Data from: Complex multitrophic species interactions and fitness costs: Intricate consequences of jasmonate and salicylate induced plant defenses

Induced plant defenses regulated by jasmonic acid (JA) and salicylic acid
(SA) initiate a cascade of effects, from defense expression to changes in
arthropod community structure and species interactions, that can
ultimately influence plant fitness. Yet the long-term consequences of
these processes remain poorly understood, particularly in perennial
tropical systems. We investigated how activation of JA and SA signaling
pathways shapes arthropod community composition and plant reproductive
success in Trichogoniopsis adenantha (Asteraceae), a glandular
trichome-bearing shrub native to the Brazilian Atlantic rainforest. Using
chemical elicitors, we induced JA and SA defenses for up to 16 months and
monitored herbivore and predator assemblages, herbivory patterns, trichome
expression, pyrrolizidine alkaloid concentrations, and plant short-term
fecundity. JA-elicited plants exhibited higher pyrrolizidine alkaloid
levels in flowers, reduced leaf herbivory, and lower seed damage by
pre-dispersal seed predators. However, these plants experienced increased
colonization by sap-feeding insects. In contrast, SA-elicited plants were
more vulnerable to chewing herbivores but more resistant to sap-feeders.
Despite similar reductions in seed predation across both treatments, JA
and SA induction significantly reduced ovary fertilization, likely due to
changes in floral traits and decreased pollinator visitation, ultimately
imposing substantial fitness costs. Additionally, seasonal turnover in
arthropod communities was accompanied by temporal variation in how
defenses structured species composition and abundance. Our findings
demonstrate that phytohormone-mediated defenses can simultaneously induce
resistance and susceptibility across herbivore guilds, with divergent
impacts on predator associations. Although defense induction reduced
herbivore damage, it compromised short-term fecundity, revealing
trade-offs between defense and reproduction. By linking induced defenses
to multi-trophic interactions over time, this study highlights the
ecological complexity of plant defense strategies in biodiverse tropical
ecosystems.