INVITRO STUDIES ON THE BEHAVIOR OF 2ND-STAGE JUVENILES OF HETERODERA-SCHACHTII (NEMATODA, HETERODERIDAE) IN RESPONSE TO HOST PLANT-ROOT EXUDATES

The behaviour of Heterodera schachtii second-stage juveniles in response to mustard (Sinapis alba) root exudates was observed and analysed under aseptic conditions in a standardized bioassay. Aggregation of juveniles on an agarose layer occurred within less than 30 min in the area where root exudates had been applied and persisted for several hours. Analysis of time-lapse video recordings showed that the aggregation did not result from a directed orientation of the juvenile towards the root exudate. This was supported by an orientation assay using single juveniles. Aggregated juveniles showed preinfection exploratory behaviour, including stylet thrusting and head-end bending, while staying at rest for several minutes.