish field conditions. Two groups of lambs were experimentally infected with different isolates, and kept separated on previously ungrazed plots. In early May the following year, two parasite-naive tracer lambs were turned out on each of the plots to estimate the pick up of overwintered larvae. This experiment was replicated in central and southern Sweden. In addition, two experiments were performed in 2003 on pasture previously grazed by naturally infected sheep. One trial was on a pasture in southern Sweden grazed by a commercial flock, where extreme numbers of H. contortus were found towards the end of the grazing season 2002. The other study was on a pasture plot in central Sweden grazed by a hobby flock in 2002, where three of six lambs died due to haemonchiasis. Overwintered H. contortus was recorded on three of four experimental sites. Worm burdens were in all instances extremely low. No differences in development and survival were found between the isolates. Consequently, overwintering on pasture is of no practical significance in the transmission of H. contortus between grazing-seasons in Sweden.

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