First published: 07 August 2025.
In an Agricultural and Forest Entomology article, “Method and timing of rhizobacteria inoculation to plant roots alters success and strength of aphid suppression”, the authors explore a biological alternative to pesticide resistance: boosting beneficial soil microbes that strengthen plant defences.
Their research focuses on reducing population growth of aphids, small sap-feeding insects that remove sugars and nutrients from plants and also transmit viruses that can cause significant yield losses.
Previous work showed that inoculating barley roots with Acidovorax radicis and Bacillus subtilis reduces aphid survival and reproduction. This led to new research on both the mechanisms behind these interactions and the most effective inoculation methods.
Having initially used seed or seedling soaking, group leader Zytynska explained, “we recognised this approach was unfeasible for our planned field trials and began exploring alternatives.”
As part of an MRes project, first author Blenkinsopp tested bacterial encapsulation in sodium alginate beads. She noted, “adding a single bacterial bead into soil or near plant roots is far simpler than soaking seeds and hoping for bacterial persistence until germination.”
Across three experiments, the authors compared inoculation methods, tested timing of inoculation (seed, seedling, grown plant), and examined effects under varying aphid densities.
The results support alginate beads as an effective delivery system for establishing root–bacteria associations, and they were found to remain viable when stored at 4 °C for up to 8 months. Inoculation at germination produced the strongest suppression of aphid population growth, consistent with bacteria interacting directly with emerging roots.
Aphid suppression was also more pronounced at higher initial aphid densities, suggesting that microbial inoculation may be particularly effective under greater pest pressure.
This study highlights alginate bead inoculation as a promising method for delivering beneficial microbes, offering a tractable approach for both experimental trials and sustainable pest management.
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