Abstract
In cranberry (Vaccinium macrocarpon), phytoplasma infection increases plant susceptibility to herbivores; however, its role in shaping interactions between belowground and aboveground herbivores remains unclear. Here, we examined how phytoplasma infection and belowground herbivory by Japanese beetle (Popillia japonica) grubs jointly influence plant traits and performance of aboveground herbivores. Greenhouse experiments were conducted using a wild and a modern cranberry variety in a factorial design with infection status (uninfected vs. infected) and belowground herbivory (absence vs. presence). We measured nutrient (carbon and nitrogen) content, defence compounds (total phenolics and proanthocyanidins), and phytohormones (jasmonic acid [JA] and salicylic acid [SA]), along with performance of two foliar-feeding caterpillars, Sparganothis sulfureana and Lymantria dispar. Phytoplasma infection enhanced aboveground herbivore performance and was associated with higher nitrogen content, reduced phenolic compounds, lower JA levels, and elevated SA levels. In contrast, belowground herbivory induced plant defences, as evidenced by increased phenolics and JA, and reduced aboveground herbivore performance. Although the strength of these effects varied between varieties, the two factors produced opposing effects consistent with contrasting defence-related responses. Our findings show that phytoplasma infection and root herbivory exert contrasting influences on plant-mediated herbivore resistance, highlighting the importance of considering multiple stressors in plant-herbivore interactions within agroecosystems.
Subjects
- Ecology
- Plant sciences
Acknowledgements
We thank Robert Holdcraft, Yahel Ben-Zvi, and Vera Kyryczenko-Roth for their assistance with plant propagation, greenhouse experiments, and Japanese beetle collection. We are also grateful to Kristia Adams for her help with molecular studies, and Lindsay Lindhult for illustrating Fig. 6. This research was supported by the New Jersey Blueberry/Cranberry Research Council, the Yunnan International Joint Laboratory of Fruit-Vegetable-Flower Invasive Insect Pest Management (Yunnan FVF-IPM International Joint Lab; No. 202303AP140018), the College of Agricultural Sciences at Penn State, USDA ARS Agreement No. 58-8042-3-049, and USDA’s National Institute of Food and Agriculture and Hatch Appropriations under Projects #PEN04600, #PEN04606 and Accession #1009362.
Funding
This research was supported by the New Jersey Blueberry/Cranberry Research Council, the Yunnan International Joint Laboratory of Fruit-Vegetable-Flower Invasive Insect Pest Management (Yunnan FVF-IPM International Joint Lab; No. 202303AP140018), the College of Agricultural Sciences at Penn State, USDA ARS Agreement No. 58-8042-3-049, and USDA’s National Institute of Food and Agriculture and Hatch Appropriations under Projects #PEN04600, #PEN04606 and Accession #1009362.
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Liu, Ht., Han, P., Tooker, J.F. et al. From the ground up: Belowground herbivory and phytoplasma infection influence aboveground herbivore performance.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-64596-4
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DOI: https://doi.org/10.1038/s41598-026-64596-4
Keywords
- Defence induction hypothesis
- Plant-herbivore interactions
- Cranberry false blossom disease
- C/N
- Phenolics
- Phytohormones
Source: Ecology - nature.com
