Feeding on different host plants alters the natural abundances of delta C-13 and delta N-15 in Longidoridae (nemata)

Natural abundances of the stable isotope pairs C-13/C-12 (delta(13)C) and N -15/N-14 (delta(15)N) have been used previously to study food sources and t rophic relationships in soil invertebrates. In this study, delta(15)C and d elta(15)N were measured in five species of Longidoridae to investigate the effect of transferring nematodes from one plant host to another. Longidorus elongatus, Paralongidorus maximus, Xiphinema diversicaudatum, IL index, an d X. vuittenezi were cultured initially on Lolium perenne, Pelunia hybrida, Rubus ideaus, Ficus carica, and Rubus ideaus, respectively, and subsequent ly transferred to 4-week-old P. hybrida seedlings. After feeding on P. hybr ida for 28 days, whole body delta(13)C and delta(15)N values of the three X iphinema species were depleted (P = 0.001) and enriched (P = 0.001), respec tively, compared to nematode populations that had fed solely on the origina l plant hosts. Similar changes in L. elongatus and P. maximus whole body de lta(13)C and delta(15)N were not detected. Changes in whole body delta(13)C are considered to be indicative of the new plant host (P, hybrida),whereas differences in whole body delta(15)N are probably related to the different feeding strategies used by the longidorid nematodes in this study.