5 research outputs found
A herbivore tag-and-trace system reveals contact- and density-dependent repellence of a root toxin
Foraging behavior of root feeding organisms strongly affects plant-environment-interactions and ecosystem processes. However, the impact of plant chemistry on root herbivore movement in the soil is poorly understood. Here, we apply a simple technique to trace the movement of soil-dwelling insects in their habitats without disturbing or restricting their interactions with host plants. We tagged the root feeding larvae of Melolontha melolontha with a copper ring and repeatedly located their position in relation to their preferred host plant, Taraxacum officinale, using a commercial metal detector. This method was validated and used to study the influence of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) on the foraging of M. melolontha. TA-G is stored in the latex of T. officinale and protects the roots from herbivory. Using behavioral arenas with TA-G deficient and control plants, we tested the impact of physical root access and plant distance on the effect of TA-G on M. melolontha. The larvae preferred TA-G deficient plants to control plants, but only when physical root contact was possible and the plants were separated by 5 cm. Melolontha melolontha showed no preference for TA-G deficient plants when the plants were grown 15 cm apart, which may indicate a trade-off between the cost of movement and the benefit of consuming less toxic food. We demonstrate that M. melolontha integrates host plant quality and distance into its foraging patterns and suggest that plant chemistry affects root herbivore behavior in a plant-density dependent manner. © 2017, Springer Science+Business Media New York
Novel Set-Up for Low-Disturbance Sampling of Volatile and Non-volatile Compounds from Plant Roots
Root-emitted volatile organic compounds: can they mediate belowground plant-plant interactions?
peer reviewedBackground
Aboveground, plants release volatile organic compounds (VOCs) that act as chemical
signals between neighbouring plants. It is now well documented that VOCs emitted by
the roots in the plant rhizosphere also play important ecological roles in the soil
ecosystem, notably in plant defence because they are involved in interactions between
plants, phytophagous pests and organisms of the third trophic level. The roles played
by root-emitted VOCs in between- and within-plant signalling, however, are still poorly
documented in the scientific literature.
Scope
Given that (1) plants release volatile cues mediating plant-plant interactions
aboveground, (2) roots can detect the chemical signals originating from their
neighbours, and (3) roots release VOCs involved in biotic interactions belowground,
the aim of this paper is to discuss the roles of VOCs in between- and within-plant
signalling belowground. We also highlight the technical challenges associated with the
analysis of root-emitted VOCs and the design of experiments targeting volatile-mediated
root-root interactions.
Conclusions
We conclude that root-root interactions mediated by volatile cues deserve more
research attention and that both the analytical tools and methods developed to study
the ecological roles played by VOCs in interplant signalling aboveground can be
adapted to focus on the roles played by root-emitted VOCs in between- and within-plant
signalling