Extrafloral (EF) nectaries recruit carnivorous arthropods that protect plants from herbivory, but they can also be exploited by nectar thieves. We studied the opportunistic, targeted predation (and destruction) of EF nectaries by insects, and the localized chemical defences that plants presumably use to minimize this effect. In field and laboratory experiments, we identified insects that were possibly responsible for EF nectary predation in Vicia faba (fava bean) and determined the extent and accuracy of the feeding damage done to the EF nectaries by these insects. We also performed biochemical analyses of plant tissue samples in order to detect microscale distribution patterns of chemical defences in the area of the EF nectary. We observed selective, targeted feeding on EF nectaries by several insect species, including some that are otherwise not primarily herbivorous. Biochemical analyses revealed high concentrations of L-3,4-dihydroxyphenylalanine, a non-protein amino acid that is toxic to insects, near and within the EF nectaries. These results suggest that plants allocate defences to the protection of EF nectaries from predation, consistent with expectations of optimal defence theory, and that this may not be entirely effective, as insects limit their exposure to these defences by consuming only the secreting tissue of the nectary.
|Proceedings of the Royal Society B: Biological Sciences
|Published - 7 Oct 2015
Bibliographical notePublisher Copyright:
© 2015 The Author(s) Published by the Royal Society. All rights reserved.
- Ecological costs
- Extrafloral nectaries
- Nectar robbery
- Optimal defence theory
- Plant–insect interactions
ASJC Scopus subject areas
- General Agricultural and Biological Sciences
- General Environmental Science
- General Biochemistry, Genetics and Molecular Biology
- General Immunology and Microbiology