Effect of host plant on levels of reactive oxygen species and antioxidants in the cereal aphids Sitobion avenae and Rhopalosiphum padi

Effects of host plants on levels of reactive oxygen species (ROS) and antioxidant enzymes in tissues of Sitobion avenae (F.) and Rhopalosiphum padi (L.) were studied. Levels of superoxide anion (O2−) and hydrogen peroxide (H2O2) increased when aphids were transferred from winter wheat to two cultivars (Witon and Tornado) of winter triticale. ROS increase in triticale depended on the length of time that aphids fed on the triticale. The increase in O2− after transfer was greater on the less susceptible cultivar Witon than on the more susceptible cultivar Tornado. The increase in H2O2 after transfer was greater in the monophagous S. avenae than in the oligophagous R. padi. Activities of the ROS-scavenging enzymes superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) increased after aphids were transferred from winter wheat to winter triticale; only the increase in CAT was greater in R. padi than in S. avenae. APX activity in R. padi was greater on Witon than on Tornado. The content of the non-enzymatic antioxidant ascorbate (ASA) in aphids decreased when aphids were transferred from winter wheat to Witon, the less susceptible triticale cultivar, but remained unchanged when aphids were transferred to Tornado. The results of these experiments highlight the important role of oxidative stress in interactions between cereal aphids and their host plants.