Plant volatile emissions induced by insect and gastropod herbivory: a comparative study

Authors: MANN, LESLIE - University Of Neuchatel; LAPLANCHE, DIANE - University Of Neuchatel; DEGEN, THOMAS - University Of Neuchatel; TURLINGS, TED - University Of Neuchatel; DESURMONT, GAYLORD - European Biological Control Laboratory (EBCL)

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2021
Publication Date: 12/8/2021
Citation: Mann, L., Laplanche, D., Degen, T., Turlings, T.C., Desurmont, G.A. 2021. Plant volatile emissions induced by insect and gastropod herbivory: a comparative study. Scientific Reports. 11, 23698. https://doi.org/10.1038/s41598-021-02801-2.
DOI: https://doi.org/10.1038/s41598-021-02801-2

Interpretive Summary: Plants emit odors when they are attacked by herbivores. These smells are due to the production of specific molecules, which have been heavily studied in the case of insect herbivores. However, very little is known about what plants emit when they are attacked by slugs and snails. Here we studied the production of odors in 16 cultivated plant species attacked by the insect herbivore Spodoptera littoralis and the slug Arion vulgaris. Results showed that plants release higher amounts of volatile molecules and produce more specific blends of odors when they are attacked by insects compared to when they are attacked by slugs. This may be due to compounds present in insect and slug saliva that react differently with plants, or to the specificities of insect and slug damage: insect fed more on small young leaves, making multitudes of small holes in the leaves while slugs preferred to feed on old leaves, making larger holes in the leaves. This information will be of interest to scientists and those involved in crop protection.

Technical Abstract: Insect and gastropod herbivores are major plant consumers in terrestrial ecosystems and their importance as selective forces in the evolution of plant defensive traits is well accepted. However, their respective effects on plant responses have rarely been directly compared. Here we focused on the production of volatile organic compounds (VOCs) following herbivory. Numerous studies have shown that insect herbivory can lead to the production of specific VOCs attractive to natural enemies and/or involved in plant-plant communication, but the effects of gastropod herbivory on plant volatiles have been largely unexplored. We compared the effects of herbivory by the generalist insect herbivore Spodoptera littoralis and by generalist slugs from the genus Arion on VOCs production in 16 cultivated plant species. Results revealed that although slugs fed generally more than insects on the different species tested, plants produced higher amounts of volatiles and responded more specifically following insect damage compared to slug damage. Interestingly, 4 plant species produced a distinct blend of volatiles in response to insect damage but not to slug damage. These findings may result from differences in chemical elicitors associated with insect saliva and slug saliva and/or mucus, or from the physical specificities of insect and gastropod damage. Indeed S. littoralis typically fed on the youngest leaves of the plants and made many small holes in the leaves whereas Arion slugs typically fed on the older leaves and ate large chunks of leaf tissue. These findings are an important step toward a more inclusive view of plant responses to different types of herbivores and have implications in the debate on the ecological functions and evolution of plant volatiles.