Arbuscular mycorrhizal fungus Acaulospora delicata modulates tri-trophic interactions between wheat cultivars and Sitobion avenae under drought stress

Aphid-microbe-plant interactions are fundamental to understanding plant responses to biotic and abiotic stressors. Aphid is a significant pest distressing wheat crops globally, especially under drought conditions. The interactions between the aphid Sitobion avenae and arbuscular mycorrhizal fungus (AMF) Acaulospora delicata , particularly in wheat cultivars under drought conditions, reveal significant dynamics affecting pest performance and plant health. However, the influence of AMF on aphid performance across different wheat-cultivars under water-deficit stress, remains poorly understood. We investigated the effects of AMF on the performance of S. avenae on two wheat cultivars, Yunhao-618 (drought-resistant) and Xinong-1376 (drought-non-resistant), under varying water conditions. Our results revealed that A. delicata significantly increased root length colonization in Xinong-1376 (67%) and improves aphid developmental duration, longevity, and fecundity under both well-watered and water-deficit conditions. Notably, aphid nymphs exhibited prolonged DDs without AMF-associations, particularly on Xinong-1376 under drought-stress. In contrast, associations with AMF promoted faster growth rates and higher fecundity in Yunhao-618, suggesting that AMF-association can improve water stress effects. Honeydew production was higher in AMF-associated plants under well-watered conditions. Aphid fresh and dry body masses, and water balance traits tended higher on drought-resistant cultivars Yunhao-618 with AMF association under well-water conditions. Additionally, aphids displayed a preference for AMF-associated drought non-resistant Xinong-1376 plants, indicating a strong influence of AMF on host choice dynamics. Our findings reveal that A. delicata modulates plant-aphid dynamics by enhancing plant drought resilience while inadvertently promoting aphid fitness. This underscores the complex role of AMF intri-trophic interactions and their broader implications under climate change scenarios.