EN
Probing behaviour of the grain aphid, Sitobion avenae (F.) on agarose-sucrose gels containing gramine at concentrations between 0.01 mM and 100 mM was examined using the EPG, electrical penetration graph technique. The following effects were recorded: the decrease in the number of probes, extension of the pathway phases, representing the penetration of leaf tissues by the aphid stylets and subsequent probing before reaching phloem and a strong reduction of the phases E1, E2 and G reflecting the activities of the stylets within the phloem and xylem elements as the consequence of increase in the gramine content in the gels. Accordingly, gramine appears to be the ‘anti-feedant’ compound towards the grain aphid. Its role as a probing stimulant for the aphid is discussed.