1Department of Biochemistry, Agricultural & Pedagogic University, Siedlce, Poland.
2Department of Entomology, Agricultural University, Wageningen, The Netherlands .
The bird cherry-oat aphid, Rhopalosiphum padi (L.) belongs to host alternating species, between bird cherry (primary host) and cereals (secondary host). Phenology of this phenomenon is quite well documented. However, there is no experimental data available on chemistry of the bird cherry xenobiotics during the aphid host-plant alternation. The present paper reports on changes in content of phenolics and cyanogenic glycosides in the bird cherry leaves before and during the R. padi migration to its secondary host.Results indicated that winged migrants of R. padi did not feed at all on the primary host. The highest level of the cyanogenic glycosides (prunasin) was found in the youngest bird cherry leaves. Development of the R. padi population was related to reduction of the prunasin concentration. Similar tendency was observed when intensity of cyanogenesis in the bird cherry leaves was studied. However, the opposite trends were observed for phenolic compounds. There was a significant increase in concentration of these xenobiotics in the bird cherry leaves before the aphid migration to secondary hosts. Possible role of the bird cherry xenobiotics in R. padi host-plant alternation is discussed.