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Dryad

Indirect effect of earthworms on wheat-aphid interactions

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Jan 18, 2024 version files 26.44 KB

Abstract

The aboveground and belowground compartments of terrestrial ecosystems, which are generally separated in interaction studies, are nevertheless linked by their dependence on the same plant. Soil organisms can influence interactions between plants and above-ground herbivores by changes in plant growth and chemistry.

In the present study, under controlled conditions the direct influence of earthworms and aphids on wheat traits (biomass; C and N content) was investigated. The effect of earthworms on aphid reproduction was also investigated, in order to demonstrate the indirect plant-trait-mediated effects.

The results showed a significant effect of both above and below-ground organisms on plant traits. Indeed, wheat biomass and carbon and nitrogen contents were influenced by the presence of earthworms and aphids, suggesting that earthworms can promote aboveground and belowground plant growth by promoting resource acquisition. Interestingly, the nitrogen content was significantly higher in the presence of aphids or earthworms alone and it was even higher when the two organisms were present together. Moreover, the results showed a strong effect of earthworms on aphids, with a reproduction rate almost twice as high as in the absence of earthworms.

These results could have implications for crop management, as they indicate that the presence of earthworms compensate the negative effect of aphids on plant biomass, probably by acting on nutrient uptake and plant defensive traits, despite a higher aphid reproduction rate in the presence of earthworms probably linked to nitrogen content. By addressing the effects of earthworms on both the pest performances and plant traits, this study highlights the need for further research on the indirect effects of below-ground compartments on pest performance. This study builds towards a better understanding of the interaction between soil, plant and herbivores and highlights the importance to study the pest management with a more holistic view of agroecosystems.