Sampling Approaches for Extensive Surveys in Nematology

Abstract

Extensive surveys of the frequency and abundance of plant-parasitic nematodes over large geographic areas provide useful data of unknown reliability. Time, cost, and logistical constraints may limit the sampling intensity that can be invested at any survey site. We developed a computer program to evaluate the probability of detection and the reliability of population estimates obtained by different strategies for collecting one sample of 10 cores from a field. We used data from two fields that had been sampled systematically and extensively as the basis for our analyses. Our analyses indicate that, at least for those two fields, it is possible to have a high probability of detecting the presence of nematode species and to reliably estimate abundance, with a single 10-core soil sample from a field. When species were rare or not uniformly distributed in a field, the probability of detection and reliability of the population estimate were correlated with the distance between core removal sites. Increasing the prescribed distance between cores resulted in the composite sample representing a wider range of microenvironments in the field. Key words: abundance, detection, frequency, nematode, plant-parasitic nematode, population density, sampling, survey.