Project

Discipline

plant-insect interaction; volatile organic compounds; Brassica rapa; Gastropoda; beneficial nematodes; invasive species; infochemical networks

Lead
Das Studium der Beziehungen zwischen Pflanzen und Pflanzenfressern nimmt einen wichtigen Platz in der Ökologie ein, wobei bislang vor allem pflanzenfressende Insekten im Zentrum des Interesses standen. Erstmalig erforschen wir in diesem Zusammenhang Landschnecken, eine andere sehr bedeutende Gruppe von Pflanzenfressern, und deren Einfluss auf die Wechselbeziehung zwischen Pflanzen, Insekten und deren natürlichen Feinden.
Lay summary
Landschnecken sind wichtige Schädlinge von Kulturpflanzen. Einige Arten wurden weltweit verschleppt und können in Ökosystemen, in denen sie sich neu ansiedeln, verheerende Auswirkungen haben. Aufgrund ihrer bedeutenden Stellung als Konsumenten kann man davon ausgehen, dass Schnecken eine grosse Rolle bei der Evolution der Pflanzenabwehr spielen. Von Gehäuse- und Nacktschnecken ist bekannt, dass sie in Pflanzen allgemeine Abwehrmechanismen auslösen können. Der von ihnen produzierte Schleim ist einmalig unter den Pflanzenfressern. Die Frage, wie dieser von den Pflanzen wahrgenommen wird und wie deren Stoffwechsel auf die darin enthaltenen Signalstoffe reagiert, wird erst seit kurzem untersucht. Unser Projekt verfolgt das Ziel, neue Einsichten in die grundlegende chemische Ökologie der Wechselbeziehungen zwischen Nacktschnecken und Pflanzen zu gewinnen, die in biologische Bekämpfungsmethoden einfliessen können. Dazu untersuchen wir folgende Fragen: Wie reagiert der pflanzliche Sekundärstoffwechsel auf Schneckenfrass, z.B. durch die Produktion von giftigen Stoffen? Veranlasst Schneckenfrass die Pflanzen, Duftstoffe freizusetzen, die natürliche Feinde der Schnecken anlocken? Von Interesse sind dabei insbesondere von den Wurzeln produzierte Lockstoffe für Fadenwürmer (Nematoden), die Schnecken abtöten. Wie beeinflusst die pflanzliche Abwehrreaktion, die durch Schneckenfrass ausgelöst wird, die Beziehungen zwischen Pflanzen und herbivoren Insekten sowie deren natürliche Feinde? Ein zweites, anwendungsorientiertes Ziel ist, neue umweltfreundliche Strategien zur Bekämpfung von Nachtschnecken zu entwickeln. Im Zentrum stehen Alginatkugeln, mit deren Hilfe die erwähnten Fadenwürmer ausgebracht werden können und die noch zu identifizierende Schneckenlockstoffe enthalten sollen.

Direct link to Lay Summary

Last update: 17.05.2016

Active participation

Number	Title	Start	Funding scheme

The study of plant-herbivore interactions has been a cornerstone of modern ecology for decades. The focus has been on insect and mammalian herbivores and little attention has so far been paid to another group of plant attackers of fundamental importance: terrestrial mollusks belonging to the Gastropoda class, also known as snails and slugs. Here we propose a project with which we hope to provide novel insight into the interactions between gastropods and plants, and the consequences of these interactions for insect herbivores and natural enemies. Terrestrial mollusks are major plant consumers and constitute important pests for a variety of cultivated crops and vegetables. Several species of terrestrial mollusks are highly invasive worldwide, and the extent of their effects of native environments can be devastating. Because of their importance as plant consumers, gastropod herbivores are thought to play an important role in the evolution of plant defenses. Snails and slugs have been found to elicit general defensive pathways in plants. In particular, the mucus produced by snails and slugs is unique among herbivores and have highly distinctive chemical compositions and physical proprieties. Questions about how mucus is perceived by plants during gastropod locomotion or herbivory, and how the primary and secondary plant metabolisms are affected by mucus elicitors, have only been addressed in recent years. The potential effects of gastropods on plant defenses may have consequences on plant interactions with other plant attackers and may also have consequences at the third trophic level; for example, the volatile compounds emitted by plants in response to gastropod herbivory may affect the foraging behavior of the natural enemies of insect herbivores in search of prey or hosts. The here proposed project will also investigate plants produce volatiles that are attractive to gastropod natural enemies, in particular root volatiles attractive to mollusk-killing nematodes. The mismatch between the site of gastropod-inflicted damage (aboveground) and the site of natural enemy attraction (belowground) makes this system a truly unique case in plant-herbivore interactions and can be of utmost importance for the general debate on the evolution and relevance of plant indirect defenses. Finally, gastropods are often opportunistic feeders and may even consume insects, as we have observed in preliminary experiments. An important secondary aim of the project is to explore new, environmentally save strategies to control slugs. Terrestrial mollusks are known to orient themselves toward potential sources of food using chemoreceptors located on the tips of their tentacles. With techniques that we have successfully used to study chemical attractants for insects and entomopathogenic nematodes, we envision to identify potent gastropod attractants. These will then be implemented in a new pest management technique currently under development: the use of beads to release beneficial nematodes in agricultural soils. For the proposed study, beads would be filled with mollusk-killing nematodes and imbibed with attractant compounds to lure the gastropods to the beads.In short, the project aims to reveal novel fundamental insight into plant-herbivore interactions, as well as to develop new pest management tools. This will be achieved by addressing the following questions:A- How does gastropod herbivory affect the secondary metabolism and volatile emissions in plants?B- How does gastropod herbivory affect insect-plant interactions at the second and third trophic level?C- Does gastropod herbivory induce plants to emit volatiles that attract natural enemies? D- What biochemical compounds are particularly attractive to gastropods?E- Can nematode-releasing beads be used as an effective management technique against gastropods?