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A meta-analysis of predation risk effects on pollinator behaviour.

Romero GQ, Antiqueira PA, Koricheva J - PLoS ONE (2011)

Bottom Line: The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36%) and time spent on flowers (by 51%) by pollinators.The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters) nor on pollinator lifestyle (social vs. solitary).However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil. gq_romero@yahoo.com.br

ABSTRACT
Flower-visiting animals are constantly under predation risk when foraging and hence might be expected to evolve behavioural adaptations to avoid predators. We reviewed the available published and unpublished data to assess the overall effects of predators on pollinator behaviour and to examine sources of variation in these effects. The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36%) and time spent on flowers (by 51%) by pollinators. The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters) nor on pollinator lifestyle (social vs. solitary). However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera. Furthermore, larger pollinators showed weaker responses to predation risk, probably because they are more difficult to capture. Presence of live crab spiders on flowers had weaker effects on pollinator behaviour than presence of dead or artificial crab spiders or other objects (e.g. dead bees, spheres), suggesting that predator crypsis may be effective to some extent. These results add to a growing consensus on the importance of considering both predator and pollinator characteristics from a community perspective.

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Effects (mean ln R and 95% CI) of live and artificial crab spiders on pollinators of different body size.Sample sizes are indicated next to the error bars. Negative effects indicate decrease in visitation rate on flowers with predators present; effects are considered significant if 95% CI does not include 0.
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pone-0020689-g004: Effects (mean ln R and 95% CI) of live and artificial crab spiders on pollinators of different body size.Sample sizes are indicated next to the error bars. Negative effects indicate decrease in visitation rate on flowers with predators present; effects are considered significant if 95% CI does not include 0.

Mentions: We have also examined the effect of pollinator size in studies using live and artificial crab spiders. Small and medium size arthropods decreased visitation rate by 21% and 13%, respectively, in the presence of live crab spiders, whereas large arthropods (e.g., Bombus, Xylocopa) showed no changes in flower visitation rate, i.e., confidence intervals for large pollinators do not overlap those for other prey size categories (Fig. 4). The difference among pollinator size categories was marginally significant for live predators (Qb = 0.64, P = 0.075, df = 2), but not for artificial spider models (Fig. 4, Qb = 5.24, P = 0.124, df = 2).


A meta-analysis of predation risk effects on pollinator behaviour.

Romero GQ, Antiqueira PA, Koricheva J - PLoS ONE (2011)

Effects (mean ln R and 95% CI) of live and artificial crab spiders on pollinators of different body size.Sample sizes are indicated next to the error bars. Negative effects indicate decrease in visitation rate on flowers with predators present; effects are considered significant if 95% CI does not include 0.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3113803&req=5

pone-0020689-g004: Effects (mean ln R and 95% CI) of live and artificial crab spiders on pollinators of different body size.Sample sizes are indicated next to the error bars. Negative effects indicate decrease in visitation rate on flowers with predators present; effects are considered significant if 95% CI does not include 0.
Mentions: We have also examined the effect of pollinator size in studies using live and artificial crab spiders. Small and medium size arthropods decreased visitation rate by 21% and 13%, respectively, in the presence of live crab spiders, whereas large arthropods (e.g., Bombus, Xylocopa) showed no changes in flower visitation rate, i.e., confidence intervals for large pollinators do not overlap those for other prey size categories (Fig. 4). The difference among pollinator size categories was marginally significant for live predators (Qb = 0.64, P = 0.075, df = 2), but not for artificial spider models (Fig. 4, Qb = 5.24, P = 0.124, df = 2).

Bottom Line: The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36%) and time spent on flowers (by 51%) by pollinators.The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters) nor on pollinator lifestyle (social vs. solitary).However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil. gq_romero@yahoo.com.br

ABSTRACT
Flower-visiting animals are constantly under predation risk when foraging and hence might be expected to evolve behavioural adaptations to avoid predators. We reviewed the available published and unpublished data to assess the overall effects of predators on pollinator behaviour and to examine sources of variation in these effects. The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36%) and time spent on flowers (by 51%) by pollinators. The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters) nor on pollinator lifestyle (social vs. solitary). However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera. Furthermore, larger pollinators showed weaker responses to predation risk, probably because they are more difficult to capture. Presence of live crab spiders on flowers had weaker effects on pollinator behaviour than presence of dead or artificial crab spiders or other objects (e.g. dead bees, spheres), suggesting that predator crypsis may be effective to some extent. These results add to a growing consensus on the importance of considering both predator and pollinator characteristics from a community perspective.

Show MeSH
Related in: MedlinePlus