Shiraz University Iran Agricultural Research 1013-9885 45 2 2026 07 01 Interactive effects of irrigation and nitrogen regimes on Rhopalosiphum padi demography in drought-tolerant and drought-sensitive barley cultivars 36 51 8800 10.22099/iar.2026.55727.1742 EN Maryam Aleosfoor Department of Plant Protection, School of Agriculture, Shiraz University, Shiraz, I. R. Iran 0000-0001-9372-2122 Khatereh Zohrabi Dehdezi Department of Plant Protection, School of Agriculture, Shiraz University, Shiraz, I. R. Iran Lida Fekrat Department of Plant Protection, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, I. R. Iran 0000-0002-5189-9488 Aurang Kavousi Department of Plant Protection, Faculty of Agriculture, University of Zanjan, Zanjan, I. R. Iran Journal Article 2026 02 21 Sustainable control of cereal aphids under climate change requires a mechanistic understanding of how water and nutrient management interact with host drought tolerance to shape pest demography. The oat leaf aphid, <em>Rhopalosiphum padi</em> L., is a persistent constraint in cereal systems, yet its responses to combined abiotic and nutritional stress remain unclear. We evaluated irrigation and nitrogen effects on aphid life history across two barley cultivars differing in drought sensitivity. Plants were grown under three soil moisture levels (100%, 75%, and 50% field capacity) and three nitrogen rates (0, 75, and 150 mg N kg⁻¹ soil), and aphid demographic parameters were quantified using the age–stage, two-sex life table. The design quantified non-linear interactions among host drought tolerance, water availability, and nitrogen supply. The drought-tolerant cultivar 'Sararood' constrained aphid development and reproduction, particularly under water deficit, resulting in prolonged development and reduced intrinsic rates of increase (<em>r</em>), from 0.2272 d⁻¹ on 'Afzal' under optimal irrigation to 0.0090 d⁻¹ on 'Sararood' under severe water stress. In contrast, aphids on the drought-sensitive cultivar 'Afzal' showed rapid population growth under full irrigation but showed collapse under drought. Nitrogen effects were context-dependent and interacted with both moisture regime and cultivar physiology; while nitrogen fertilization had negligible effects on developmental duration, it reduced the intrinsic rate of increase under severe drought in 'Afzal'. Notably, moderate irrigation combined with moderate nitrogen on 'Sararood' minimized aphid population growth, a resource-efficient regime. These results highlight co-optimization of cultivar choice with precision irrigation and fertilization as a climate-smart integrated pest management (IPM) strategy. https://iar.shirazu.ac.ir/article_8800_d1d72a418753ac9c1fd002c723a68bc6.pdf