GLASS-HOUSE AND LABORATORY STUDIES ON BIOLOGY OF NEEDLE NEMATODE LONGIDORUS ELONGATUS

Thirty-one plant species belonging to eleven botanical families were tested as possible hosts of L. elongatus. They included plants suspected as favourable for reproduction of the nematode, those which are known to be mainly infected with tomato black ring or raspberry ringspot viruses, or those immune to infection, and those used as virus assay plants or 'bait' plants to detect the presence of virus in the soil. There was, however, little connection between ability to support L. elongatus and susceptibility to the viruses it transmits. Strawberry, Fragaria vesca, was among the best hosts. F. vesca was subsequently used to study the life cycle of the nematode. The hatching time of L. elongatus eggs reported here (9-12 days) agrees closely with that in most other plant parasitic nematodes reported by various investigators. On the other hand, the rate of multiplication of L. elongatus found in this investigation was low compared with that in the closely related species, Xiphinema index, studied by other investigators. Thus, while L. elongatus on F. vesca increased about 20-fold over 4-6 months, X. index on fig (Ficus carica) increased more than 1,000 times over a comparable period. This low rate of multiplication of L. elongatus is the product of both a low rate of reproduction (about 1 egg/week) and a slow life cycle (about 19 weeks from female to female), as also found here. Although L. elongatus reproduced relatively slowly, reproduction was found to be continuous and females were still reproducing at the end of the experiments (16-23 weeks), so that the total reproduction appears comparable to that in other plant parasitic nematodes. This is because L. elongatus persists for a long time in the soil. © 1969 BRILL.