Host plant species modulate whitefly‐mediated transmission of tomato leaf curl New Delhi virus and viral effects on vector performance

Background Tomato leaf curl New Delhi virus (ToLCNDV) is an emerging bipartite Begomovirus primarily transmitted by the whitefly Bemisia tabaci , causing severe yield losses in cucurbit and solanaceous crops. Despite its rapid spread, the differential susceptibility of these crop families and the vector–virus–host interactions driving transmission disparities remain poorly characterized. Results Our field surveys revealed widespread ToLCNDV infection, with high prevalence in cucurbits although infection in solanaceous crops was much less frequent. Subsequent vector transmission experiments demonstrated that B . tabaci efficiently acquired ToLCNDV from infected melon, tomato and tobacco plants, and that transmission efficiency and viral accumulation were significantly higher in melon plants. Whitefly host adaptability ranked melon > tomato > tobacco, aligning positively with transmission efficiency. Notably, ToLCNDV infection exerted a graded mutualistic effect on whitefly fitness across different plants: survival and reproduction were significantly enhanced on the non‐adaptive host tobacco, reproduction was promoted on the moderately adaptive host tomato, and no significant fitness effects were observed on the highly adaptive host melon. Conclusion These findings demonstrate that differential ToLCNDV transmission on cucurbits versus solanaceous crops is collectively shaped by vector host adaptability, host plant antiviral capacity, and virus‐mediated mutualism. Unraveling these mechanisms is crucial for accurately predicting viral epidemic risks and developing effective control strategies.