Department of Biochemistry, Agricultural and Pedagogic University, Siedlce, Poland.
Herbivores are sensitive to highly toxic free oxygen radicals e.g. singlet oxygen (1O2), ground state molecular oxygen (3O2), superoxide (O-2), hydrogen peroxide (H2O2) as well as hydroperoxy and hydroxyl radicals. Many of these radicals are generated from prooxidants naturally occurring within plant tissues. Among them phenolics, flavonoids and furanocoumarins strongly influence cereal aphids' biology. However, the aphids can perform on cultivars even rich in the prooxidants since they developed antioxidative enzymes. The present paper reports on activity of superoxide dismutase and catalase involved in detoxication of the free oxygen radicals by the bird cherry-oat aphid Rhopalosiphum padi (L.). Among studied aphid morphs, the highest activity showed winged migrants that colonise new hosts. Before migration of the bird cherry-oat aphid from winter host (bird cherry; Prunus padus L.) to summer hosts (cereals), an increase in activity of the superoxide dismutase and catalase was observed. When migrants started to feed on cereals increase in activity of the aphid enzymes was noted. The role of the superoxide dismutase and catalase in the bird cherry-oat aphid's adaptation to free oxygen radicals and cereal prooxidants is discussed.