Influence of interspecific competition on the population dynamics of migratory plant-parasitic nematodes with r and K survival strategies

Abstract

SUMMARY Samples taken over a five year period at a field site in which the dominant plant-parasitic nematode species were Rotylenchzls robustus, Trichodorus primnitivus and ParatricRodorus.pachydemzus indicated that the nematodes had IZ survival strategies. They had relatively low rates of multiplication and their numbers showed no obvious seasonal cycling. In soil where their numbers had been greatly reduced following treatment with the fumigant dichloropropene, numbers of a fourth species Paratylenchus nanus, initially present in small numbers, rapidly increased. This species had an r survival strategy, its numbers increasing rapidly in the absence of competition and also showing marked seasonal fluctuations. In non-fumigated soil P. nanus numbers remained low, probably due to interspecific competition, especially with R. robustus.