Abstract

Reproduction by X. diversicaudatum on strawberry (good host) and raspberry (poor host) and by L. elongatus on strawberry (good host) and turnip (poor host) were examined in a glasshouse pot trial at 18C. Populations of X. diversicaudatum increased 32-fold on the good host and those of L. elongatus 34-fold, while on the poor host populations of both nematodes increased 8-fold. The observed generation times for X. diversicaudatum were 23 weeks on strawberry and greater than 23 weeks on raspberry, and for L. elongatus were 17 weeks on strawberry and 21 weeks on turnip. The generation times were extrapolated into field conditions. There were more females with eggs, and more eggs per female on the good host than on the poor host. The total volume of nematode supported by a host plant only increased appreciably when L3, L4 or adults were present in the sample, and the good host supported 5 times the volume of X. diversicaudatum and 8 times the volume of L. elongatus than did the poor host. More galls were formed on the root system of the good host, by X. diversicaudatum and by L. elongatus, than on the poor host. The ratio of galls/nematode was such that on strawberry X. diversicaudatum induced more galls, a maximum of 0.31 galls/nematode, than L. elongatus, a maximum of 0.14 galls/nematode.