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Doctoral thesis2024Open access

Insect-plant interactions within cultivar mixtures : volatile plant communication as an underlying mechanism

Kheam, Sokha


Promoting genotypic diversity of crops via cultivar mixtures presents a promising strategy to sustainably control insect pests and diseases, and thereby enhance yield. However, the underlying mechanisms responsible for reduced pest performance in cultivar mixtures remain unexplored. This thesis investigated the effects of volatile interactions between different cultivars in mixtures and their impact on insect pest performance. Two cultivars, initially growing at different rates, adjusted their growth to each other in the late stage due to aboveground chemical interactions. Volatile interactions between certain undamaged cultivars induced changes in volatile emissions of receiving plants, specifically the increased release of trans-β-ocimene and two unidentified compounds. The increases of trans-β-ocimene in receiving plants repelled aphids. Changes in receiving plants prolonged the non-nutrition uptake duration of aphid stylet penetration from epidermis to the phloem, but reduced the duration of active nutrition uptake in the phloem. It consequently decreased the aphid relative growth rate and intrinsic rate. A tropical field experiment showed that increasing soybean cultivar mixtures attract specific natural enemies at certain plant stages, while provide inconsistent effects on insect pests, with no changes in diseases or yield. The findings confirmed that volatile interactions between cultivars are context-specific, depending on the genetic identity of the emitter cultivar. This study sheds light on the significant role of volatiles in plant-plant interactions, affecting plant-insect interactions in cropping systems and increasing crop resilience against insect pests. This knowledge can help us develop integrated pest management by better understanding how complex mechanisms and processes in crop production systems can be and how we can influence them. It holds significant implications for both crop protection and the advancement of sustainable agricultural practices.


variety mixtures; integrated pest management; plant-plant interactions; insect-plant interactions; genetic plant diversity; barley; soybean; aphid; predator

Published in

Acta Universitatis Agriculturae Sueciae
2024, number: 2024:26ISBN: 978-91-8046-316-4, eISBN: 978-91-8046-317-1
Publisher: Swedish University of Agricultural Sciences

    UKÄ Subject classification

    Agricultural Science

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