Multi-trophic interactions are potentially important in
shaping community structure. Vertebrate florivory can eliminate entire
inflorescences and above-ground plant parts, which could affect the abundance
and diversity of insect populations. We examined the impact of florivory on the
performance of insect herbivores of the native Louisiana
iris, Iris hexagona.
This species reproduces sexually through seeds and clonally through rhizomes. A
previous study demonstrated that vertebrate florivory increased clonal growth, with
potentially positive effects on productivity and aboveground biomass. Leaves of
I. hexagona are
often attacked and destroyed by the leafminer Cerodontha iridiphora. We conducted a common garden
experiment to test if florivory indirectly affected leafminer fitness, which
would indicate a tri-trophic (florivore, plant,
leafminer) interaction. We assigned irises to one of four levels of florivory
(0, 1, 2, or 3 flowers removed), and recorded the subsequent density and mass
of leafminer pupae. Results indicate that the highest level of florivory significantly
decreased the number of leafminers. Florivory had no
effect on leafminer mass. Our results suggest that despite the negative effects
of florivory on iris sexual reproduction, it can benefit its overall fitness by
increasing clonal growth, and reducing the density of an important natural
enemy.