The Occurrence and Distribution of Species of Xiphinema and Longidorus in Israel 1)

Abstract

Ten species of Xiphinema (X. brevicolle, X. diversicaudatum, X. elongatum, X. index, X. ingens, X. insigne, X. italiae, X. mediterraneum, X. pini and X. turcicum) and six species of Longidorus (L. africanus, L. brevicaudatus, L. laevicapitatus, L. taniwha, L. vineacola and Longidorus sp.), their regional distribution, nature habitats and relative frequency of occurrence in cultivated fields, are reported from Israel. Males of X. brevicolle and X. insigne, hitherto unknown, are described and additional data on the male of X. mediterraneum are presented. Vertical distribution studies on seven species of Xiphinema and two species of Longidorus revealed maximum population levels of all species in the 0-30 cm layer, with a decrease in numbers with increasing depth. Proportions of adult females in relation to larval stages, studied on three ubiquitous species of Xiphinema, were found to increase with increasing depth. No consistent or characteristic pattern in seasonal fluctuations could be discerned in total field populations of any of the species studied; however, a peak in the proportion of adults was observed in most species during the summer months of May-July. A constant relationship was found between the occurrence of the ubiquitous and apparently polyphagous nematode species and soil type. X. mediterraneum, the smallest species identified, was predominant in clayey and poorly aerated soils; most other species prevailed in lighter soils, their relative population sizes increasing in these soils in an almost direct relationship to their volumes.