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Trait-mediated effects on flowers: artificial spiders deceive pollinators and decrease plant fitness
Thiago Gonçalves-Souza1, Paula M Omena, José César Souza
1Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia e Botânica, IBILCE, Universidade Estadual Paulista, Rua Cristóvão Colombo 2265, CEP 15054-000, São José do Rio Preto, SP, Brazil.
Ecology
|October 4, 2008
Summary
Predation risk from crab spiders on flowers reduces pollinator visits, leading to lower seed set and fruit biomass in Rubus rosifolius. Pollinators avoid flowers with spiders, causing trait-mediated indirect effects on plant fitness.
Area of Science:
- Ecology
- Behavioral Ecology
- Plant-Pollinator Interactions
Background:
- Predators significantly influence foraging behaviors of floral visitors.
- Top-down effects of predators on plant fitness via trait-mediated interactions are not well understood.
Purpose of the Study:
- To investigate the effects of predation risk on insect flower visitors.
- To quantify trait-mediated indirect effects of predators on plant fitness.
- To identify specific predator traits recognized and avoided by pollinators.
Main Methods:
- Artificial crab spiders were used to manipulate predation risk on Rubus rosifolius flowers.
- Flower visitation rates and components of plant fitness (seed set, fruit biomass) were measured.
- Pollinator avoidance of specific predator traits (forelimbs, abdomen) was assessed.
Main Results:
- Total visitation rate was higher for control flowers compared to those with artificial spiders.
- Flowers with only a spider abdomen (sphere) received more visits than those with forelimbs or the entire spider model.
- Artificial spiders decreased seed set by 42% and fruit biomass by 50%.
Conclusions:
- Pollinators, primarily bees, recognize and avoid flowers indicating predation risk.
- Forelimbs appear to be the key predator trait that hymenopterans avoid.
- Pollinator avoidance of predation risk leads to pollen limitation, negatively impacting plant fitness components.
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