Host Plant Resistance in Barley Genotypes Against Rhopalosiphum padi (Hemiptera: Aphididae): Antibiosis and Antixenosis

Abstract

Barley is an important cereal crop globally, and its productivity is significantly affected by aphid infestations, particularly Rhopalosiphum padi (bird cherry–oat aphid). The present study evaluates host plant resistance in different barley genotypes against R. padi, focusing on antibiosis and antixenosis mechanisms. A set of barley genotypes were screened under controlled laboratory and greenhouse conditions to assess aphid performance, feeding preference, and population development. Antixenosis was evaluated through free-choice assays, while antibiosis was determined by measuring aphid survival, development time, fecundity, and population growth parameters on different genotypes. Results indicated significant variation in resistance levels among barley genotypes. Certain genotypes exhibited strong antixenosis, as reflected by reduced aphid settling and feeding preference, suggesting the presence of deterrent plant traits. Other genotypes demonstrated antibiosis effects, resulting in prolonged nymphal development, reduced adult longevity, and decreased fecundity of R. padi. Combined resistance mechanisms were observed in a few genotypes, providing enhanced suppression of aphid population growth. Morphological and biochemical plant traits, including leaf surface characteristics and secondary metabolite profiles, were likely associated with resistance expression. Aphid population dynamics were strongly influenced by host genotype, with resistant lines supporting significantly lower population growth compared to susceptible controls. The study highlights the importance of integrating resistant barley genotypes into pest management strategies to reduce reliance on chemical insecticides. Overall, host plant resistance expressed through antibiosis and antixenosis provides an effective and sustainable approach for managing R. padi in barley agroecosystems, contributing to improved crop protection and yield stability.