Data from: Chemical ecology of fruit defense: synergistic and antagonistic interactions among amides from Piper

1. Although ripe, fleshy fruits function primarily to attract seed
dispersers, they must also be defended against diverse communities of seed
predators and pathogens. For some plants, the concentration and diversity
of secondary metabolites in fruits can exceed that of leaves and other
plant parts, but little is known about the functional significance of the
suites of compounds found in fruits. Fruit secondary metabolites may
function in defense, or they may play a variety of other roles in seed
development and dispersal. 2. In this study, we conducted a series of
experiments to test the effects of amides, a highly diverse class of
secondary metabolites found in Piper fruits, on a variety of antagonistic
fruit pests, including an insect seed predator (Sibaria englemani,
Pentatomidae) and three unidentified species of fungi isolated from ripe
Piper reticulatum (Piperaceae) fruits. We tested the effects of amide-rich
extracts from unripe and ripe fruits of Piper reticulatum and the effects
of two pure compounds, piperine and piplartine, presented alone and in
combination. 3. Amide-rich extracts from unripe and ripe fruits had no
effect on insect feeding preferences, but strong negative effects on
fungal growth rates. A comparison of the relative bioactivity of unripe
and ripe fruit extracts, controlling for concentration, showed that the
specific composition of compounds in unripe fruits provides a more
effective defense than that of ripe fruits against two of the three fungal
species tested. 4. Pure amides had variable effects on insect feeding
preferences and strong negative effects on fungal growth rates. Tests of
the bioactivity of two pure amides, presented alone and in combination,
showed that the same two compounds can interact either synergistically or
antagonistically in mixtures depending on the particular consumer
involved. 5. Together, these results suggest that the secondary
metabolites in fruits may be a key characteristic contributing to fruit
defense and plant reproductive success. Specifically, our results
emphasize: 1) the potential for slight changes in the composition of
mixtures to alter the efficacy of defense, and 2) the potential for
complex interactions among compounds in mixtures that can alter the
bioactivity of secondary metabolites differentially among different
consumers.