2 . 3 Phenolic acid content in spring wheat ( Triticum aestivum ) grain

Bird cherry-oat aphid, (Rhopalosiphum padi /L./ (Hemi-ptera, Aphididae), is a holocyclic host-alternating species in temperate climates between wooden bird cherry, Prunus padus L. (Rosaceae) (winter, primary host) and grasses (summer, secondary hosts). In the spring, the aphid hatches from the winter eggs on P. padus and two wingless generations are developed before appearance of winged spring migrants. The migrants fly onto the summer hosts where they give rise of several parthenogenetic generations and finally comeback onto the primary host (P. padus) in October [1, 2]. The earlier study showed that volatile compounds emitted by P. padus play an important role in behaviour of the R. padi. The methyl salicylate hast recently received an interest due to its repellent effect on receptor cells of R. padi antena. On the other hand ben-zaldehyde was suggested as a possible plants stimulus of the R. padi [3, 4]. The present reports on emission P. padus volatile compounds during the bird cherry-oat aphid emigration on grasses during the spring and reemigration on the primary host during autumn. Methods: The bird cherry volatiles were trapped on 65 μm fiber (HS-SPME) and GC-MS analyses were performed on a Shimadzu GC 17A equipped with split/ splitless injector and interfaced to QP-5050 Shimadzu Mass Spectrometer. The carrier gas was helium, and the separation was done on a capillary column Equity-5 (30 m × 0.25 mm I.D. with 0.25 μm film thickness). The oven temperature was programmed as follows: 50°C (0.5 min), than from 50°C to 250°C (at 4°C/min), and from 250°C to 290°C (at 10°C/min), and final temperature was held for 4.5 min. The volatile compounds were identified on base of their mass spectra and retention times confirmed with standard samples. In addition, the spring and autumn migrations of the bird cherry-oat aphid were monitored in Aleksandria Park at Siedlce and feeding behaviour of the R. padi migrants on the primary host was studied using the EPG method [5]. Results and discussion: Obtained results showed that the bird cherry-oat aphid migrated from P. padus on grasses in the end of April and at beginning of May, instead the autumn recolonization of the primary host was started in the end of September. The spring migrants of the bird cherry-oat aphid were not feeding at all on the P. padus green shoots and leaves [6]. The performed analyses showed that the volatile methyl salicylate was especially strongly emitted by P. padus …