Predicting populations of Trichostrongylus colubriformis infective larvae on pasture from meteorological data
Barnes, E.H., Dobson, R.J., Donald, A.D. and Waller, P.J. (1988) Predicting populations of Trichostrongylus colubriformis infective larvae on pasture from meteorological data. International Journal for Parasitology, 18 (6). pp. 767-774.
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A long-term field study was carried out at Badgery's Creek, New South Wales, Australia to investigate the ecology of the free-living stages of Trichostrongylus colubriformis. Results included weekly estimates of the number of infective larvae on pasture arising from single applications of contaminated faeces. These were used to construct a mathematical model to predict larval availability on pasture from standard meteorological measurements.
The model has three components predicted from meteorological variables—p, the probability that an egg develops to infective larval stage and migrates to the herbage, E(X1), the average time that the egg takes to develop to infective larval stage and migrate to the herbage, and E(X2), the average lifetime of an infective larva on the herbage. The meteorological variables used to predict p were evaporation and rainfall in the first 2 days after the eggs were deposited on pasture, and the length of time until an effective fall of rain. E(X1) was described by a function of the average temperature in the first week after eggs were deposited on pasture and the length of time until an effective fall of rain. E(X2) was predicted by the rainfall and average temperature in weeks 7–10 after the eggs were deposited on pasture.
A value of R2 = 0.39 was obtained over a set of 39 plots. The optimal value for this set of data is R2 = 0.76. The model was adjusted to simulate the pattern of larval availability on pasture arising from continual contamination by grazing sheep with naturally acquired infections. This gave a value of R2 = 0.60 when tested against published larval availability data obtained in grazing experiments.
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|Copyright:||© 1988 Published by Elsevier Ltd|
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