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Exploring the Chemical Ecology of Gastropod-Insect-Plant Interactions

Gaylord Desurmont and co-workers recently reported that plants infested with slugs and plants co-infested with slugs and caterpillars were far less attractive to parasitoids than plants damaged by caterpillars only, and that volatile emissions, which provide foraging cues for parasitoids, were strongly reduced in co-infested plants (Journal of Chemical Ecology, 2016, 42: 183–192; see also figure). These findings of the InvaVOL project, which ended in 2015, inspired a new proposal, which was conceived jointly by Ted Turlings and Gaylord Desurmont who has left UniNE in the meantime to work for the European Biological Control Laboratory of USDA in Montpellier, France. The project was approved by the Swiss National Science Foundation and is expected to provide novel insight into the interactions between gastropods and plants, and the consequences of these interactions for insect herbivores and natural enemies. A postdoctoral fellow, Geoffrey Jaffuel, and a doctoral student, Diane Laplanche, will carry out the research.

The study of plant-herbivore interactions has been a cornerstone of modern ecology for decades, whereby the focus has mainly been on insect and mammalian herbivores. Little attention has so far been paid to another significant group of plant consumers: terrestrial mollusks belonging to the Gastropoda class, better known as snails and slugs. These have been found to elicit general defensive pathways in plants. The project intends to provide answers to the questions of how gastropod herbivory through elicitors in the mucus – a unique trait among herbivores - affects the secondary metabolism and volatile emissions in plants and how this in turn influences insect-plant interactions at the second and third trophic level.

Slugs also constitute important pests for a variety of cultivated crops and vegetables, and an important secondary aim of the project is therefore to explore new environmentally save strategies to control them, namely alginate beads containing mollusk-killing nematodes. Furthermore, it is envisioned to identify potent gastropod attractants to be incorporated in the beads as a lure.