Resistance to Rhopalosiphum padi (Homoptera: Aphididae) in Triticale and Triticale-Derived Wheat Lines Resistant to Diuraphis noxia (Homoptera: Aphididae)

Rhopalosiphum padi (L.) (bird cherry-oat aphid) and Diuraphis noxia (Mordvilko) (Russian wheat aphid) are common aphid pests of wheat and can cooccur at relatively high levels within wheat fields. Resistance to both aphids has been identified in several triticale accessions. We conducted experiments to identify and characterize antibiosis-type resistance to R. padi in additional triticale lines and to test R. padi-resistance levels in several backcrossed, triticale-derived lines of D. noxia-resistant wheat. Triticale accessions ‘6A-558’, ‘H85-734’ and ‘M86-6174’ were identified with moderate levels of antibiosis to R. padi. All three accessions limited R. padi population growth relative to ‘Arapahoe’ over 13 d. 6A-558 increased development time of R. padi compared to that on Arapahoe, and 6A-558, H85-734 and M86-6174 each decreased the number of nymphs produced by R. padi over 7 d. Additional tests confirmed ‘N1185’ triticale as a strong source of resistance to R. padi, and showed that ‘Lamar’ wheat was not resistant to R. padi. Tests of wheat lines derived from crosses between N1185 and Lamar and then selected for resistance to D. noxia showed that three of 13 lines reduced the number of R. padiper plant, with resistance levels comparable to N1185 in two lines. Nymphiposition by R. padi measured over a 24-h period did not differ among any lines in no-choice tests. The results provide further support that triticale is a significant source of resistance to R. padi, but further work is needed to understand transference of R. padi-resistance from triticale to wheat.