Analysis of chemosensory responses of second stage juveniles of Globodera rostochiensis using electrophysiological techniques

Eleclrophysiological techniques were developed to obtain recordings of elec trical activity from the anterior end of live, second stage juveniles (J2) of Globodera rostochiensis. Sequential exposure of individual J2 to test se miochemicals was also possible using a modified perfusion system. Concentra tion-dependent responses were obtained from J2 during exposure to 0.1, 1, 1 0 and 100 mM acetylcholine. The delay before any response was not concentra tion-dependent. The responses to 10 mM concentrations of several chemicals known to elicit a feeding response in insects were assessed. There was a si gnificant increase in spike activity When J2 were exposed to D-tryptophan b ut glycine and citric acid elicited no responses. Exposure to D-glutamic ac id resulted in a significant increase in spike activity but exposure to the L-isomer gave no response. This was confirmed by sequential exposure of J2 to the L- then to the D-isomer. Exposure to potato root diffusate elicited a response, whereas a non-host root diffusate from sugar beet and female s ecretory-excretory (S-E) product caused no change in activity.