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TRAIT‐MEDIATED EFFECTS ON FLOWERS: ARTIFICIAL SPIDERS DECEIVE POLLINATORS AND DECREASE PLANT FITNESS
Author(s) -
Gonçalves-Souza Thiago,
Omena Paula M.,
Souza José César,
Romero Gustavo Q.
Publication year - 2008
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/07-1881.1
Subject(s) - biology , pollinator , predation , ecology , spider , foraging , trait , predator , pollination , pollen , computer science , programming language
Although predators can affect foraging behaviors of floral visitors, rarely is it known if these top‐down effects of predators may cascade to plant fitness through trait‐mediated interactions. In this study we manipulated artificial crab spiders on flowers of Rubus rosifolius to test the effects of predation risk on flower‐visiting insects and strength of trait‐mediated indirect effects to plant fitness. In addition, we tested which predator traits (e.g., forelimbs, abdomen) are recognized and avoided by pollinators. Total visitation rate was higher for control flowers than for flowers with an artificial crab spider. In addition, flowers with a sphere (simulating a spider abdomen) were more frequently visited than those with forelimbs or the entire spider model. Furthermore, the presence of artificial spiders decreased individual seed set by 42% and fruit biomass by 50%. Our findings indicate that pollinators, mostly bees, recognize and avoid flowers with predation risk; forelimbs seem to be the predator trait recognized and avoided by hymenopterans. Additionally, predator avoidance by pollinators resulted in pollen limitation, thereby affecting some components of plant fitness (fruit biomass and seed number). Because most pollinator species that recognized predation risk visited many other plant species, trait‐mediated indirect effects of spiders cascading down to plant fitness may be a common phenomenon in the Atlantic rainforest ecosystem.