Effect of agricultural management on nematode communities in a mediterranean agroecosystem.

The effects of agricultural management on the soil nematode community were investigated in a field study at depths of 0 to 10 cm and 10 to 20 cm during a peanut (Arachis hypogaea) growing season in Israel. Nineteen nematode families and 23 genera were observed. Rhabditidae, Cephalobus, Eucephalobus, Aphelenchus, Aphelenchoides, Tetylenchus, Tylenchus, Dorylaimus, and Discolaimus were the dominant family and genera. Ecological measures of soil nematode community structure, diversity, and maturity indices were assessed and compared between the managed (by fertilization, irrigation, and pesticide application) and unmanaged fields. The total number of nematodes at a 10-cm depth during peanut-sowing, mid-season, and harvest periods was higher in the treated (managed) plot than in the control (unmanaged) plot. Bacterivores and fungivores were the most abundant trophic groups in both plots and both depths. The relative abundance of each group averaged 60.8 to 67.3% and 11.5 to 19.6% of the nematode community, respectively. Plant parasites and omnivores-predators at the 0 to 10-cm depth were much less abundant than any other two groups in our experimental plots. During the growing season, except the harvest period, populations of plant parasites and omnivores-predators at the 10 to 20-cm depth were lower in the treated plot than in the control plot. Maturity index (MI), plant-parasite index (PPI), and ratio of fungivores and bacterivores to plant parasites (WI) were found to be more sensitive indicators than other ecological indices for assessing the response of nematode communities to agricultural management in an Israeli agroecosystem.