Agricultural landscape simplification affects wild plant fitness indirectly through herbivore-mediated changes in floral display

As natural landscapes are modified and converted into simplified
agricultural landscapes, the community composition and interactions of
organisms persisting in these modified landscapes are altered. While many
studies examine the consequences of these changing interactions for crops,
few have evaluated the effects on wild plants. Here, we examine how
pollinator and herbivore interactions affect fitness for wild resident and
phytometer plants at sites along a landscape gradient ranging from natural
to highly simplified. We tested the direct and indirect effects of
landscape composition on plant traits and fitness mediated by insect
interactions. For phytometer plants exposed to herbivores, we found that
greater landscape complexity corresponded with elevated herbivore damage,
which reduced total flower production but increased individual flower
size. Though larger flowers increased pollination, the reduction in
flowers ultimately reduced plant fitness. Herbivory was also higher in
complex landscapes for resident plants, but overall damage was low and
therefore did not have a cascading effect on floral display and fitness.
This work highlights that landscape composition directly affects patterns
of herbivory with cascading effects on pollination and wild plant fitness.
Further, the absence of fitness consequences for resident plants suggests
that they may be adapted to their local insect community.