Datensatz

Zusammenfassung

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 soildwelling
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 TAG
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.