Differential responses of wheat cultivars to bird cherry-oat aphid and Russian wheat aphid infestations

Wheat (Triticum aestivum L.) production is frequently impacted by aphid feeding damage. The bird cherry-oat aphid (BCOA), Rhopalosiphum padi, and the russian wheat aphid (RWA), Diuraphis noxia, are key pests of wheat causing economic losses worldwide. Resistant cultivars have been developed to mitigate these losses; however, they are selected to limit damage from a target aphid species. In this work, we evaluated the interaction of BCOA and two RWA biotypes on the morphological responses of the resistant wheat cultivar ‘Dn7’ and the susceptible wheat cultivar ‘Custer’. We infested both cultivars with aphids and then conducted weekly morphological measurements for four weeks. One week after infestation, wheat plants under RWA1 had reduced aerial weight compared to controls. Differential responses between cultivars were observed in the root dry weight and total dry weight, where Dn7 showed no reduction. Two weeks after infestation, all tested parameters had a reduction when infested with aphids, regardless of wheat genotype or aphid species. Results were similar at week three excpt that Dn7 showed a differential tolerance when exposed to BCOA+RWA2, with the parameter of root dry weight. On the last evaluation date, plants had all the parameters reduced compared to the control, regardless of aphid species or cultivar. Thus, our study revealed that the differential responses between susceptible and resistant cultivars exposed to simultaneous infestation by two aphid species were most evident during the early period of infestation.